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initial comit, ported scout_sdk and added hunter support

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## Using GoogleTest from various build systems ##
GoogleTest comes with pkg-config files that can be used to determine all
necessary flags for compiling and linking to GoogleTest (and GoogleMock).
Pkg-config is a standardised plain-text format containing
* the includedir (-I) path
* necessary macro (-D) definitions
* further required flags (-pthread)
* the library (-L) path
* the library (-l) to link to
All current build systems support pkg-config in one way or another. For
all examples here we assume you want to compile the sample
`samples/sample3_unittest.cc`.
### CMake ###
Using `pkg-config` in CMake is fairly easy:
```
cmake_minimum_required(VERSION 3.0)
cmake_policy(SET CMP0048 NEW)
project(my_gtest_pkgconfig VERSION 0.0.1 LANGUAGES CXX)
find_package(PkgConfig)
pkg_search_module(GTEST REQUIRED gtest_main)
add_executable(testapp samples/sample3_unittest.cc)
target_link_libraries(testapp ${GTEST_LDFLAGS})
target_compile_options(testapp PUBLIC ${GTEST_CFLAGS})
include(CTest)
add_test(first_and_only_test testapp)
```
It is generally recommended that you use `target_compile_options` + `_CFLAGS`
over `target_include_directories` + `_INCLUDE_DIRS` as the former includes not
just -I flags (GoogleTest might require a macro indicating to internal headers
that all libraries have been compiled with threading enabled. In addition,
GoogleTest might also require `-pthread` in the compiling step, and as such
splitting the pkg-config `Cflags` variable into include dirs and macros for
`target_compile_definitions()` might still miss this). The same recommendation
goes for using `_LDFLAGS` over the more commonplace `_LIBRARIES`, which
happens to discard `-L` flags and `-pthread`.
### Autotools ###
Finding GoogleTest in Autoconf and using it from Automake is also fairly easy:
In your `configure.ac`:
```
AC_PREREQ([2.69])
AC_INIT([my_gtest_pkgconfig], [0.0.1])
AC_CONFIG_SRCDIR([samples/sample3_unittest.cc])
AC_PROG_CXX
PKG_CHECK_MODULES([GTEST], [gtest_main])
AM_INIT_AUTOMAKE([foreign subdir-objects])
AC_CONFIG_FILES([Makefile])
AC_OUTPUT
```
and in your `Makefile.am`:
```
check_PROGRAMS = testapp
TESTS = $(check_PROGRAMS)
testapp_SOURCES = samples/sample3_unittest.cc
testapp_CXXFLAGS = $(GTEST_CFLAGS)
testapp_LDADD = $(GTEST_LIBS)
```
### Meson ###
Meson natively uses pkgconfig to query dependencies:
```
project('my_gtest_pkgconfig', 'cpp', version : '0.0.1')
gtest_dep = dependency('gtest_main')
testapp = executable(
'testapp',
files(['samples/sample3_unittest.cc']),
dependencies : gtest_dep,
install : false)
test('first_and_only_test', testapp)
```
### Plain Makefiles ###
Since `pkg-config` is a small Unix command-line utility, it can be used
in handwritten `Makefile`s too:
```
GTEST_CFLAGS = `pkg-config --cflags gtest_main`
GTEST_LIBS = `pkg-config --libs gtest_main`
.PHONY: tests all
tests: all
./testapp
all: testapp
testapp: testapp.o
$(CXX) $(CXXFLAGS) $(LDFLAGS) $< -o $@ $(GTEST_LIBS)
testapp.o: samples/sample3_unittest.cc
$(CXX) $(CPPFLAGS) $(CXXFLAGS) $< -c -o $@ $(GTEST_CFLAGS)
```
### Help! pkg-config can't find GoogleTest! ###
Let's say you have a `CMakeLists.txt` along the lines of the one in this
tutorial and you try to run `cmake`. It is very possible that you get a
failure along the lines of:
```
-- Checking for one of the modules 'gtest_main'
CMake Error at /usr/share/cmake/Modules/FindPkgConfig.cmake:640 (message):
None of the required 'gtest_main' found
```
These failures are common if you installed GoogleTest yourself and have not
sourced it from a distro or other package manager. If so, you need to tell
pkg-config where it can find the `.pc` files containing the information.
Say you installed GoogleTest to `/usr/local`, then it might be that the
`.pc` files are installed under `/usr/local/lib64/pkgconfig`. If you set
```
export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig
```
pkg-config will also try to look in `PKG_CONFIG_PATH` to find `gtest_main.pc`.

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<b>P</b>ump is <b>U</b>seful for <b>M</b>eta <b>P</b>rogramming.
# The Problem #
Template and macro libraries often need to define many classes,
functions, or macros that vary only (or almost only) in the number of
arguments they take. It's a lot of repetitive, mechanical, and
error-prone work.
Variadic templates and variadic macros can alleviate the problem.
However, while both are being considered by the C++ committee, neither
is in the standard yet or widely supported by compilers. Thus they
are often not a good choice, especially when your code needs to be
portable. And their capabilities are still limited.
As a result, authors of such libraries often have to write scripts to
generate their implementation. However, our experience is that it's
tedious to write such scripts, which tend to reflect the structure of
the generated code poorly and are often hard to read and edit. For
example, a small change needed in the generated code may require some
non-intuitive, non-trivial changes in the script. This is especially
painful when experimenting with the code.
# Our Solution #
Pump (for Pump is Useful for Meta Programming, Pretty Useful for Meta
Programming, or Practical Utility for Meta Programming, whichever you
prefer) is a simple meta-programming tool for C++. The idea is that a
programmer writes a `foo.pump` file which contains C++ code plus meta
code that manipulates the C++ code. The meta code can handle
iterations over a range, nested iterations, local meta variable
definitions, simple arithmetic, and conditional expressions. You can
view it as a small Domain-Specific Language. The meta language is
designed to be non-intrusive (s.t. it won't confuse Emacs' C++ mode,
for example) and concise, making Pump code intuitive and easy to
maintain.
## Highlights ##
* The implementation is in a single Python script and thus ultra portable: no build or installation is needed and it works cross platforms.
* Pump tries to be smart with respect to [Google's style guide](https://github.com/google/styleguide): it breaks long lines (easy to have when they are generated) at acceptable places to fit within 80 columns and indent the continuation lines correctly.
* The format is human-readable and more concise than XML.
* The format works relatively well with Emacs' C++ mode.
## Examples ##
The following Pump code (where meta keywords start with `$`, `[[` and `]]` are meta brackets, and `$$` starts a meta comment that ends with the line):
```
$var n = 3 $$ Defines a meta variable n.
$range i 0..n $$ Declares the range of meta iterator i (inclusive).
$for i [[
$$ Meta loop.
// Foo$i does blah for $i-ary predicates.
$range j 1..i
template <size_t N $for j [[, typename A$j]]>
class Foo$i {
$if i == 0 [[
blah a;
]] $elif i <= 2 [[
blah b;
]] $else [[
blah c;
]]
};
]]
```
will be translated by the Pump compiler to:
```
// Foo0 does blah for 0-ary predicates.
template <size_t N>
class Foo0 {
blah a;
};
// Foo1 does blah for 1-ary predicates.
template <size_t N, typename A1>
class Foo1 {
blah b;
};
// Foo2 does blah for 2-ary predicates.
template <size_t N, typename A1, typename A2>
class Foo2 {
blah b;
};
// Foo3 does blah for 3-ary predicates.
template <size_t N, typename A1, typename A2, typename A3>
class Foo3 {
blah c;
};
```
In another example,
```
$range i 1..n
Func($for i + [[a$i]]);
$$ The text between i and [[ is the separator between iterations.
```
will generate one of the following lines (without the comments), depending on the value of `n`:
```
Func(); // If n is 0.
Func(a1); // If n is 1.
Func(a1 + a2); // If n is 2.
Func(a1 + a2 + a3); // If n is 3.
// And so on...
```
## Constructs ##
We support the following meta programming constructs:
| `$var id = exp` | Defines a named constant value. `$id` is valid util the end of the current meta lexical block. |
|:----------------|:-----------------------------------------------------------------------------------------------|
| `$range id exp..exp` | Sets the range of an iteration variable, which can be reused in multiple loops later. |
| `$for id sep [[ code ]]` | Iteration. The range of `id` must have been defined earlier. `$id` is valid in `code`. |
| `$($)` | Generates a single `$` character. |
| `$id` | Value of the named constant or iteration variable. |
| `$(exp)` | Value of the expression. |
| `$if exp [[ code ]] else_branch` | Conditional. |
| `[[ code ]]` | Meta lexical block. |
| `cpp_code` | Raw C++ code. |
| `$$ comment` | Meta comment. |
**Note:** To give the user some freedom in formatting the Pump source
code, Pump ignores a new-line character if it's right after `$for foo`
or next to `[[` or `]]`. Without this rule you'll often be forced to write
very long lines to get the desired output. Therefore sometimes you may
need to insert an extra new-line in such places for a new-line to show
up in your output.
