CI: apply schema-validation to the example config files

- Any config file with a schema gets a test (validate-<module>)
  to test the file.

src/modules/CMakeLists.txt

@@ -66,3 +66,21 @@ endforeach()
 
 include( CalamaresAddTranslations )
 add_calamares_python_translations( ${CALAMARES_TRANSLATION_LANGUAGES} )
+
+# TODO:3.3: Use FindPython3
+if ( BUILD_TESTING AND PYTHONINTERP_FOUND AND PYTHON_EXECUTABLE )
+    # The tests for each config file are independent of whether the
+    # module is enabled or not: the config file should match its schema
+    # regardless.
+    foreach( SUBDIRECTORY ${SUBDIRECTORIES} )
+        set( _schema_file "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIRECTORY}/${SUBDIRECTORY}.schema.yaml" )
+        set( _conf_file "${CMAKE_CURRENT_SOURCE_DIR}/${SUBDIRECTORY}/${SUBDIRECTORY}.conf" )
+        if ( EXISTS "${_schema_file}" AND EXISTS "${_conf_file}" )
+            add_test(
+                NAME validate-${SUBDIRECTORY}
+                COMMAND ${PYTHON_EXECUTABLE} "${CMAKE_SOURCE_DIR}/ci/configvalidator.py" "${_schema_file}" "${_conf_file}"
+            )
+        endif()
+    endforeach()
+endif()
+