Additional considerations for create_test_sourcelist()

What is `create_test_sourcelist()`?

The create_test_sourcelist() command in CMake is used to generate a test driver and a source list for building test programs. Essentially, it helps to organize and manage multiple tests within a single executable, which can be beneficial for efficiency and reducing executable size, especially when dealing with large libraries.

How it Works

- The command creates a main function that acts as a test driver. This function iterates over the specified test source files and calls their respective test functions.
- You can customize the test driver behavior using the CMAKE_TESTDRIVER_BEFORE_TESTMAIN variable to add code that executes before each test.
Source List Creation
- The command generates a list of source files that will be compiled into the test executable. This list includes the test driver and the specified test source files.
Test Definition
- For each source file in the source list, an add_test() command is implicitly called to define the test. The test name is derived from the source file name.

Basic Usage

create_test_sourcelist(TEST_SOURCES
  test1.cpp
  test2.cpp
  test3.cpp
)

This code will:

Define tests named test1, test2, and test3
Include test1.cpp, test2.cpp, and test3.cpp in the test executable
Create a test driver named TEST_SOURCES

Key Points

You can customize the test driver behavior using CMAKE_TESTDRIVER_BEFORE_TESTMAIN.
The add_test() command is implicitly called for each test source file.
It generates a test driver and a source list automatically.
create_test_sourcelist() is primarily used for managing multiple tests within a single executable.

# Create a directory for test source files
add_subdirectory(tests)

# Create a test source list
create_test_sourcelist(MY_TESTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.cpp)

# Set custom code to execute before each test
set(CMAKE_TESTDRIVER_BEFORE_TESTMAIN "printf(\"Running test: %s\\n\", __func__);")

This example:

Sets custom code to print the test name before each test execution.
Generates a test source list named MY_TESTS including all .cpp files in the tests directory.
Creates a subdirectory named tests to hold test source files.

Additional Considerations

The create_test_sourcelist() command is often used in combination with other testing tools and practices.
You can use the add_test() command directly for individual tests if needed.
For more complex test setups, consider using testing frameworks like Google Test or Catch2.

By understanding the create_test_sourcelist() command and its role in CMake's testing capabilities, you can effectively organize and manage your test code for efficient and reliable testing.

Basic Example

# Create a directory for test source files
add_subdirectory(tests)

# Create a test source list
create_test_sourcelist(MY_TESTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.cpp)

# Add the executable
add_executable(MyTests ${MY_TESTS})

# Add tests (optional, as `create_test_sourcelist` implicitly adds them)
foreach(test ${MY_TESTS})
  get_filename_component(TName ${test} NAME_WE)
  add_test(NAME ${TName} COMMAND MyTests ${TName})
endforeach()

Example with Custom Test Driver and Test Setup

# Create a directory for test source files
add_subdirectory(tests)

# Create a test source list
create_test_sourcelist(MY_TESTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.cpp)

# Set custom code to execute before each test
set(CMAKE_TESTDRIVER_BEFORE_TESTMAIN "printf(\"Running test: %s\\n\", __func__);")

# Add the executable
add_executable(MyTests ${MY_TESTS})

# Add custom test setup code (optional)
add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/test_setup.cpp
  COMMAND echo "int test_setup() { /* your setup code here */ }" > ${CMAKE_CURRENT_BINARY_DIR}/test_setup.cpp)
list(APPEND MY_TESTS ${CMAKE_CURRENT_BINARY_DIR}/test_setup.cpp)

This example adds custom setup code to each test by creating a test_setup.cpp file and including it in the test source list. It also prints the test name before each test execution.

Example with Test Fixtures

# Create a directory for test source files
add_subdirectory(tests)

# Create a test source list
create_test_sourcelist(MY_TESTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.cpp)

# Add the executable
add_executable(MyTests ${MY_TESTS})

# Add tests with custom command-line arguments (optional)
foreach(test ${MY_TESTS})
  get_filename_component(TName ${test} NAME_WE)
  add_test(NAME ${TName} COMMAND MyTests ${TName} --some_argument)
endforeach()

This example shows how to pass custom arguments to each test using the add_test command.

# Create a directory for test source files
add_subdirectory(tests)

# Find Google Test (or other testing framework)
find_package(GoogleTest REQUIRED)

# Create a test source list
create_test_sourcelist(MY_TESTS ${CMAKE_CURRENT_SOURCE_DIR}/tests/*.cpp)

# Add the executable
add_executable(MyTests ${MY_TESTS} ${GoogleTest_SRC})
target_link_libraries(MyTests ${GoogleTest_LIBRARIES})

# Add tests using Google Test (or other testing framework)
# ... (code for using Google Test)

This example demonstrates how to integrate create_test_sourcelist with a testing framework like Google Test.

Explore the CMAKE_TESTDRIVER_BEFORE_TESTMAIN variable for further customization of the test driver.
Consider using a testing framework for more advanced test features and organization.
Adjust the file paths and test names according to your project structure.

Manual Test Executable Creation

Cons
More verbose and less flexible for large test suites.
Pros
Full control over executable content and build process.

Manage source files with lists

set(TEST_SOURCES test1.cpp test2.cpp test3.cpp)
add_executable(MyTests ${TEST_SOURCES})

Directly specify source files

add_executable(MyTests test1.cpp test2.cpp test3.cpp)

Using Testing Frameworks

Cons
Additional dependencies and learning curve.
Pros
Rich features, advanced test organization, and better test discovery.

Google Test, Catch2, etc.
These frameworks provide their own mechanisms for organizing and running tests.

find_package(GoogleTest REQUIRED)
add_executable(MyTests test1.cpp test2.cpp test3.cpp ${GoogleTest_SRC})
target_link_libraries(MyTests ${GoogleTest_LIBRARIES})

Custom CMake Functions

Cons
Requires additional CMake code development.
Pros
Customization and reusability.

Create a custom function to manage test sources and executables

function(add_test_executable name sources)
  add_executable(${name} ${sources})
  # Additional logic for test setup, discovery, etc.
endfunction()

Custom test requirements or specific project structure
A custom CMake function can be tailored.
Large test suites or complex test logic
A testing framework is recommended.
Small test suites
Manual creation might suffice.

Key Factors to Consider

Desired level of control
Manual creation offers more control, while frameworks provide abstractions.
Project structure
How tests are organized within your project.
Team familiarity
Using a popular framework can improve collaboration.
Test complexity
Simple unit tests might not require a full-fledged framework.

Additional Tips

Leverage ctest for test execution and reporting.
Explore CMake's foreach and list commands for flexible test management.
Consider using add_subdirectory to organize test code into separate directories.

By carefully evaluating these options and considering your project's specific needs, you can choose the most suitable approach for managing your tests in CMake.