## Grammar ##
```
code ::= atomic_code*
atomic_code ::= $var id = exp
| $var id = [[ code ]]
| $range id exp..exp
| $for id sep [[ code ]]
| $($)
| $id
| $(exp)
| $if exp [[ code ]] else_branch
| [[ code ]]
| cpp_code
sep ::= cpp_code | empty_string
else_branch ::= $else [[ code ]]
| $elif exp [[ code ]] else_branch
| empty_string
exp ::= simple_expression_in_Python_syntax
```
## Code ##
You can find the source code of Pump in [scripts/pump.py](../scripts/pump.py). It is still
very unpolished and lacks automated tests, although it has been
successfully used many times. If you find a chance to use it in your
project, please let us know what you think! We also welcome help on
improving Pump.
## Real Examples ##
You can find real-world applications of Pump in [Google Test](https://github.com/google/googletest/tree/master/googletest) and [Google Mock](https://github.com/google/googletest/tree/master/googlemock). The source file `foo.h.pump` generates `foo.h`.
## Tips ##
* If a meta variable is followed by a letter or digit, you can separate them using `[[]]`, which inserts an empty string. For example `Foo$j[[]]Helper` generate `Foo1Helper` when `j` is 1.
* To avoid extra-long Pump source lines, you can break a line anywhere you want by inserting `[[]]` followed by a new line. Since any new-line character next to `[[` or `]]` is ignored, the generated code won't contain this new line.

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This guide will explain how to use the Google Testing Framework in your Xcode projects on Mac OS X. This tutorial begins by quickly explaining what to do for experienced users. After the quick start, the guide goes provides additional explanation about each step.
# Quick Start #
Here is the quick guide for using Google Test in your Xcode project.
1. Download the source from the [website](https://github.com/google/googletest) using this command: `svn checkout http://googletest.googlecode.com/svn/trunk/ googletest-read-only`.
1. Open up the `gtest.xcodeproj` in the `googletest-read-only/xcode/` directory and build the gtest.framework.
1. Create a new "Shell Tool" target in your Xcode project called something like "UnitTests".
1. Add the gtest.framework to your project and add it to the "Link Binary with Libraries" build phase of "UnitTests".
1. Add your unit test source code to the "Compile Sources" build phase of "UnitTests".
1. Edit the "UnitTests" executable and add an environment variable named "DYLD\_FRAMEWORK\_PATH" with a value equal to the path to the framework containing the gtest.framework relative to the compiled executable.
1. Build and Go.
The following sections further explain each of the steps listed above in depth, describing in more detail how to complete it including some variations.
# Get the Source #
Currently, the gtest.framework discussed here isn't available in a tagged release of Google Test, it is only available in the trunk. As explained at the Google Test [site](https://github.com/google/googletest), you can get the code from anonymous SVN with this command:
```
svn checkout http://googletest.googlecode.com/svn/trunk/ googletest-read-only
```
Alternatively, if you are working with Subversion in your own code base, you can add Google Test as an external dependency to your own Subversion repository. By following this approach, everyone that checks out your svn repository will also receive a copy of Google Test (a specific version, if you wish) without having to check it out explicitly. This makes the set up of your project simpler and reduces the copied code in the repository.
To use `svn:externals`, decide where you would like to have the external source reside. You might choose to put the external source inside the trunk, because you want it to be part of the branch when you make a release. However, keeping it outside the trunk in a version-tagged directory called something like `third-party/googletest/1.0.1`, is another option. Once the location is established, use `svn propedit svn:externals _directory_` to set the svn:externals property on a directory in your repository. This directory won't contain the code, but be its versioned parent directory.
The command `svn propedit` will bring up your Subversion editor, making editing the long, (potentially multi-line) property simpler. This same method can be used to check out a tagged branch, by using the appropriate URL (e.g. `https://github.com/google/googletest/releases/tag/release-1.0.1`). Additionally, the svn:externals property allows the specification of a particular revision of the trunk with the `-r_##_` option (e.g. `externals/src/googletest -r60 http://googletest.googlecode.com/svn/trunk`).
Here is an example of using the svn:externals properties on a trunk (read via `svn propget`) of a project. This value checks out a copy of Google Test into the `trunk/externals/src/googletest/` directory.
```
[Computer:svn] user$ svn propget svn:externals trunk
externals/src/googletest http://googletest.googlecode.com/svn/trunk
```
# Add the Framework to Your Project #
The next step is to build and add the gtest.framework to your own project. This guide describes two common ways below.
* **Option 1** --- The simplest way to add Google Test to your own project, is to open gtest.xcodeproj (found in the xcode/ directory of the Google Test trunk) and build the framework manually. Then, add the built framework into your project using the "Add->Existing Framework..." from the context menu or "Project->Add..." from the main menu. The gtest.framework is relocatable and contains the headers and object code that you'll need to make tests. This method requires rebuilding every time you upgrade Google Test in your project.
* **Option 2** --- If you are going to be living off the trunk of Google Test, incorporating its latest features into your unit tests (or are a Google Test developer yourself). You'll want to rebuild the framework every time the source updates. to do this, you'll need to add the gtest.xcodeproj file, not the framework itself, to your own Xcode project. Then, from the build products that are revealed by the project's disclosure triangle, you can find the gtest.framework, which can be added to your targets (discussed below).
# Make a Test Target #
To start writing tests, make a new "Shell Tool" target. This target template is available under BSD, Cocoa, or Carbon. Add your unit test source code to the "Compile Sources" build phase of the target.
Next, you'll want to add gtest.framework in two different ways, depending upon which option you chose above.
* **Option 1** --- During compilation, Xcode will need to know that you are linking against the gtest.framework. Add the gtest.framework to the "Link Binary with Libraries" build phase of your test target. This will include the Google Test headers in your header search path, and will tell the linker where to find the library.
* **Option 2** --- If your working out of the trunk, you'll also want to add gtest.framework to your "Link Binary with Libraries" build phase of your test target. In addition, you'll want to add the gtest.framework as a dependency to your unit test target. This way, Xcode will make sure that gtest.framework is up to date, every time your build your target. Finally, if you don't share build directories with Google Test, you'll have to copy the gtest.framework into your own build products directory using a "Run Script" build phase.
# Set Up the Executable Run Environment #
Since the unit test executable is a shell tool, it doesn't have a bundle with a `Contents/Frameworks` directory, in which to place gtest.framework. Instead, the dynamic linker must be told at runtime to search for the framework in another location. This can be accomplished by setting the "DYLD\_FRAMEWORK\_PATH" environment variable in the "Edit Active Executable ..." Arguments tab, under "Variables to be set in the environment:". The path for this value is the path (relative or absolute) of the directory containing the gtest.framework.
If you haven't set up the DYLD\_FRAMEWORK\_PATH, correctly, you might get a message like this:
```
[Session started at 2008-08-15 06:23:57 -0600.]
dyld: Library not loaded: @loader_path/../Frameworks/gtest.framework/Versions/A/gtest
Referenced from: /Users/username/Documents/Sandbox/gtestSample/build/Debug/WidgetFrameworkTest
Reason: image not found
```
To correct this problem, go to to the directory containing the executable named in "Referenced from:" value in the error message above. Then, with the terminal in this location, find the relative path to the directory containing the gtest.framework. That is the value you'll need to set as the DYLD\_FRAMEWORK\_PATH.
# Build and Go #
Now, when you click "Build and Go", the test will be executed. Dumping out something like this:
```
[Session started at 2008-08-06 06:36:13 -0600.]
[==========] Running 2 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 2 tests from WidgetInitializerTest
[ RUN ] WidgetInitializerTest.TestConstructor
[ OK ] WidgetInitializerTest.TestConstructor
[ RUN ] WidgetInitializerTest.TestConversion
[ OK ] WidgetInitializerTest.TestConversion
[----------] Global test environment tear-down
[==========] 2 tests from 1 test case ran.
[ PASSED ] 2 tests.
The Debugger has exited with status 0.
```
# Summary #
Unit testing is a valuable way to ensure your data model stays valid even during rapid development or refactoring. The Google Testing Framework is a great unit testing framework for C and C++ which integrates well with an Xcode development environment.

