unittest: Update catch2 section

chapters/testing/unit_test.md

@@ -2,11 +2,98 @@
 
 ## Catch2
 
-[github.com/catchorg/Catch2](https://github.com/catchorg/Catch2)
+- [github.com/catchorg/Catch2](https://github.com/catchorg/Catch2)
+- [Example Project: tobanteAudio/juce-6-demo](https://github.com/tobanteAudio/juce-6-demo)
 
-- Link against CMake shared code target
-- Register tests
-- CTest
+### Include Catch2
+
+```cmake
+option(YOURPLUGIN_BUILD_TESTS "Build the unit tests with Catch2" ON)
+
+if(YOURPLUGIN_BUILD_TESTS)
+ list (APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/3rd_party/Catch2/contrib")
+ enable_testing()
+ add_subdirectory(3rd_party/Catch2 EXCLUDE_FROM_ALL)
+ include(CTest)
+ include(Catch)
+endif()
+```
+
+### Write Test
+
+#### main
+
+We need to write a custom main for Catch, since we need to initialize & shutdown JUCE.
+
+```cpp
+#include "JuceHeader.h"
+
+#define CATCH_CONFIG_RUNNER
+#include "catch2/catch.hpp"
+
+int main(int argc, char* argv[])
+{
+ juce::initialiseJuce_GUI();
+ int result = Catch::Session().run(argc, argv);
+ juce::shutdownJuce_GUI();
+ return result;
+}
+```
+
+#### processor
+
+Simple tests checking the plug-in name & if a mono bus layout is supported.
+
+```cpp
+#include "catch2/catch.hpp"
+
+#include "YourProcessor.hpp"
+
+TEST_CASE("processor: Name", "[processor]")
+{
+ auto processor = YourProcessor {};
+ REQUIRE(processor.getName() == juce::String {"Plugin Name"});
+}
+
+
+TEST_CASE("processor: BusesLayoutSupportMono", "[processor]")
+{
+ auto processor = YourProcessor {};
+ auto layout = juce::AudioProcessor::BusesLayout {};
+ layout.inputBuses = juce::AudioChannelSet::mono();
+ layout.outputBuses = juce::AudioChannelSet::mono();
+
+ REQUIRE(processor.isBusesLayoutSupported(layout));
+}
+
+```
+
+### Link against SharedCode
+
+Link the unit test target to the shared code of your plug-in.
+
+```cmake
+juce_add_plugin(YourPlugin ...)
+
+# ...
+
+if(YOURPLUGIN_BUILD_TESTS)
+ add_executable(YourPlugin_Tests)
+ target_sources(YourPlugin_Tests PRIVATE Source/main_test.cpp)
+ catch_discover_tests(YourPlugin_Tests)
+ target_link_libraries(YourPlugin_Tests PRIVATE YourPlugin Catch2::Catch2)
+endif()
+```
+
+### CTest
+
+After building run `ctest` inside your build directory.
+
+```sh
+cd $CMAKE_BUILD_DIR
+ctest -C Release # Release build
+ctest -C Debug # Debug build
+```
 
 ## JUCE Unit Tests