void writeSources(TestFile mainSourceDir, TestFile librarySourceDir, TestFile greetingsLibrarySourceDir) {
        getExecutable().writeSources(mainSourceDir)
        getLibrary().writeSources(librarySourceDir)
        getGreetingsHeader().writeToDir(greetingsLibrarySourceDir)
        for (SourceFile sourceFile : greetingsSources) {
            sourceFile.writeToDir(greetingsLibrarySourceDir)
        }
    }