anchor.diff:        };
         _expectParseThrows(monoYaml, r'''
   line 7, column 7: Stages are required to have at least one job. "a" is empty.
  -      "a": []
  -      ^^^''');
  +  ╷
  +7 │       "a": []
  +  │       ^^^
  +  ╵''');
       });
   
       test('multiple keys under a stage', () {
  
positive.code: 
        _expectParseThrows(monoYaml, r'''
  line 12, column 7: Stages muts be unique. "a" appears more than once.
        "a": [
        ^^^''');
      });
    });
  }
  
negative.code:       };
        _expectParseThrows(monoYaml, r'''
  line 8, column 7: `stages` expects a list of maps with exactly one key (the name of the stage), but the provided value has 2 values.
    ╷
  8 │       "b": null
    │       ^^^
    ╵''');
      });
  
      test('no keys under a stage', () {
  