比較兩個列表 <object> 返回不同的結果

Question

我有一個叫做TestResult的類，它看起來像這樣：

 public class TestResult : IEquatable<TestResult> {

        public TestResult(string labelName, List<object> correctValues) {
            this.LabelName = labelName;
            this.SelectedValues = correctValues;
        }

        public TestResult() {
        }

        public string LabelName { get; set; }
        public List<object> SelectedValues { get; set; }

        public override bool Equals(object obj) {
            if (ReferenceEquals(null, obj)) {
                return false;
            }
            if (ReferenceEquals(this, obj)) {
                return true;
            }

            return obj.GetType() == GetType() && Equals((TestResult)obj);
        }

        public override int GetHashCode() {
            unchecked {
                int hashCode = this.LabelName.GetHashCode();
                hashCode = (hashCode * 397) ^ this.SelectedValues.GetHashCode();
                return hashCode;
            }
        }

        public bool Equals(TestResult other) {
            if (ReferenceEquals(null, other)) {
                return false;
            }
            if (ReferenceEquals(this, other)) {
                return true;
            }

            bool areEqual = false;

            if (this.LabelName == other.LabelName) {
                areEqual = true;
            }

            if (this.SelectedValues?.Count != other.SelectedValues?.Count) {
                return false;
            }

            areEqual = this.SelectedValues.OrderBy(x => x).SequenceEqual(other.SelectedValues.OrderBy(x => x));

            return areEqual;
        }

        /// <summary>
        /// Override ==(you must ovverride this so if a developer called == it will return the same result as if they called Equals
        /// </summary>
        /// <param name="obj1"></param>
        /// <param name="obj2"></param>
        /// <returns></returns>
        public static bool operator ==(TestResult obj1, TestResult obj2) {
            if (ReferenceEquals(obj1, obj2)) {
                return true;
            }

            if (ReferenceEquals(obj1, null)) {
                return false;
            }
            if (ReferenceEquals(obj2, null)) {
                return false;
            }

            bool areEqual = false;

            if (obj1.LabelName == obj2.LabelName) {
                areEqual = true;
            }

            if (obj1.SelectedValues?.Count != obj2.SelectedValues?.Count) {
                return false;
            }

            areEqual = obj1.SelectedValues.OrderBy(x => x).SequenceEqual(obj2.SelectedValues.OrderBy(x => x));

            return areEqual;
        }

        /// <summary>
        /// No need to repeat myself, just return the opposite of the == function
        /// </summary>
        /// <param name="obj1"></param>
        /// <param name="obj2"></param>
        /// <returns></returns>
        public static bool operator !=(TestResult obj1, TestResult obj2) {
            return !(obj1 == obj2);
        }

如您所見，我重寫了equals方法，以便在創建列表時可以比較對象。

然后，我有一個單元測試，該單元測試了我的equals方法，它看起來像這樣：

   [TestMethod]
        public void ReturnIncorrectTestResults_IncorrectValuesSubmitted_3LabelsWillBeReturned() {
            List<string> failedLabelNames;

            var submittedResults = new List<Repository.TestManagement.Models.TestResult> {
                new Repository.TestManagement.Models.TestResult("Question1Label", new List<object> { true }),
                new Repository.TestManagement.Models.TestResult("Question2Label", new List<object> { true }), //Difference
                new Repository.TestManagement.Models.TestResult("Question3Label", new List<object> { 3, 4 }),
                new Repository.TestManagement.Models.TestResult("Question4Label", new List<object> { true }),
                new Repository.TestManagement.Models.TestResult("Question5Label", new List<object> { 1, 3 }), //Difference
                new Repository.TestManagement.Models.TestResult("Question6Label", new List<object> { 1, 2, 3, 4 }),
                new Repository.TestManagement.Models.TestResult("Question7Label", new List<object> { 1, 2, 3 }),
                new Repository.TestManagement.Models.TestResult("Question8Label", new List<object> { 2 }),
                new Repository.TestManagement.Models.TestResult("Question9Label", new List<object> { 3 }), //Difference
                new Repository.TestManagement.Models.TestResult("Question10Label", new List<object> { 1, 2, 3, 4, 5 })
            };

