### Question:
DesiredSourceFiles implements Desired<String, SourceFile> { @Override public SourceFile get(String id) { return sourceFiles().get(id); } DesiredSourceFiles(Document radl, SourceFilesGenerator generator, File baseDir); @Override Collection<String> getIds(); @Override SourceFile get(String id);  }### Answer:
@Test public void returnsSourceFile() throws Exception { SourceFile expected = new SourceFile(basePath + RANDOM.string()); when(generator.generateFrom(radl, new File(basePath))).thenReturn(Arrays.asList(expected)); SourceFile actual = desired.get(expected.path()); Assert.assertEquals("Source file", expected, actual); }