anchor.diff:            expect(() => attribute.extractValueAtRow(3), throwsRangeError);
           });
   
  -        test('returns the correct value with a valid index', () {
  -          expect(attribute.extractValueAtRow(1), equals(new Vector4(1.1, 1.2, 1.3, 1.4)));
  +        group('with a valid index', () {
  +          final value = attribute.extractValueAtRow(1);
  +
  +          test('returns a Vector4 instance', () {
  +            expect(value, new isInstanceOf<Vector4>());
  +          });
  +
  +          test('returns a vector with the correct values', () {
  +            expect(value.values, orderedCloseTo([1.1, 1.2, 1.3, 1.4], 0.00001));
  +          });
           });
         });
   
  
positive.code:           expect(() => attribute.extractFrom(table2[1]), throwsArgumentError);
          });
  
          test('with a valid row returns the correct value', () {
            expect(attribute.extractFrom(table[2]), equals(new Vector4(2.1, 2.2, 2.3, 2.4)));
          });
        });
  
  
negative.code:           expect(() => attribute.extractFrom(table2[1]), throwsArgumentError);
          });
  
          group('with a valid row', () {
            final value = attribute.extractFrom(table[2]);
  
            test('returns a Vector3 instance', () {
              expect(value, new isInstanceOf<Vector3>());
            });
  
            test('returns a vector with the correct values', () {
              expect(value.values, orderedCloseTo([2.1, 2.2, 2.3], 0.00001));
            });
          });
        });
  
  