return generatedSource;
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }

    public static <T extends NativeCompileSpec> Transformer<T, T> getHeaderToSourceFileTransformer(Class<T> type) {
        return new Transformer<T, T>() {
            @Override
            public T transform(T original) {
                List<File> newSourceFiles = new ArrayList<>();

        def headerDir = tmpDirProvider.createDir("headers")
        def sourceFile = headerDir.createFile("test.h")
        Transformer<CPCHCompileSpec, CPCHCompileSpec> transformer = PCHUtils.getHeaderToSourceFileTransformer(CPCHCompileSpec)
        def spec = Mock(CPCHCompileSpec) {
            getTempDir() >> tempDir
            getSourceFiles() >> [ sourceFile ]
        }

        when:

            @Override
            public T transform(T original) {
                List<Transformer<T, T>> transformers = new ArrayList<>();
                transformers.add(PCHUtils.getHeaderToSourceFileTransformer(type));
                transformers.add(addDefinitions(type));

                T next = original;
                for (Transformer<T, T> transformer : transformers) {