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# Googletest FAQ
## Why should test case names and test names not contain underscore?
Underscore (`_`) is special, as C++ reserves the following to be used by the
compiler and the standard library:
1. any identifier that starts with an `_` followed by an upper-case letter, and
1. any identifier that contains two consecutive underscores (i.e. `__`)
*anywhere* in its name.
User code is *prohibited* from using such identifiers.
Now let's look at what this means for `TEST` and `TEST_F`.
Currently `TEST(TestCaseName, TestName)` generates a class named
`TestCaseName_TestName_Test`. What happens if `TestCaseName` or `TestName`
contains `_`?
1. If `TestCaseName` starts with an `_` followed by an upper-case letter (say,
`_Foo`), we end up with `_Foo_TestName_Test`, which is reserved and thus
invalid.
1. If `TestCaseName` ends with an `_` (say, `Foo_`), we get
`Foo__TestName_Test`, which is invalid.
1. If `TestName` starts with an `_` (say, `_Bar`), we get
`TestCaseName__Bar_Test`, which is invalid.
1. If `TestName` ends with an `_` (say, `Bar_`), we get
`TestCaseName_Bar__Test`, which is invalid.
So clearly `TestCaseName` and `TestName` cannot start or end with `_` (Actually,
`TestCaseName` can start with `_` -- as long as the `_` isn't followed by an
upper-case letter. But that's getting complicated. So for simplicity we just say
that it cannot start with `_`.).
It may seem fine for `TestCaseName` and `TestName` to contain `_` in the middle.
However, consider this:
```c++
TEST(Time, Flies_Like_An_Arrow) { ... }
TEST(Time_Flies, Like_An_Arrow) { ... }
```
Now, the two `TEST`s will both generate the same class
(`Time_Flies_Like_An_Arrow_Test`). That's not good.
So for simplicity, we just ask the users to avoid `_` in `TestCaseName` and
`TestName`. The rule is more constraining than necessary, but it's simple and
easy to remember. It also gives googletest some wiggle room in case its
implementation needs to change in the future.
If you violate the rule, there may not be immediate consequences, but your test
may (just may) break with a new compiler (or a new version of the compiler you
are using) or with a new version of googletest. Therefore it's best to follow
the rule.
## Why does googletest support `EXPECT_EQ(NULL, ptr)` and `ASSERT_EQ(NULL, ptr)` but not `EXPECT_NE(NULL, ptr)` and `ASSERT_NE(NULL, ptr)`?
First of all you can use `EXPECT_NE(nullptr, ptr)` and `ASSERT_NE(nullptr,
ptr)`. This is the preferred syntax in the style guide because nullptr does not
have the type problems that NULL does. Which is why NULL does not work.
Due to some peculiarity of C++, it requires some non-trivial template meta
programming tricks to support using `NULL` as an argument of the `EXPECT_XX()`
and `ASSERT_XX()` macros. Therefore we only do it where it's most needed
(otherwise we make the implementation of googletest harder to maintain and more
error-prone than necessary).
The `EXPECT_EQ()` macro takes the *expected* value as its first argument and the
*actual* value as the second. It's reasonable that someone wants to write
`EXPECT_EQ(NULL, some_expression)`, and this indeed was requested several times.
Therefore we implemented it.
The need for `EXPECT_NE(NULL, ptr)` isn't nearly as strong. When the assertion
fails, you already know that `ptr` must be `NULL`, so it doesn't add any
information to print `ptr` in this case. That means `EXPECT_TRUE(ptr != NULL)`
works just as well.
If we were to support `EXPECT_NE(NULL, ptr)`, for consistency we'll have to
support `EXPECT_NE(ptr, NULL)` as well, as unlike `EXPECT_EQ`, we don't have a
convention on the order of the two arguments for `EXPECT_NE`. This means using
the template meta programming tricks twice in the implementation, making it even
harder to understand and maintain. We believe the benefit doesn't justify the
cost.
Finally, with the growth of the gMock matcher library, we are encouraging people
to use the unified `EXPECT_THAT(value, matcher)` syntax more often in tests. One
significant advantage of the matcher approach is that matchers can be easily
combined to form new matchers, while the `EXPECT_NE`, etc, macros cannot be
easily combined. Therefore we want to invest more in the matchers than in the
`EXPECT_XX()` macros.
## I need to test that different implementations of an interface satisfy some common requirements. Should I use typed tests or value-parameterized tests?
For testing various implementations of the same interface, either typed tests or
value-parameterized tests can get it done. It's really up to you the user to
decide which is more convenient for you, depending on your particular case. Some
rough guidelines:
* Typed tests can be easier to write if instances of the different
implementations can be created the same way, modulo the type. For example,
if all these implementations have a public default constructor (such that
you can write `new TypeParam`), or if their factory functions have the same
form (e.g. `CreateInstance<TypeParam>()`).
* Value-parameterized tests can be easier to write if you need different code
patterns to create different implementations' instances, e.g. `new Foo` vs
`new Bar(5)`. To accommodate for the differences, you can write factory
function wrappers and pass these function pointers to the tests as their
parameters.
* When a typed test fails, the output includes the name of the type, which can
help you quickly identify which implementation is wrong. Value-parameterized
tests cannot do this, so there you'll have to look at the iteration number
to know which implementation the failure is from, which is less direct.
* If you make a mistake writing a typed test, the compiler errors can be
harder to digest, as the code is templatized.
* When using typed tests, you need to make sure you are testing against the
interface type, not the concrete types (in other words, you want to make
sure `implicit_cast<MyInterface*>(my_concrete_impl)` works, not just that
`my_concrete_impl` works). It's less likely to make mistakes in this area
when using value-parameterized tests.
I hope I didn't confuse you more. :-) If you don't mind, I'd suggest you to give
both approaches a try. Practice is a much better way to grasp the subtle
differences between the two tools. Once you have some concrete experience, you
can much more easily decide which one to use the next time.
## My death tests became very slow - what happened?
In August 2008 we had to switch the default death test style from `fast` to
`threadsafe`, as the former is no longer safe now that threaded logging is the
default. This caused many death tests to slow down. Unfortunately this change
was necessary.
Please read [Fixing Failing Death Tests](death_test_styles.md) for what you can
do.
## I got some run-time errors about invalid proto descriptors when using `ProtocolMessageEquals`. Help!
**Note:** `ProtocolMessageEquals` and `ProtocolMessageEquiv` are *deprecated*
now. Please use `EqualsProto`, etc instead.
`ProtocolMessageEquals` and `ProtocolMessageEquiv` were redefined recently and
are now less tolerant on invalid protocol buffer definitions. In particular, if
you have a `foo.proto` that doesn't fully qualify the type of a protocol message
it references (e.g. `message<Bar>` where it should be `message<blah.Bar>`), you
will now get run-time errors like:
```
... descriptor.cc:...] Invalid proto descriptor for file "path/to/foo.proto":
... descriptor.cc:...] blah.MyMessage.my_field: ".Bar" is not defined.
```
If you see this, your `.proto` file is broken and needs to be fixed by making
the types fully qualified. The new definition of `ProtocolMessageEquals` and
`ProtocolMessageEquiv` just happen to reveal your bug.
## My death test modifies some state, but the change seems lost after the death test finishes. Why?
Death tests (`EXPECT_DEATH`, etc) are executed in a sub-process s.t. the
expected crash won't kill the test program (i.e. the parent process). As a
result, any in-memory side effects they incur are observable in their respective
sub-processes, but not in the parent process. You can think of them as running
in a parallel universe, more or less.
In particular, if you use [gMock](../../googlemock) and the death test statement
invokes some mock methods, the parent process will think the calls have never
occurred. Therefore, you may want to move your `EXPECT_CALL` statements inside
the `EXPECT_DEATH` macro.
## EXPECT_EQ(htonl(blah), blah_blah) generates weird compiler errors in opt mode. Is this a googletest bug?
Actually, the bug is in `htonl()`.
According to `'man htonl'`, `htonl()` is a *function*, which means it's valid to
use `htonl` as a function pointer. However, in opt mode `htonl()` is defined as
a *macro*, which breaks this usage.
Worse, the macro definition of `htonl()` uses a `gcc` extension and is *not*
standard C++. That hacky implementation has some ad hoc limitations. In
particular, it prevents you from writing `Foo<sizeof(htonl(x))>()`, where `Foo`
is a template that has an integral argument.
The implementation of `EXPECT_EQ(a, b)` uses `sizeof(... a ...)` inside a
template argument, and thus doesn't compile in opt mode when `a` contains a call
to `htonl()`. It is difficult to make `EXPECT_EQ` bypass the `htonl()` bug, as
the solution must work with different compilers on various platforms.
