anchor.diff:  
   void main() {
     defineReflectiveSuite(() {
  +    defineReflectiveTests(RangeFactory_ArgumentRangeTest);
  +    defineReflectiveTests(RangeFactory_NodeInListTest);
       defineReflectiveTests(RangeFactoryTest);
     });
   }
   
   @reflectiveTest
  -class RangeFactoryTest extends AbstractSingleUnitTest {
  -  /// Assuming that the test code starts with a function whose block body starts
  -  /// with a method invocation, return the list of arguments in that invocation.
  -  NodeList<Expression> get _argumentList {
  -    var f = testUnit.declarations[0] as FunctionDeclaration;
  -    var body = f.functionExpression.body as BlockFunctionBody;
  -    var statement = body.block.statements[0] as ExpressionStatement;
  -    var invocation = statement.expression as MethodInvocation;
  -    return invocation.argumentList.arguments;
  -  }
  -
  -  Future<void> test_argumentRange_all_mixed_noTrailingComma() async {
  +class RangeFactory_ArgumentRangeTest extends AbstractSingleUnitTest {
  +  Future<void> test_all_mixed_noTrailingComma() async {
       await resolveTestCode('''
   void f() {
     g(0, 1, c: 2);
  
positive.code:     _assertArgumentRange(0, 0, SourceRange(15, 3), SourceRange(15, 1));
    }
  
    Future<void> test_argumentRange_last_noTrailingComma() async {
      await resolveTestCode('''
  void f() {
    g(0, 1);
  
negative.code:     _assertArgumentRange(0, 0, SourceRange(15, 4), SourceRange(15, 4));
    }
  
    Future<void> test_only_positional() async {
      await resolveTestCode('''
  void f() {
    g(0);
  