Beyond ctest_read_custom_files(): Alternative Approaches for CTest Configuration Management

Purpose

• These files, typically named CTestCustom.ctest or CTestCustom.cmake, provide a way to tailor CTest behavior without directly modifying the main CMakeLists.txt file.
• In CMake's CTest framework, ctest_read_custom_files() is used to incorporate custom test configuration settings defined in external files.

Functionality

• The contents of these custom files are processed when CTest is invoked, allowing for dynamic test configuration based on project requirements or environment variables.
• These files can contain various CTest commands (like ctest_test(), ctest_build(), etc.) to control the testing process.
• The command instructs CTest to search for and read the specified custom files from one or more directories.

Usage

ctest_read_custom_files(directory1 directory2 ...)

• Replace directory1, directory2, etc. with the actual paths to the directories containing your custom test configuration files (e.g., source/ctest_config).

Default Behavior

• If you don't explicitly use ctest_read_custom_files(), CTest searches for CTestCustom.ctest or CTestCustom.cmake files in the binary directory (where the executables are built) by default.

Benefits

• Allows for environment-specific test configurations (e.g., different test files or settings for different build environments).
• Makes the main CMakeLists.txt file cleaner and less cluttered with test-specific logic.
• Enhances modularity and reusability of test configurations.

Example

Imagine you have a source/ctest_config/CTestCustom.ctest file containing:

# Run all tests with valgrind memory checker
ctest_memcheck(ON)

# Exclude specific test from the test run
ctest_exclude_test(my_failing_test)

# Add custom test data files
ctest_copy_file(data1.txt ${CMAKE_CURRENT_BINARY_DIR})
ctest_copy_file(data2.txt ${CMAKE_CURRENT_BINARY_DIR})

Then, in your main CMakeLists.txt, you could incorporate these settings using:

enable_testing()
include(CTest)  # Include CTest module

# Use the custom configuration from source/ctest_config
ctest_read_custom_files(source/ctest_config)

add_test(NAME my_test my_test.cpp)

---

Directory Structure

project/
  CMakeLists.txt
  source/
    my_test.cpp
    my_test_data.txt
  build/  # Generated during build process
    debug/
      CTestCustom.ctest  # Custom config for Debug build
    release/
      CTestCustom.ctest  # Custom config for Release build

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
project(my_project)

enable_testing()
include(CTest)

# Read custom config based on build configuration
set(CMAKE_BUILD_TYPE "DEBUG")  # Or "RELEASE"
if(${CMAKE_BUILD_TYPE} STREQUAL "DEBUG")
  ctest_read_custom_files(${CMAKE_CURRENT_BINARY_DIR}/debug)
elseif(${CMAKE_BUILD_TYPE} STREQUAL "RELEASE")
  ctest_read_custom_files(${CMAKE_CURRENT_BINARY_DIR}/release)
else()
  message(WARNING "Unsupported build type: ${CMAKE_BUILD_TYPE}")
endif()

add_executable(my_test source/my_test.cpp)

# Additional test setup (if required)
add_test(NAME my_test_with_data COMMAND my_test ${CMAKE_CURRENT_BINARY_DIR}/my_test_data.txt)

debug/CTestCustom.ctest

# Run tests with memory checker in Debug builds
ctest_memcheck(ON)

# Copy custom test data for Debug
ctest_copy_file(source/my_test_data.txt ${CMAKE_CURRENT_BINARY_DIR})

release/CTestCustom.ctest

# Run tests faster in Release builds (e.g., disable memory checking)
ctest_memcheck(OFF)
ctest_options(-T Experimental)

# No custom test data for Release

This approach enables different testing behaviors based on the build configuration, providing more control over how tests are run in Debug vs. Release builds.

This example demonstrates how ctest_read_custom_files() can be used for a reusable test fixture:

Directory Structure

project/
  CMakeLists.txt
  source/
    common/
      test_fixture.h
      test_fixture.cpp
    my_test1.cpp
    my_test2.cpp
  build/  # Generated during build process
    CTestCustom.ctest  # Fixture setup

source/common/test_fixture.h

#ifndef TEST_FIXTURE_H
#define TEST_FIXTURE_H

class TestFixture {
public:
  virtual ~TestFixture() {}
  virtual void SetUp() {}
  virtual void TearDown() {}
};

#endif

source/common/test_fixture.cpp

#include "test_fixture.h"

class TestFixtureImpl : public TestFixture {
public:
  void SetUp() override {
    // Common setup logic for all tests using this fixture
  }

  void TearDown() override {
    // Common cleanup logic for all tests using this fixture
  }
};

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
project(my_project)

enable_testing()
include(CTest)

# Read fixture setup from custom file
ctest_read_custom_files(build)

find_package(CppUnit REQUIRED)

add_executable(my_test1 source/my_test1.cpp source/common/test_fixture.cpp)
add_executable(my_test2 source/my_test2.cpp source/common/test_fixture.cpp)

# Link tests with the fixture implementation
target_link_libraries(my_test1 PRIVATE CppUnit TestFixtureImpl)
target_link_libraries(my_test2 PRIVATE CppUnit TestFixtureImpl)

# Define tests using the fixture
ctest_register_test(my_test1_test my_test1)
ctest_register_test(my_test2_test my_test2)

# Fixture setup in CTestCustom.ctest

# Include test fixture implementation
include(${CMAKE_CURRENT_SOURCE_DIR}/source/common/test_fixture.cpp)

---

Conditional Logic in Main CMakeLists.txt

• Instead of separate files, you can use conditional logic within your main CMakeLists.txt file to configure tests based on variables or build configurations.

if(${CMAKE_BUILD_TYPE} STREQUAL "DEBUG")
  # Debug-specific test settings
  ctest_memcheck(ON)
else()
  # Release-specific test settings
  ctest_options(-T Experimental)
endif()

Use CMake Modules

• Include these modules in your CMakeLists.txt where needed.
• Create separate CMake modules (.cmake files) that encapsulate specific test configuration logic.

Directory Structure

project/
  CMakeLists.txt
  source/
    my_test.cpp
  test_config/
    debug_config.cmake
    release_config.cmake

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
project(my_project)

enable_testing()
include(CTest)

# Include test configuration based on build type
set(CMAKE_BUILD_TYPE "DEBUG")  # Or "RELEASE"
if(${CMAKE_BUILD_TYPE} STREQUAL "DEBUG")
  include(test_config/debug_config.cmake)
elseif(${CMAKE_BUILD_TYPE} STREQUAL "RELEASE")
  include(test_config/release_config.cmake)
else()
  message(WARNING "Unsupported build type: ${CMAKE_BUILD_TYPE}")
endif()

add_executable(my_test source/my_test.cpp)

# Add tests
add_test(NAME my_test COMMAND my_test)

test_config/debug_config.cmake

ctest_memcheck(ON)
# Add other Debug-specific test settings

test_config/release_config.cmake

ctest_options(-T Experimental)
# Add other Release-specific test settings

Custom CMake Commands

• These commands can be invoked from your CMakeLists.txt file.
• If your test configuration needs more complex logic, define custom CMake commands to handle those specific tasks.

Benefits of Alternatives

• They provide more organization and reusability of test configuration logic.
• These approaches can keep your main CMakeLists.txt file more concise and focused on core project setup.

• For more complex or modular setups, consider using CMake modules or custom commands.
• ctest_read_custom_files() is a simple and effective method for basic scenarios.
• The best approach depends on the complexity of your test configurations and your project's overall structure.