`htonl()` has some other problems as described in `//util/endian/endian.h`,
which defines `ghtonl()` to replace it. `ghtonl()` does the same thing `htonl()`
does, only without its problems. We suggest you to use `ghtonl()` instead of
`htonl()`, both in your tests and production code.
`//util/endian/endian.h` also defines `ghtons()`, which solves similar problems
in `htons()`.
Don't forget to add `//util/endian` to the list of dependencies in the `BUILD`
file wherever `ghtonl()` and `ghtons()` are used. The library consists of a
single header file and will not bloat your binary.
## The compiler complains about "undefined references" to some static const member variables, but I did define them in the class body. What's wrong?
If your class has a static data member:
```c++
// foo.h
class Foo {
...
static const int kBar = 100;
};
```
You also need to define it *outside* of the class body in `foo.cc`:
```c++
const int Foo::kBar; // No initializer here.
```
Otherwise your code is **invalid C++**, and may break in unexpected ways. In
particular, using it in googletest comparison assertions (`EXPECT_EQ`, etc) will
generate an "undefined reference" linker error. The fact that "it used to work"
doesn't mean it's valid. It just means that you were lucky. :-)
## Can I derive a test fixture from another?
Yes.
Each test fixture has a corresponding and same named test case. This means only
one test case can use a particular fixture. Sometimes, however, multiple test
cases may want to use the same or slightly different fixtures. For example, you
may want to make sure that all of a GUI library's test cases don't leak
important system resources like fonts and brushes.
In googletest, you share a fixture among test cases by putting the shared logic
in a base test fixture, then deriving from that base a separate fixture for each
test case that wants to use this common logic. You then use `TEST_F()` to write
tests using each derived fixture.
Typically, your code looks like this:
```c++
// Defines a base test fixture.
class BaseTest : public ::testing::Test {
protected:
...
};
// Derives a fixture FooTest from BaseTest.
class FooTest : public BaseTest {
protected:
void SetUp() override {
BaseTest::SetUp(); // Sets up the base fixture first.
... additional set-up work ...
}
void TearDown() override {
... clean-up work for FooTest ...
BaseTest::TearDown(); // Remember to tear down the base fixture
// after cleaning up FooTest!
}
... functions and variables for FooTest ...
};
// Tests that use the fixture FooTest.
TEST_F(FooTest, Bar) { ... }
TEST_F(FooTest, Baz) { ... }
... additional fixtures derived from BaseTest ...
```
If necessary, you can continue to derive test fixtures from a derived fixture.
googletest has no limit on how deep the hierarchy can be.
For a complete example using derived test fixtures, see [googletest
sample](https://github.com/google/googletest/blob/master/googletest/samples/sample5_unittest.cc)
## My compiler complains "void value not ignored as it ought to be." What does this mean?
You're probably using an `ASSERT_*()` in a function that doesn't return `void`.
`ASSERT_*()` can only be used in `void` functions, due to exceptions being
disabled by our build system. Please see more details
[here](advanced.md#assertion-placement).
## My death test hangs (or seg-faults). How do I fix it?
In googletest, death tests are run in a child process and the way they work is
delicate. To write death tests you really need to understand how they work.
Please make sure you have read [this](advanced.md#how-it-works).
In particular, death tests don't like having multiple threads in the parent
process. So the first thing you can try is to eliminate creating threads outside
of `EXPECT_DEATH()`. For example, you may want to use [mocks](../../googlemock)
or fake objects instead of real ones in your tests.
Sometimes this is impossible as some library you must use may be creating
threads before `main()` is even reached. In this case, you can try to minimize
the chance of conflicts by either moving as many activities as possible inside
`EXPECT_DEATH()` (in the extreme case, you want to move everything inside), or
leaving as few things as possible in it. Also, you can try to set the death test
style to `"threadsafe"`, which is safer but slower, and see if it helps.
If you go with thread-safe death tests, remember that they rerun the test
program from the beginning in the child process. Therefore make sure your
program can run side-by-side with itself and is deterministic.
In the end, this boils down to good concurrent programming. You have to make
sure that there is no race conditions or dead locks in your program. No silver
bullet - sorry!
## Should I use the constructor/destructor of the test fixture or SetUp()/TearDown()?
The first thing to remember is that googletest does **not** reuse the same test
fixture object across multiple tests. For each `TEST_F`, googletest will create
a **fresh** test fixture object, immediately call `SetUp()`, run the test body,
call `TearDown()`, and then delete the test fixture object.
When you need to write per-test set-up and tear-down logic, you have the choice
between using the test fixture constructor/destructor or `SetUp()/TearDown()`.
The former is usually preferred, as it has the following benefits:
* By initializing a member variable in the constructor, we have the option to
make it `const`, which helps prevent accidental changes to its value and
makes the tests more obviously correct.
* In case we need to subclass the test fixture class, the subclass'
constructor is guaranteed to call the base class' constructor *first*, and
the subclass' destructor is guaranteed to call the base class' destructor
*afterward*. With `SetUp()/TearDown()`, a subclass may make the mistake of
forgetting to call the base class' `SetUp()/TearDown()` or call them at the
wrong time.
You may still want to use `SetUp()/TearDown()` in the following rare cases:
* In the body of a constructor (or destructor), it's not possible to use the
`ASSERT_xx` macros. Therefore, if the set-up operation could cause a fatal
test failure that should prevent the test from running, it's necessary to
use a `CHECK` macro or to use `SetUp()` instead of a constructor.
* If the tear-down operation could throw an exception, you must use
`TearDown()` as opposed to the destructor, as throwing in a destructor leads
to undefined behavior and usually will kill your program right away. Note
that many standard libraries (like STL) may throw when exceptions are
enabled in the compiler. Therefore you should prefer `TearDown()` if you
want to write portable tests that work with or without exceptions.
* The googletest team is considering making the assertion macros throw on
platforms where exceptions are enabled (e.g. Windows, Mac OS, and Linux
client-side), which will eliminate the need for the user to propagate
failures from a subroutine to its caller. Therefore, you shouldn't use
googletest assertions in a destructor if your code could run on such a
platform.
* In a constructor or destructor, you cannot make a virtual function call on
this object. (You can call a method declared as virtual, but it will be
statically bound.) Therefore, if you need to call a method that will be
overridden in a derived class, you have to use `SetUp()/TearDown()`.
## The compiler complains "no matching function to call" when I use ASSERT_PRED*. How do I fix it?
If the predicate function you use in `ASSERT_PRED*` or `EXPECT_PRED*` is
overloaded or a template, the compiler will have trouble figuring out which
overloaded version it should use. `ASSERT_PRED_FORMAT*` and
`EXPECT_PRED_FORMAT*` don't have this problem.
If you see this error, you might want to switch to
`(ASSERT|EXPECT)_PRED_FORMAT*`, which will also give you a better failure
message. If, however, that is not an option, you can resolve the problem by
explicitly telling the compiler which version to pick.
For example, suppose you have
```c++
bool IsPositive(int n) {
return n > 0;
}
bool IsPositive(double x) {
return x > 0;
}
```
you will get a compiler error if you write
```c++
EXPECT_PRED1(IsPositive, 5);
```
However, this will work:
```c++
EXPECT_PRED1(static_cast<bool (*)(int)>(IsPositive), 5);
```
(The stuff inside the angled brackets for the `static_cast` operator is the type
of the function pointer for the `int`-version of `IsPositive()`.)
As another example, when you have a template function
```c++
template <typename T>
bool IsNegative(T x) {
return x < 0;
}
```
you can use it in a predicate assertion like this:
```c++
ASSERT_PRED1(IsNegative<int>, -5);
```
Things are more interesting if your template has more than one parameters. The
following won't compile:
```c++
ASSERT_PRED2(GreaterThan<int, int>, 5, 0);
```
as the C++ pre-processor thinks you are giving `ASSERT_PRED2` 4 arguments, which
is one more than expected. The workaround is to wrap the predicate function in
parentheses:
```c++
ASSERT_PRED2((GreaterThan<int, int>), 5, 0);
```
## My compiler complains about "ignoring return value" when I call RUN_ALL_TESTS(). Why?
Some people had been ignoring the return value of `RUN_ALL_TESTS()`. That is,
instead of
```c++
return RUN_ALL_TESTS();
```
they write
```c++
RUN_ALL_TESTS();
```
This is **wrong and dangerous**. The testing services needs to see the return
value of `RUN_ALL_TESTS()` in order to determine if a test has passed. If your
`main()` function ignores it, your test will be considered successful even if it
has a googletest assertion failure. Very bad.
