anchor.diff:    var b = 'b';
     var c = 'c';
     print("""
  -a $b-${c} d""");
  +a $b - ${c} d""");
  +}
  +''');
  +  }
  +
  +  test_doubleQuoted_interpolation_stringElement_middle() async {
  +    await resolveTestUnit(r"""
  +main() {
  +  var b = 'b';
  +  var c = 'c';
  +  print("a $b - ${c} d");
  +}
  +""");
  +    await assertHasAssistAt('- ', r'''
  +main() {
  +  var b = 'b';
  +  var c = 'c';
  +  print("""
  +a $b - ${c} d""");
   }
   ''');
     }
  
positive.code:   var b = 'b';
    var c = 'c';
    print('''
  a $b-${c} d''');
  }
  """);
    }
  
negative.code:     await assertNoAssistAt('abc');
    }
  
    test_doubleQuoted_interpolation_expressionElement() async {
      await resolveTestUnit(r"""
  main() {
    var b = 'b';
    var c = 'c';
    print("a $b - ${c} d");
  }
  """);
      await assertNoAssistAt(r'c}');
    }
  
    test_doubleQuoted_interpolation_stringElement_begin() async {
      await resolveTestUnit(r"""
  main() {
    var b = 'b';
    var c = 'c';
    print("a $b - ${c} d");
  }
  """);
      await assertHasAssistAt('"a ', r'''
  