/** Asserts that value of the top-level field "x" in given source has the given type name. */
 private String assertType(String expectedTypeName, String[] lines) throws Exception {
   DartExpression expression = getMarkerVariableExpression(lines);
   String type = ExtractUtils.getTypeSource(expression);
   if (expectedTypeName != null) {
     assertNotNull(type);
     assertEquals(expectedTypeName, type);
   } else {
     assertNull(type);
   }
   return type;
 }
 public void test_getType_null() throws Exception {
   assertSame(null, ExtractUtils.getTypeSource((DartExpression) null));
 }