FakeIt

Linux / GCC:

Linux / Clang:

MSVC:

FakeIt is a simple mocking framework for C++. It supports GCC, Clang and MS Visual C++.

FakeIt is written in C++11 and can be used for testing both C++11 and C++ projects.

struct SomeInterface {
    virtual int foo(int) = 0;
    virtual int bar(string) = 0;
};

// Instantiate a mock object.
Mock<SomeInterface> mock;

// Setup mock behavior.
When(Method(mock,foo)).Return(1); // Method mock.foo will return 1 once.

// Fetch the mock instance.
SomeInterface &i = mock.get();

// Will print "1". 
cout << i.foo(0);

Verify method invocation:

Mock<SomeInterface> mock;
		
When(Method(mock,foo)).Return(0);

SomeInterface &i = mock.get();

// Production code
i.foo(1);

// Verify method mock.foo was invoked.
Verify(Method(mock,foo));

// Verify method mock.foo was invoked with specific arguments.
Verify(Method(mock,foo).Using(1));

Checkout the Quickstart for many more examples!

The master branch has the stable version of FakeIt. Include the most suitable single header in your test project and you are good to go.

Features

• Packaged as a single header file.
• Very simple API based on the expressiveness of C++11.
• Supports all major compilers: GCC, Clang and MSC++.
• Easily integrated with GTest, MS Test and Boost Test.
• Expressive Arrange-Act-Assert syntax.
• Create mock classes or spy existing objects instantly in one simple line.
• No limitation on number of method arguments.
• Supports dynamic casting.

Installation

FakeIt is a header only framework. It does not require any installation. For extra simplicity fakeit is packaged as a single header file.

FakeIt is pre-configured to work with some of the major unit testing frameworks. A pre-configured version will use the assertions mechanism of the unit testing framework to integrate the generated error messages into the unit testing framework output.

If you don't find your unit testing framework on the list, simply use the standalone configuration.

Configurations' name

Here's the list of each unit testing framework FakeIt is pre-configured with and the name of the respective configuration to use if you want FakeIt to integrate with them (if your favorite unit testing framework is not on the list, simply use the standalone configuration):

• GoogleTest: gtest
• MSTest: mstest
• Boost.Test: boost
• Catch2: catch
• tpunit++: tpunit
• mettle: mettle
• Qt Test: qtest
• NUnit: nunit
• CUTE: cute
• doctest: doctest
• Without a unit test framework: standalone

Using a pre-packaged single header file

Pre-packaged single header versions of FakeIt are located under the single_header folder. Depending on the unit testing framework you use, simply add one of the pre-packaged versions to the include path of your test project:

• <fakeit_folder>/single_header/gtest
• <fakeit_folder>/single_header/mstest
• <fakeit_folder>/single_header/boost
• <fakeit_folder>/single_header/catch - (v2 and v3)
• <fakeit_folder>/single_header/tpunit
• <fakeit_folder>/single_header/mettle
• <fakeit_folder>/single_header/qtest
• <fakeit_folder>/single_header/nunit - (See caveats in config/nunit/fakeit_instance.hpp)
• <fakeit_folder>/single_header/cute
• <fakeit_folder>/single_header/doctest
• <fakeit_folder>/single_header/standalone - (if you don't use a unit testing framework)

For example, to use fakeit with Google Test simply add the single_header/gtest folder to the include path of your test project:

-I"<fakeit_folder>/single_header/gtest"

Using the source header files

Fakeit source code header files are located under the include foler. To use FakeIt directly from the source code all you need to do is to download the source files and add the include folder and the configuration folder of your choice to the include path of your project. For example:

• To use fakeit with Google Test add the include folder and the config/gtest folder to the include path of your test project:

-I"<fakeit_folder>/include" -I"<fakeit_folder>/config/gtest"

• For every other unit test framework (or for using FakeIt without a unit test framework), just replace gtest by the name of the configuration (see Configurations' name section for details).
• If you use FakeIt with NUnit in a managed Visual Studio C++/CLI project, note that it is useful to define your mocks in #pragma unmanaged sections so that you can use lambda expressions.

It is recommended to build and run the unit tests to make sure FakeIt fits your environment.

For GCC, it is recommended to build the test project with -O1 or -O0 flags. Some features of FakeIt may not work with stronger optimizations!!

Installing FakeIt with CMake

Clone the repository, cd into it then execute the following commands:

cmake -S . -B build -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
cmake --build build
cmake --install build

Replace <INSTALL_DIR> by the path of the directory where you want to install FakeIt.

Then in your project's CMakeLists.txt:

find_package(FakeIt REQUIRED)
[...]
target_link_libraries(<YOUR_TARGET> PRIVATE FakeIt::FakeIt-<CONFIG>)

Where <YOUR_TARGET> is the name of the target you want to link FakeIt with, and <CONFIG> is the name of the specific configuration you want to use (see Configurations' name section for details).

Then, when you'll invoke CMake's configure command, pass the argument -DFakeIt_ROOT=<INSTALL_DIR>, with <INSTALL_DIR> being the directory where you installed FakeIt.

Installing FakeIt through Conan

To use FakeIt with Conan, you'll need a conanfile.txt like this:

[requires]
fakeit/<VERSION>

[options]
fakeit:integration=<CONFIG>

Replace <VERSION> by the version of FakeIt you want to use, and <CONFIG> with the name of the configuration you want to use (see Configurations' name section for details).

Installing FakeIt through vcpkg

You can download and install fakeit using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
./vcpkg install fakeit

The fakeit port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Running the tests

Building and Running the Unit Tests with GCC

CC=gcc CXX=g++ cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DENABLE_TESTING=ON
cmake --build build -j

Run the tests by typing:

./build/tests/FakeIt_tests

Building and Running the Unit Tests with Clang

CC=clang CXX=clang++ cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug -DENABLE_TESTING=ON
cmake --build build -j

Run the tests by typing:

./build/tests/FakeIt_tests

Building and Running the Unit Tests with Visual Studio

cmake -S . -B build -G "Visual Studio 17 2022" -DENABLE_TESTING=ON
cmake --build build --config Debug -j

Run the tests by typing:

./build/tests/Debug/FakeIt_tests.exe

Limitations

• Currently only GCC, Clang and MSC++ are supported.
• On GCC, optimization flag O2 and O3 are not supported. You must compile the test project with -O1 or -O0.
• In MSC++, your project must have Edit And Continue debug mode on (https://msdn.microsoft.com/en-us/library/esaeyddf.aspx) which is same of /ZI compiler switch. If you don't use this, you will have exceptions mocking destructors (which includes unique_ptr and other smart pointers).
• Can't mock classes with multiple inheritance.
• Can't mock classes with virtual inheritance.
• Currently mocks are not thread safe.