            var validResults = new List<Repository.TestManagement.Models.TestResult> {
                new Repository.TestManagement.Models.TestResult("Question1Label", new List<object> { false }),
                new Repository.TestManagement.Models.TestResult("Question2Label", new List<object> { true }),
                new Repository.TestManagement.Models.TestResult("Question3Label", new List<object> { 3, 4 }),
                new Repository.TestManagement.Models.TestResult("Question4Label", new List<object> { true }),
                new Repository.TestManagement.Models.TestResult("Question5Label", new List<object> { 5,6 }),
                new Repository.TestManagement.Models.TestResult("Question6Label", new List<object> { 1, 2, 3, 4 }),
                new Repository.TestManagement.Models.TestResult("Question7Label", new List<object> { 1, 2, 3 }),
                new Repository.TestManagement.Models.TestResult("Question8Label", new List<object> { 2 }),
                new Repository.TestManagement.Models.TestResult("Question9Label", new List<object> { 1 }),
                new Repository.TestManagement.Models.TestResult("Question10Label", new List<object> { 1, 2, 3, 4, 5 })
            };

            failedLabelNames = _iTestManager.ReturnIncorrectTestLabels(submittedResults, validResults);

            Assert.IsTrue(failedLabelNames.Count == 3);
        }

因此，我的應用程序代碼中也有一個方法調用相同的equals函數：

  public List<string> ReturnIncorrectTestLabels(List<TestResult> submittedResults, List<TestResult> acceptedResults) {
            if (submittedResults.Count != acceptedResults.Count)
                throw new ArgumentException($"The submitted results count is {submittedResults.Count} and the accepted results count is {acceptedResults.Count}. Amount of results must be equal.");

            /*Compare the valid results against the submitted results. We join on the label names and 
        compare the results. Please not that this works because I have overridden the equals in 
        the TestResult class*/

            var failedResultLabelNames = (from accepted in acceptedResults
                                          join submitted in submittedResults
                         on accepted.LabelName equals submitted.LabelName
                                          where accepted != submitted
                                          select accepted?.LabelName).ToList();

            return failedResultLabelNames;

        }

我用它來比較兩個結果列表並返回任何失敗的值。

奇怪的是，我的單元測試通過了，但是當我在站點中進行測試時，它返回false，並且對象不相等。

因此，例如，如果我提交兩個看起來像這樣的列表：

var list1 = new List<TestResult> {
                new TestResult("Question1Label", new List<object> { 1,2,3 }),
                new TestResult("Question2Label", new List<object> { 4,5,6 })
            };

            var list2 = new List<TestResult> {
                new TestResult("Question1Label", new List<object> { "1","2","3" }),
                new TestResult("Question2Label", new List<object> { "4","5","6" })
            };

我為我的兩個列表調用ReturnIncorrectTestLabels方法，它將兩個列表項都返回為“失敗”。

為什么會這樣呢？

Answer 1

   public static bool operator ==(TestResult obj1, TestResult obj2) {
            if (ReferenceEquals(obj1, obj2)) {
                return true;
            }

            if (ReferenceEquals(obj1, null)) {
                return false;
            }
            if (ReferenceEquals(obj2, null)) {
                return false;
            }

            bool areEqual = false;

            if (obj1.LabelName == obj2.LabelName) {
                areEqual = true;
            }

            if (obj1.SelectedValues?.Count != obj2.SelectedValues?.Count) {
                return false;
            }

            //Order to make sure that they are in correct order to be compared
            obj1.SelectedValues = obj1.SelectedValues.OrderBy(x => x).ToList();
            obj2.SelectedValues = obj2.SelectedValues.OrderBy(x => x).ToList();

            for (int i = 0; i < obj1.SelectedValues.Count; i++) {
                var type = obj1.SelectedValues[i].GetType();
                //Use a dynamic so I can cast to the correct types at run time and compare
                dynamic castedObj1Val = Convert.ChangeType(obj1.SelectedValues[i], type);
                dynamic castedObj2Val = Convert.ChangeType(obj2.SelectedValues[i], type);
                if (castedObj1Val != castedObj2Val)
                    return false;
            }

            return areEqual;
        }

我在比較兩種不同的類型，因此在比較之前必須將它們轉換為正確的類型

Answer 2

這是因為!=的執行方式類似於交叉聯接，因此將所有內容與所有內容進行比較，因此，將第一個項目與第二個項目進行比較時，您將獲得failedResult；而將第二個項目與第一項進行比較時，您還將獲得一個failedResult。

這是因為你在加入LabelName是在兩個項目同list1和list2 。 嘗試比較標簽名稱何時唯一（如它們在單元測試中一樣），它應該給出預期的結果。

        var list1 = new List<TestResult> {
            new TestResult("1", new List<object> { 1,2,3 }),
            new TestResult("2", new List<object> { 4,5,6 })
        };

        var list2 = new List<TestResult> {
            new TestResult("1", new List<object> { 1,2,3 }),
            new TestResult("2", new List<object> { 4,5,6 })
        };

        var test = ReturnIncorrectTestLabels(list1, list2);