@Test
public void oneNullLiteralFromFile() throws Exception {

    final File source = folder.newFile();
    try (final PrintWriter writer = new PrintWriter(source)) {
        writer.println("class A {");
        writer.println("    private final String a = null;");
        writer.println("}");
    }
    Assert.assertThat(
        new JavaSourceFile(source).nulls().asList().size(),
        IsEqual.equalTo(1)
    );
}