anchor.diff:  
         router.route('/foo/bar').then(expectAsync((_) {
           expect(counters, {
  -          'fooPreEnter': 1,
  +          'fooPreEnter': 1, // +1
             'fooPreLeave': 0,
  -          'fooEnter': 1,
  +          'fooEnter': 1,    // +1
             'fooLeave': 0,
             'barPreEnter': 0,
             'barPreLeave': 0,
  
positive.code: 
        router.route('/foo/bar').then(expectAsync((_) {
          expect(counters, {
            'fooPreEnter': 1,
            'fooPreLeave': 0,
            'fooEnter': 1,
            'fooLeave': 0,
            'barPreEnter': 0,
            'barPreLeave': 0,
  
negative.code: 
          router.route('/foo/bar').then(expectAsync((_) {
            expect(counters, {
              'fooPreEnter': 1,
              'fooPreLeave': 0,
              'fooEnter': 1,
              'fooLeave': 0,
              'barPreEnter': 0,
              'barPreLeave': 0,
              'barEnter': 0,
              'barLeave': 0
            });
  
            router.route('/foo/baz').then(expectAsync((_) {
              expect(counters, {
                'fooPreEnter': 2, // +1
                'fooPreLeave': 0,
                'fooEnter': 2,    // +1
                'fooLeave': 0,
                'barPreEnter': 0,
                'barPreLeave': 0,
                'barEnter': 0,
                'barLeave': 0
              });
  
              router.route('/bar').then(expectAsync((_) {
                expect(counters, {
                  'fooPreEnter': 2,
                  'fooPreLeave': 1, // +1
                  'fooEnter': 2,
                  'fooLeave': 1,    // +1
                  'barPreEnter': 1, // +1
                  'barPreLeave': 0,
                  'barEnter': 1,    // +1
                  'barLeave': 0
                });
              }));
            }));
  