We have decided to fix this (thanks to Michael Chastain for the idea). Now, your
code will no longer be able to ignore `RUN_ALL_TESTS()` when compiled with
`gcc`. If you do so, you'll get a compiler error.
If you see the compiler complaining about you ignoring the return value of
`RUN_ALL_TESTS()`, the fix is simple: just make sure its value is used as the
return value of `main()`.
But how could we introduce a change that breaks existing tests? Well, in this
case, the code was already broken in the first place, so we didn't break it. :-)
## My compiler complains that a constructor (or destructor) cannot return a value. What's going on?
Due to a peculiarity of C++, in order to support the syntax for streaming
messages to an `ASSERT_*`, e.g.
```c++
ASSERT_EQ(1, Foo()) << "blah blah" << foo;
```
we had to give up using `ASSERT*` and `FAIL*` (but not `EXPECT*` and
`ADD_FAILURE*`) in constructors and destructors. The workaround is to move the
content of your constructor/destructor to a private void member function, or
switch to `EXPECT_*()` if that works. This
[section](advanced.md#assertion-placement) in the user's guide explains it.
## My SetUp() function is not called. Why?
C++ is case-sensitive. Did you spell it as `Setup()`?
Similarly, sometimes people spell `SetUpTestCase()` as `SetupTestCase()` and
wonder why it's never called.
## How do I jump to the line of a failure in Emacs directly?
googletest's failure message format is understood by Emacs and many other IDEs,
like acme and XCode. If a googletest message is in a compilation buffer in
Emacs, then it's clickable.
## I have several test cases which share the same test fixture logic, do I have to define a new test fixture class for each of them? This seems pretty tedious.
You don't have to. Instead of
```c++
class FooTest : public BaseTest {};
TEST_F(FooTest, Abc) { ... }
TEST_F(FooTest, Def) { ... }
class BarTest : public BaseTest {};
TEST_F(BarTest, Abc) { ... }
TEST_F(BarTest, Def) { ... }
```
you can simply `typedef` the test fixtures:
```c++
typedef BaseTest FooTest;
TEST_F(FooTest, Abc) { ... }
TEST_F(FooTest, Def) { ... }
typedef BaseTest BarTest;
TEST_F(BarTest, Abc) { ... }
TEST_F(BarTest, Def) { ... }
```
## googletest output is buried in a whole bunch of LOG messages. What do I do?
The googletest output is meant to be a concise and human-friendly report. If
your test generates textual output itself, it will mix with the googletest
output, making it hard to read. However, there is an easy solution to this
problem.
Since `LOG` messages go to stderr, we decided to let googletest output go to
stdout. This way, you can easily separate the two using redirection. For
example:
```shell
$ ./my_test > gtest_output.txt
```
## Why should I prefer test fixtures over global variables?
There are several good reasons:
1. It's likely your test needs to change the states of its global variables.
This makes it difficult to keep side effects from escaping one test and
contaminating others, making debugging difficult. By using fixtures, each
test has a fresh set of variables that's different (but with the same
names). Thus, tests are kept independent of each other.
1. Global variables pollute the global namespace.
1. Test fixtures can be reused via subclassing, which cannot be done easily
with global variables. This is useful if many test cases have something in
common.
## What can the statement argument in ASSERT_DEATH() be?
`ASSERT_DEATH(*statement*, *regex*)` (or any death assertion macro) can be used
wherever `*statement*` is valid. So basically `*statement*` can be any C++
statement that makes sense in the current context. In particular, it can
reference global and/or local variables, and can be:
* a simple function call (often the case),
* a complex expression, or
* a compound statement.
Some examples are shown here:
```c++
// A death test can be a simple function call.
TEST(MyDeathTest, FunctionCall) {
ASSERT_DEATH(Xyz(5), "Xyz failed");
}
// Or a complex expression that references variables and functions.
TEST(MyDeathTest, ComplexExpression) {
const bool c = Condition();
ASSERT_DEATH((c ? Func1(0) : object2.Method("test")),
"(Func1|Method) failed");
}
// Death assertions can be used any where in a function. In
// particular, they can be inside a loop.
TEST(MyDeathTest, InsideLoop) {
// Verifies that Foo(0), Foo(1), ..., and Foo(4) all die.
for (int i = 0; i < 5; i++) {
EXPECT_DEATH_M(Foo(i), "Foo has \\d+ errors",
::testing::Message() << "where i is " << i);
}
}
// A death assertion can contain a compound statement.
TEST(MyDeathTest, CompoundStatement) {
// Verifies that at lease one of Bar(0), Bar(1), ..., and
// Bar(4) dies.
ASSERT_DEATH({
for (int i = 0; i < 5; i++) {
Bar(i);
}
},
"Bar has \\d+ errors");
}
```
gtest-death-test_test.cc contains more examples if you are interested.
## I have a fixture class `FooTest`, but `TEST_F(FooTest, Bar)` gives me error ``"no matching function for call to `FooTest::FooTest()'"``. Why?
Googletest needs to be able to create objects of your test fixture class, so it
must have a default constructor. Normally the compiler will define one for you.
However, there are cases where you have to define your own:
* If you explicitly declare a non-default constructor for class `FooTest`
(`DISALLOW_EVIL_CONSTRUCTORS()` does this), then you need to define a
default constructor, even if it would be empty.
* If `FooTest` has a const non-static data member, then you have to define the
default constructor *and* initialize the const member in the initializer
list of the constructor. (Early versions of `gcc` doesn't force you to
initialize the const member. It's a bug that has been fixed in `gcc 4`.)
## Why does ASSERT_DEATH complain about previous threads that were already joined?
With the Linux pthread library, there is no turning back once you cross the line
from single thread to multiple threads. The first time you create a thread, a
manager thread is created in addition, so you get 3, not 2, threads. Later when
the thread you create joins the main thread, the thread count decrements by 1,
but the manager thread will never be killed, so you still have 2 threads, which
means you cannot safely run a death test.
The new NPTL thread library doesn't suffer from this problem, as it doesn't
create a manager thread. However, if you don't control which machine your test
runs on, you shouldn't depend on this.
## Why does googletest require the entire test case, instead of individual tests, to be named *DeathTest when it uses ASSERT_DEATH?
googletest does not interleave tests from different test cases. That is, it runs
all tests in one test case first, and then runs all tests in the next test case,
and so on. googletest does this because it needs to set up a test case before
the first test in it is run, and tear it down afterwords. Splitting up the test
case would require multiple set-up and tear-down processes, which is inefficient
and makes the semantics unclean.
If we were to determine the order of tests based on test name instead of test
case name, then we would have a problem with the following situation:
```c++
TEST_F(FooTest, AbcDeathTest) { ... }
TEST_F(FooTest, Uvw) { ... }
TEST_F(BarTest, DefDeathTest) { ... }
TEST_F(BarTest, Xyz) { ... }
```
Since `FooTest.AbcDeathTest` needs to run before `BarTest.Xyz`, and we don't
interleave tests from different test cases, we need to run all tests in the
`FooTest` case before running any test in the `BarTest` case. This contradicts
with the requirement to run `BarTest.DefDeathTest` before `FooTest.Uvw`.
## But I don't like calling my entire test case \*DeathTest when it contains both death tests and non-death tests. What do I do?
You don't have to, but if you like, you may split up the test case into
`FooTest` and `FooDeathTest`, where the names make it clear that they are
related:
```c++
class FooTest : public ::testing::Test { ... };
TEST_F(FooTest, Abc) { ... }
TEST_F(FooTest, Def) { ... }
using FooDeathTest = FooTest;
TEST_F(FooDeathTest, Uvw) { ... EXPECT_DEATH(...) ... }
TEST_F(FooDeathTest, Xyz) { ... ASSERT_DEATH(...) ... }
```
## googletest prints the LOG messages in a death test's child process only when the test fails. How can I see the LOG messages when the death test succeeds?
Printing the LOG messages generated by the statement inside `EXPECT_DEATH()`
makes it harder to search for real problems in the parent's log. Therefore,
googletest only prints them when the death test has failed.
If you really need to see such LOG messages, a workaround is to temporarily
break the death test (e.g. by changing the regex pattern it is expected to
match). Admittedly, this is a hack. We'll consider a more permanent solution
after the fork-and-exec-style death tests are implemented.
## The compiler complains about "no match for 'operator<<'" when I use an assertion. What gives?
If you use a user-defined type `FooType` in an assertion, you must make sure
there is an `std::ostream& operator<<(std::ostream&, const FooType&)` function
defined such that we can print a value of `FooType`.
