Adding testing functionality using GoogleTest

[kazurem]

1. Using CMake's FetchContent Module, automated the fetch and build of GoogleTest.

# This block executes only if the user configures CMake with -DBUILD_TESTING=ON.
if(BUILD_TESTING)
    include(FetchContent)
    FetchContent_Declare(
        googletest
        GIT_REPOSITORY https://github.com/google/googletest.git
        # Use a specific stable commit or tag (like release-1.14.0) for reliability.
        GIT_TAG        52eb8108c5bdec04579160ae17225d66034bd723
        # Recommended: Add DOWNLOAD_EXTRACT_TIMESTAMP TRUE for build robustness (CMP0135).
    )

    # Makes the googletest targets (GTest::gtest, GTest::gtest_main, etc.) available 
    # for linking in subsequent targets (like mms-test).
    FetchContent_MakeAvailable(googletest)
endif()

2. Created a tests folder which will contain all the test files:

The CMakeLists.txt for the tests folder is:

# the test executable and related targets are only built when the user configures CMake with 
# -DBUILD_TESTING=ON (as defined in the root CMakeLists.txt and CTest module).
if(BUILD_TESTING)

    # Creates the binary file (e.g., mms-test.exe) that will run all unit tests.
    add_executable(mms-test MazeGen-Test.cpp)

    # Connects the test executable to the necessary compiled code.
    target_link_libraries(mms-test 
        PRIVATE 
            # Links to the GoogleTest main library, which provides the main() function 
            # to run the tests and the testing framework itself.
            GTest::gtest_main 

            # Links to your project's core logic library (defined in the root CMakeLists.txt).
            # This is essential for calling the functions that we want test.
            mms-core
    )

    # Includes GoogleTest-specific CMake macros. This is necessary for gtest_discover_tests.
    include(GoogleTest)

    # Searches the compiled executable (mms-test) for all defined tests (using TEST/TEST_F macros)
    # and registers them with CTest. This allows you to run tests using the 'ctest' command.
    gtest_discover_tests(mms-test)

endif()

3. Added a basic test to check if GTest is working fine or not:

//MazeGen.cpp
size_t MazeGen::exampleFunc() { return 42; }

//MazeGen-Test.cpp
#include "MazeGen.hpp"
#include <gtest/gtest.h>

TEST(TestTopic, TrivialEquality) { EXPECT_EQ(MazeGen::exampleFunc(), 42); }