implement an integration test suite

CMakeLists.txt

@@ -5,3 +5,14 @@ set(CMAKE_CXX_STANDARD 17)
 
 add_executable(ccolors main.cpp)
 
+# Phase 1: black-box integration test suite.
+enable_testing()
+find_package(Python3 COMPONENTS Interpreter)
+if(Python3_Interpreter_FOUND)
+    add_test(
+        NAME ccolors_integration
+        COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/test_runner.py
+                $<TARGET_FILE:ccolors>
+    )
+endif()
+