In addition, if `FooType` is declared in a name space, the `<<` operator also
needs to be defined in the *same* name space. See go/totw/49 for details.
## How do I suppress the memory leak messages on Windows?
Since the statically initialized googletest singleton requires allocations on
the heap, the Visual C++ memory leak detector will report memory leaks at the
end of the program run. The easiest way to avoid this is to use the
`_CrtMemCheckpoint` and `_CrtMemDumpAllObjectsSince` calls to not report any
statically initialized heap objects. See MSDN for more details and additional
heap check/debug routines.
## How can my code detect if it is running in a test?
If you write code that sniffs whether it's running in a test and does different
things accordingly, you are leaking test-only logic into production code and
there is no easy way to ensure that the test-only code paths aren't run by
mistake in production. Such cleverness also leads to
[Heisenbugs](https://en.wikipedia.org/wiki/Heisenbug). Therefore we strongly
advise against the practice, and googletest doesn't provide a way to do it.
In general, the recommended way to cause the code to behave differently under
test is [Dependency Injection](https://en.wikipedia.org/wiki/Dependency_injection). You can inject
different functionality from the test and from the production code. Since your
production code doesn't link in the for-test logic at all (the
[`testonly`](https://docs.bazel.build/versions/master/be/common-definitions.html#common.testonly)
attribute for BUILD targets helps to ensure that), there is no danger in
accidentally running it.
However, if you *really*, *really*, *really* have no choice, and if you follow
the rule of ending your test program names with `_test`, you can use the
*horrible* hack of sniffing your executable name (`argv[0]` in `main()`) to know
whether the code is under test.
## How do I temporarily disable a test?
If you have a broken test that you cannot fix right away, you can add the
DISABLED_ prefix to its name. This will exclude it from execution. This is
better than commenting out the code or using #if 0, as disabled tests are still
compiled (and thus won't rot).
To include disabled tests in test execution, just invoke the test program with
the --gtest_also_run_disabled_tests flag.
## Is it OK if I have two separate `TEST(Foo, Bar)` test methods defined in different namespaces?
Yes.
The rule is **all test methods in the same test case must use the same fixture
class.** This means that the following is **allowed** because both tests use the
same fixture class (`::testing::Test`).
```c++
namespace foo {
TEST(CoolTest, DoSomething) {
SUCCEED();
}
} // namespace foo
namespace bar {
TEST(CoolTest, DoSomething) {
SUCCEED();
}
} // namespace bar
```
However, the following code is **not allowed** and will produce a runtime error
from googletest because the test methods are using different test fixture
classes with the same test case name.
```c++
namespace foo {
class CoolTest : public ::testing::Test {}; // Fixture foo::CoolTest
TEST_F(CoolTest, DoSomething) {
SUCCEED();
}
} // namespace foo
namespace bar {
class CoolTest : public ::testing::Test {}; // Fixture: bar::CoolTest
TEST_F(CoolTest, DoSomething) {
SUCCEED();
}
} // namespace bar
```

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# Googletest Primer
## Introduction: Why googletest?
*googletest* helps you write better C++ tests.
googletest is a testing framework developed by the Testing
Technology team with Google's specific
requirements and constraints in mind. No matter whether you work on Linux,
Windows, or a Mac, if you write C++ code, googletest can help you. And it
supports *any* kind of tests, not just unit tests.
So what makes a good test, and how does googletest fit in? We believe:
1. Tests should be *independent* and *repeatable*. It's a pain to debug a test
that succeeds or fails as a result of other tests. googletest isolates the
tests by running each of them on a different object. When a test fails,
googletest allows you to run it in isolation for quick debugging.
1. Tests should be well *organized* and reflect the structure of the tested
code. googletest groups related tests into test cases that can share data
and subroutines. This common pattern is easy to recognize and makes tests
easy to maintain. Such consistency is especially helpful when people switch
projects and start to work on a new code base.
1. Tests should be *portable* and *reusable*. Google has a lot of code that is
platform-neutral, its tests should also be platform-neutral. googletest
works on different OSes, with different compilers (gcc, icc, and MSVC), with
or without exceptions, so googletest tests can easily work with a variety of
configurations.
1. When tests fail, they should provide as much *information* about the problem
as possible. googletest doesn't stop at the first test failure. Instead, it
only stops the current test and continues with the next. You can also set up
tests that report non-fatal failures after which the current test continues.
Thus, you can detect and fix multiple bugs in a single run-edit-compile
cycle.
1. The testing framework should liberate test writers from housekeeping chores
and let them focus on the test *content*. googletest automatically keeps
track of all tests defined, and doesn't require the user to enumerate them
in order to run them.
1. Tests should be *fast*. With googletest, you can reuse shared resources
across tests and pay for the set-up/tear-down only once, without making
tests depend on each other.
Since googletest is based on the popular xUnit architecture, you'll feel right
at home if you've used JUnit or PyUnit before. If not, it will take you about 10
minutes to learn the basics and get started. So let's go!
## Beware of the nomenclature
_Note:_ There might be some confusion of idea due to different
definitions of the terms _Test_, _Test Case_ and _Test Suite_, so beware
of misunderstanding these.
Historically, googletest started to use the term _Test Case_ for grouping
related tests, whereas current publications including the International Software
Testing Qualifications Board ([ISTQB](http://www.istqb.org/)) and various
textbooks on Software Quality use the term _[Test
Suite](http://glossary.istqb.org/search/test%20suite)_ for this.
The related term _Test_, as it is used in the googletest, is corresponding to
the term _[Test Case](http://glossary.istqb.org/search/test%20case)_ of ISTQB
and others.
The term _Test_ is commonly of broad enough sense, including ISTQB's
definition of _Test Case_, so it's not much of a problem here. But the
term _Test Case_ as used in Google Test is of contradictory sense and thus confusing.
Unfortunately replacing the term _Test Case_ by _Test Suite_ throughout the
googletest is not easy without breaking dependent projects, as `TestCase` is
part of the public API at various places.
So for the time being, please be aware of the different definitions of
the terms:
Meaning | googletest Term | [ISTQB](http://www.istqb.org/) Term
:----------------------------------------------------------------------------------- | :--------------------------------------------------------------------------------------------------------- | :----------------------------------
Exercise a particular program path with specific input values and verify the results | [TEST()](#simple-tests) | [Test Case](http://glossary.istqb.org/search/test%20case)
A set of several tests related to one component | [TestCase](#basic-concepts) | [TestSuite](http://glossary.istqb.org/search/test%20suite)
## Basic Concepts
When using googletest, you start by writing *assertions*, which are statements
that check whether a condition is true. An assertion's result can be *success*,
*nonfatal failure*, or *fatal failure*. If a fatal failure occurs, it aborts the
current function; otherwise the program continues normally.
*Tests* use assertions to verify the tested code's behavior. If a test crashes
or has a failed assertion, then it *fails*; otherwise it *succeeds*.
A *test case* contains one or many tests. You should group your tests into test
cases that reflect the structure of the tested code. When multiple tests in a
test case need to share common objects and subroutines, you can put them into a
*test fixture* class.
A *test program* can contain multiple test cases.
We'll now explain how to write a test program, starting at the individual
assertion level and building up to tests and test cases.
## Assertions
googletest assertions are macros that resemble function calls. You test a class
or function by making assertions about its behavior. When an assertion fails,
googletest prints the assertion's source file and line number location, along
with a failure message. You may also supply a custom failure message which will
be appended to googletest's message.
The assertions come in pairs that test the same thing but have different effects
on the current function. `ASSERT_*` versions generate fatal failures when they
fail, and **abort the current function**. `EXPECT_*` versions generate nonfatal
failures, which don't abort the current function. Usually `EXPECT_*` are
preferred, as they allow more than one failure to be reported in a test.
However, you should use `ASSERT_*` if it doesn't make sense to continue when the
assertion in question fails.
Since a failed `ASSERT_*` returns from the current function immediately,
possibly skipping clean-up code that comes after it, it may cause a space leak.
Depending on the nature of the leak, it may or may not be worth fixing - so keep
this in mind if you get a heap checker error in addition to assertion errors.
To provide a custom failure message, simply stream it into the macro using the
`<<` operator, or a sequence of such operators. An example:
```c++
ASSERT_EQ(x.size(), y.size()) << "Vectors x and y are of unequal length";
for (int i = 0; i < x.size(); ++i) {
EXPECT_EQ(x[i], y[i]) << "Vectors x and y differ at index " << i;
}
```
Anything that can be streamed to an `ostream` can be streamed to an assertion
macro--in particular, C strings and `string` objects. If a wide string
(`wchar_t*`, `TCHAR*` in `UNICODE` mode on Windows, or `std::wstring`) is
streamed to an assertion, it will be translated to UTF-8 when printed.
