@Test
public void testEmptyBlock() throws Exception {

  final String program = "void main() { { } }";
  final TranslationUnit tu = ParseHelper.parse(program);
  List<UnwrapReductionOpportunity> ops = UnwrapReductionOpportunities
      .findOpportunities(MakeShaderJobFromFragmentShader.make(tu),
        new ReducerContext(false,
        ShadingLanguageVersion.GLSL_440, new SameValueRandom(false, 0),
            new IdGenerator()));
  // No opportunities because the inner block is empty.  Another reduction pass may be able to
  // delete it, but it cannot be unwrapped.
  assertEquals(0, ops.size());
}