### Basic Assertions
These assertions do basic true/false condition testing.
Fatal assertion | Nonfatal assertion | Verifies
-------------------------- | -------------------------- | --------------------
`ASSERT_TRUE(condition);` | `EXPECT_TRUE(condition);` | `condition` is true
`ASSERT_FALSE(condition);` | `EXPECT_FALSE(condition);` | `condition` is false
Remember, when they fail, `ASSERT_*` yields a fatal failure and returns from the
current function, while `EXPECT_*` yields a nonfatal failure, allowing the
function to continue running. In either case, an assertion failure means its
containing test fails.
**Availability**: Linux, Windows, Mac.
### Binary Comparison
This section describes assertions that compare two values.
Fatal assertion | Nonfatal assertion | Verifies
------------------------ | ------------------------ | --------------
`ASSERT_EQ(val1, val2);` | `EXPECT_EQ(val1, val2);` | `val1 == val2`
`ASSERT_NE(val1, val2);` | `EXPECT_NE(val1, val2);` | `val1 != val2`
`ASSERT_LT(val1, val2);` | `EXPECT_LT(val1, val2);` | `val1 < val2`
`ASSERT_LE(val1, val2);` | `EXPECT_LE(val1, val2);` | `val1 <= val2`
`ASSERT_GT(val1, val2);` | `EXPECT_GT(val1, val2);` | `val1 > val2`
`ASSERT_GE(val1, val2);` | `EXPECT_GE(val1, val2);` | `val1 >= val2`
Value arguments must be comparable by the assertion's comparison operator or
you'll get a compiler error. We used to require the arguments to support the
`<<` operator for streaming to an `ostream`, but it's no longer necessary. If
`<<` is supported, it will be called to print the arguments when the assertion
fails; otherwise googletest will attempt to print them in the best way it can.
For more details and how to customize the printing of the arguments, see
gMock [recipe](../../googlemock/docs/CookBook.md#teaching-google-mock-how-to-print-your-values).).
These assertions can work with a user-defined type, but only if you define the
corresponding comparison operator (e.g. `==`, `<`, etc). Since this is
discouraged by the Google [C++ Style
Guide](https://google.github.io/styleguide/cppguide.html#Operator_Overloading),
you may need to use `ASSERT_TRUE()` or `EXPECT_TRUE()` to assert the equality of
two objects of a user-defined type.
However, when possible, `ASSERT_EQ(actual, expected)` is preferred to
`ASSERT_TRUE(actual == expected)`, since it tells you `actual` and `expected`'s
values on failure.
Arguments are always evaluated exactly once. Therefore, it's OK for the
arguments to have side effects. However, as with any ordinary C/C++ function,
the arguments' evaluation order is undefined (i.e. the compiler is free to
choose any order) and your code should not depend on any particular argument
evaluation order.
`ASSERT_EQ()` does pointer equality on pointers. If used on two C strings, it
tests if they are in the same memory location, not if they have the same value.
Therefore, if you want to compare C strings (e.g. `const char*`) by value, use
`ASSERT_STREQ()`, which will be described later on. In particular, to assert
that a C string is `NULL`, use `ASSERT_STREQ(c_string, NULL)`. Consider use
`ASSERT_EQ(c_string, nullptr)` if c++11 is supported. To compare two `string`
objects, you should use `ASSERT_EQ`.
When doing pointer comparisons use `*_EQ(ptr, nullptr)` and `*_NE(ptr, nullptr)`
instead of `*_EQ(ptr, NULL)` and `*_NE(ptr, NULL)`. This is because `nullptr` is
typed while `NULL` is not. See [FAQ](faq.md#why-does-google-test-support-expect_eqnull-ptr-and-assert_eqnull-ptr-but-not-expect_nenull-ptr-and-assert_nenull-ptr)
for more details.
If you're working with floating point numbers, you may want to use the floating
point variations of some of these macros in order to avoid problems caused by
rounding. See [Advanced googletest Topics](advanced.md) for details.
Macros in this section work with both narrow and wide string objects (`string`
and `wstring`).
**Availability**: Linux, Windows, Mac.
**Historical note**: Before February 2016 `*_EQ` had a convention of calling it
as `ASSERT_EQ(expected, actual)`, so lots of existing code uses this order. Now
`*_EQ` treats both parameters in the same way.
### String Comparison
The assertions in this group compare two **C strings**. If you want to compare
two `string` objects, use `EXPECT_EQ`, `EXPECT_NE`, and etc instead.
| Fatal assertion | Nonfatal assertion | Verifies |
| ------------------------------- | ------------------------------- | -------------------------------------------------------- |
| `ASSERT_STREQ(str1, str2);` | `EXPECT_STREQ(str1, str2);` | the two C strings have the same content |
| `ASSERT_STRNE(str1, str2);` | `EXPECT_STRNE(str1, str2);` | the two C strings have different contents |
| `ASSERT_STRCASEEQ(str1, str2);` | `EXPECT_STRCASEEQ(str1, str2);` | the two C strings have the same content, ignoring case |
| `ASSERT_STRCASENE(str1, str2);` | `EXPECT_STRCASENE(str1, str2);` | the two C strings have different contents, ignoring case |
Note that "CASE" in an assertion name means that case is ignored. A `NULL`
pointer and an empty string are considered *different*.
`*STREQ*` and `*STRNE*` also accept wide C strings (`wchar_t*`). If a comparison
of two wide strings fails, their values will be printed as UTF-8 narrow strings.
**Availability**: Linux, Windows, Mac.
**See also**: For more string comparison tricks (substring, prefix, suffix, and
regular expression matching, for example), see
[this](https://github.com/google/googletest/blob/master/googletest/docs/advanced.md)
in the Advanced googletest Guide.
## Simple Tests
To create a test:
1. Use the `TEST()` macro to define and name a test function, These are
ordinary C++ functions that don't return a value.
1. In this function, along with any valid C++ statements you want to include,
use the various googletest assertions to check values.
1. The test's result is determined by the assertions; if any assertion in the
test fails (either fatally or non-fatally), or if the test crashes, the
entire test fails. Otherwise, it succeeds.
```c++
TEST(TestCaseName, TestName) {
... test body ...
}
```
`TEST()` arguments go from general to specific. The *first* argument is the name
of the test case, and the *second* argument is the test's name within the test
case. Both names must be valid C++ identifiers, and they should not contain
underscore (`_`). A test's *full name* consists of its containing test case and
its individual name. Tests from different test cases can have the same
individual name.
For example, let's take a simple integer function:
```c++
int Factorial(int n); // Returns the factorial of n
```
A test case for this function might look like:
```c++
// Tests factorial of 0.
TEST(FactorialTest, HandlesZeroInput) {
EXPECT_EQ(Factorial(0), 1);
}
// Tests factorial of positive numbers.
TEST(FactorialTest, HandlesPositiveInput) {
EXPECT_EQ(Factorial(1), 1);
EXPECT_EQ(Factorial(2), 2);
EXPECT_EQ(Factorial(3), 6);
EXPECT_EQ(Factorial(8), 40320);
}
```
googletest groups the test results by test cases, so logically-related tests
should be in the same test case; in other words, the first argument to their
`TEST()` should be the same. In the above example, we have two tests,
`HandlesZeroInput` and `HandlesPositiveInput`, that belong to the same test case
`FactorialTest`.
When naming your test cases and tests, you should follow the same convention as
for [naming functions and
classes](https://google.github.io/styleguide/cppguide.html#Function_Names).
**Availability**: Linux, Windows, Mac.
## Test Fixtures: Using the Same Data Configuration for Multiple Tests
If you find yourself writing two or more tests that operate on similar data, you
can use a *test fixture*. It allows you to reuse the same configuration of
objects for several different tests.
To create a fixture:
1. Derive a class from `::testing::Test` . Start its body with `protected:` as
we'll want to access fixture members from sub-classes.
1. Inside the class, declare any objects you plan to use.
1. If necessary, write a default constructor or `SetUp()` function to prepare
the objects for each test. A common mistake is to spell `SetUp()` as
**`Setup()`** with a small `u` - Use `override` in C++11 to make sure you
spelled it correctly
1. If necessary, write a destructor or `TearDown()` function to release any
resources you allocated in `SetUp()` . To learn when you should use the
constructor/destructor and when you should use `SetUp()/TearDown()`, read
this [FAQ](faq.md#should-i-use-the-constructordestructor-of-the-test-fixture-or-setupteardown) entry.
1. If needed, define subroutines for your tests to share.
When using a fixture, use `TEST_F()` instead of `TEST()` as it allows you to
access objects and subroutines in the test fixture:
```c++
TEST_F(TestCaseName, TestName) {
... test body ...
}
```
Like `TEST()`, the first argument is the test case name, but for `TEST_F()` this
must be the name of the test fixture class. You've probably guessed: `_F` is for
fixture.
Unfortunately, the C++ macro system does not allow us to create a single macro
that can handle both types of tests. Using the wrong macro causes a compiler
error.
Also, you must first define a test fixture class before using it in a
`TEST_F()`, or you'll get the compiler error "`virtual outside class
declaration`".
For each test defined with `TEST_F()` , googletest will create a *fresh* test
fixture at runtime, immediately initialize it via `SetUp()` , run the test,
clean up by calling `TearDown()` , and then delete the test fixture. Note that
different tests in the same test case have different test fixture objects, and
googletest always deletes a test fixture before it creates the next one.
googletest does **not** reuse the same test fixture for multiple tests. Any
changes one test makes to the fixture do not affect other tests.
As an example, let's write tests for a FIFO queue class named `Queue`, which has
the following interface:
```c++
template <typename E> // E is the element type.
class Queue {
public:
Queue();
void Enqueue(const E& element);
E* Dequeue(); // Returns NULL if the queue is empty.
size_t size() const;
...
};
```
First, define a fixture class. By convention, you should give it the name
`FooTest` where `Foo` is the class being tested.
```c++
class QueueTest : public ::testing::Test {
protected:
void SetUp() override {
q1_.Enqueue(1);
q2_.Enqueue(2);
q2_.Enqueue(3);
}
// void TearDown() override {}
Queue<int> q0_;
Queue<int> q1_;
Queue<int> q2_;
};
```
In this case, `TearDown()` is not needed since we don't have to clean up after
each test, other than what's already done by the destructor.
Now we'll write tests using `TEST_F()` and this fixture.
```c++
TEST_F(QueueTest, IsEmptyInitially) {
EXPECT_EQ(q0_.size(), 0);
}
TEST_F(QueueTest, DequeueWorks) {
int* n = q0_.Dequeue();
EXPECT_EQ(n, nullptr);
n = q1_.Dequeue();
ASSERT_NE(n, nullptr);
EXPECT_EQ(*n, 1);
EXPECT_EQ(q1_.size(), 0);
delete n;
n = q2_.Dequeue();
ASSERT_NE(n, nullptr);
EXPECT_EQ(*n, 2);
EXPECT_EQ(q2_.size(), 1);
delete n;
}
```
The above uses both `ASSERT_*` and `EXPECT_*` assertions. The rule of thumb is
to use `EXPECT_*` when you want the test to continue to reveal more errors after
the assertion failure, and use `ASSERT_*` when continuing after failure doesn't
make sense. For example, the second assertion in the `Dequeue` test is
=ASSERT_NE(nullptr, n)=, as we need to dereference the pointer `n` later, which
would lead to a segfault when `n` is `NULL`.
When these tests run, the following happens:
1. googletest constructs a `QueueTest` object (let's call it `t1` ).
1. `t1.SetUp()` initializes `t1` .
1. The first test ( `IsEmptyInitially` ) runs on `t1` .
1. `t1.TearDown()` cleans up after the test finishes.
1. `t1` is destructed.
1. The above steps are repeated on another `QueueTest` object, this time
running the `DequeueWorks` test.
**Availability**: Linux, Windows, Mac.
## Invoking the Tests
`TEST()` and `TEST_F()` implicitly register their tests with googletest. So,
unlike with many other C++ testing frameworks, you don't have to re-list all
your defined tests in order to run them.
After defining your tests, you can run them with `RUN_ALL_TESTS()` , which
returns `0` if all the tests are successful, or `1` otherwise. Note that
`RUN_ALL_TESTS()` runs *all tests* in your link unit -- they can be from
different test cases, or even different source files.
When invoked, the `RUN_ALL_TESTS()` macro:
1. Saves the state of all googletest flags
* Creates a test fixture object for the first test.
* Initializes it via `SetUp()`.
* Runs the test on the fixture object.
* Cleans up the fixture via `TearDown()`.
* Deletes the fixture.
* Restores the state of all googletest flags
* Repeats the above steps for the next test, until all tests have run.
If a fatal failure happens the subsequent steps will be skipped.
> IMPORTANT: You must **not** ignore the return value of `RUN_ALL_TESTS()`, or
> you will get a compiler error. The rationale for this design is that the
> automated testing service determines whether a test has passed based on its
> exit code, not on its stdout/stderr output; thus your `main()` function must
> return the value of `RUN_ALL_TESTS()`.
>
> Also, you should call `RUN_ALL_TESTS()` only **once**. Calling it more than
> once conflicts with some advanced googletest features (e.g. thread-safe [death
> tests](advanced#death-tests)) and thus is not supported.
**Availability**: Linux, Windows, Mac.
## Writing the main() Function
In `google3`, the simplest approach is to use the default main() function
provided by linking in `"//testing/base/public:gtest_main"`. If that doesn't
cover what you need, you should write your own main() function, which should
return the value of `RUN_ALL_TESTS()`. Link to `"//testing/base/public:gunit"`.
You can start from this boilerplate:
```c++
#include "this/package/foo.h"
#include "gtest/gtest.h"
namespace {
// The fixture for testing class Foo.
class FooTest : public ::testing::Test {
protected:
// You can remove any or all of the following functions if its body
// is empty.
FooTest() {
// You can do set-up work for each test here.
}
~FooTest() override {
// You can do clean-up work that doesn't throw exceptions here.
}
// If the constructor and destructor are not enough for setting up
// and cleaning up each test, you can define the following methods:
void SetUp() override {
// Code here will be called immediately after the constructor (right
// before each test).
}
void TearDown() override {
// Code here will be called immediately after each test (right
// before the destructor).
}
// Objects declared here can be used by all tests in the test case for Foo.
};
// Tests that the Foo::Bar() method does Abc.
TEST_F(FooTest, MethodBarDoesAbc) {
const std::string input_filepath = "this/package/testdata/myinputfile.dat";
const std::string output_filepath = "this/package/testdata/myoutputfile.dat";
Foo f;
EXPECT_EQ(f.Bar(input_filepath, output_filepath), 0);
}
// Tests that Foo does Xyz.
TEST_F(FooTest, DoesXyz) {
// Exercises the Xyz feature of Foo.
}
} // namespace
int main(int argc, char **argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
```
The `::testing::InitGoogleTest()` function parses the command line for
googletest flags, and removes all recognized flags. This allows the user to
control a test program's behavior via various flags, which we'll cover in
[AdvancedGuide](advanced.md). You **must** call this function before calling
`RUN_ALL_TESTS()`, or the flags won't be properly initialized.
On Windows, `InitGoogleTest()` also works with wide strings, so it can be used
in programs compiled in `UNICODE` mode as well.
But maybe you think that writing all those main() functions is too much work? We
agree with you completely and that's why Google Test provides a basic
implementation of main(). If it fits your needs, then just link your test with
gtest\_main library and you are good to go.
NOTE: `ParseGUnitFlags()` is deprecated in favor of `InitGoogleTest()`.
## Known Limitations
* Google Test is designed to be thread-safe. The implementation is thread-safe
on systems where the `pthreads` library is available. It is currently
_unsafe_ to use Google Test assertions from two threads concurrently on
other systems (e.g. Windows). In most tests this is not an issue as usually
the assertions are done in the main thread. If you want to help, you can
volunteer to implement the necessary synchronization primitives in
`gtest-port.h` for your platform.

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# Googletest Samples {#samples}
If you're like us, you'd like to look at [googletest
samples.](https://github.com/google/googletest/tree/master/googletest/samples)
The sample directory has a number of well-commented samples showing how to use a
variety of googletest features.
* Sample #1 shows the basic steps of using googletest to test C++ functions.
* Sample #2 shows a more complex unit test for a class with multiple member
functions.
* Sample #3 uses a test fixture.
* Sample #4 teaches you how to use googletest and `googletest.h` together to
get the best of both libraries.
* Sample #5 puts shared testing logic in a base test fixture, and reuses it in
derived fixtures.
* Sample #6 demonstrates type-parameterized tests.
* Sample #7 teaches the basics of value-parameterized tests.
* Sample #8 shows using `Combine()` in value-parameterized tests.
* Sample #9 shows use of the listener API to modify Google Test's console
output and the use of its reflection API to inspect test results.
* Sample #10 shows use of the listener API to implement a primitive memory
leak checker.