枚举Mocked Indexer属性会导致集合变空 [英] Enumerating a Mocked Indexer Property Causes the Collection to Become Empty
问题描述
好的，要重现，这就是你需要的东西
Okay, to reproduce, here is what you need
public interface IWorkbookSet
{
IWorkbooks Workbooks { get; }
}
public interface IWorkbooks : IEnumerable
{
IWorkbook this[int index] { get; }
IWorkbook this[string name] { get; }
int Count { get; }
}
public interface IWorkbook
{
IWorksheets Worksheets { get; }
}
public interface IWorksheets : IEnumerable
{
IWorksheet this[int index] { get; }
IWorksheet this[string name] { get; }
int Count { get; }
IWorksheet Add();
IWorksheet AddAfter(IWorksheet sheet);
IWorksheet AddBefore(IWorksheet sheet);
bool Contains(IWorksheet worksheet);
}
public interface IWorksheet
{
string Name { get; set; }
}
使用以下代码设置Microsoft单元测试
Set up a Microsoft unit test using the following code
[TestInitialize]
public void Initialize()
{
List<string> fakeSheetNames = new List<string>()
{
"Master", "A", "B", "C", "__ParentA", "D", "wsgParentB", "E", "F", "__ParentC", "__ParentD", "G"
};
// Worksheets.
var fakeWorksheetsList = new List<IWorksheet>();
foreach (string name in fakeSheetNames)
{
var tmpMock = new Mock<IWorksheet>();
tmpMock.Setup(p => p.Name).Returns(name);
tmpMock.Setup(p => p.Visible)
.Returns(parentPrefixes.Any(p => name.StartsWith(p)) ?
SheetVisibility.Hidden :
SheetVisibility.Visible);
fakeWorksheetsList.Add(tmpMock.Object);
}
var mockWorksheets = new Mock<IWorksheets>();
mockWorksheets.Setup(m => m[It.IsAny<int>()]).Returns<int>(index => fakeWorksheetsList[index]);
mockWorksheets.Setup(m => m.GetEnumerator()).Returns(fakeWorksheetsList.GetEnumerator());
mockWorksheets.SetupGet(m => m.Count).Returns(fakeWorksheetsList.Count);
// Workbook.
var mockWorkbook = new Mock<IWorkbook>();
mockWorkbook.Setup(p => p.Name).Returns("Name");
mockWorkbook.Setup(p => p.FullName).Returns("FullName");
mockWorkbook.Setup(p => p.Worksheets).Returns(mockWorksheets.Object);
// Workbooks.
var fakeWorkbooksList = new List<IWorkbook>() { mockWorkbook.Object };
var mockWorkbooks = new Mock<IWorkbooks>();
mockWorkbooks.Setup(m => m[It.IsAny<int>()]).Returns<int>(index => fakeWorkbooksList[index]);
mockWorkbooks.Setup(m => m.GetEnumerator()).Returns(fakeWorkbooksList.GetEnumerator());
mockWorkbooks.SetupGet(m => m.Count).Returns(fakeWorkbooksList.Count);
// WorkbookSet.
mockWorkbookSet = new Mock<IWorkbookSet>();
mockWorkbookSet.Setup(m => m.Workbooks).Returns(mockWorkbooks.Object);
var expectedWorkBooksIndex = 0;
var expectedWorkSheetIndex = 1;
var expected = fakeWorksheetsList[expectedWorkSheetIndex];
// Setup test.
var workbookSet = mockWorkbookSet.Object;
var actual = workbookSet
.Workbooks[expectedWorkBooksIndex]
.Worksheets[expectedWorkSheetIndex];
Assert.AreEqual(expected, actual);
Assert.AreEqual(12, workbookSet.Workbooks[0].Worksheets.Count);
}
现在在测试方法中，这样做
Now in a test method, do this
[TestMethod]
public async Task StrucutreGenerationAsyncTest()
{
foreach (IWorksheet ws in mockWorkbookSet.Object.Workbooks[0].Worksheets)
Trace.WriteLine("1111 ws = " + ws.Name);
foreach (IWorksheet ws in mockWorkbookSet.Object.Workbooks[0].Worksheets)
Trace.WriteLine("2222 ws = " + ws.Name);
}
输出：
Test Name: StrucutreGenerationAsyncTest
Test Outcome: Passed
Result StandardOutput:
Debug Trace:
1111 ws = Master
1111 ws = A
1111 ws = B
1111 ws = C
1111 ws = __ParentA
1111 ws = D
1111 ws = wsgParentB
1111 ws = E
1111 ws = F
1111 ws = __ParentC
1111 ws = __ParentD
1111 ws = G
第一个 foreach 枚举 IWorksheets ，第二个不（？）as mockWorkbookSet.Object.Workbooks [0] .Worksheets 现在为空。
The first foreach enumerate the IWorksheets, the second does not(?) as mockWorkbookSet.Object.Workbooks[0].Worksheets is now empty.
更奇怪的是这个
[TestMethod]
public async Task StrucutreGenerationAsyncTest()
{
if (mockWorkbookSet.Object.Workbooks[0].Worksheets
.Cast<IWorksheet>().Any(ws => ws.Name.Compare("Master")))
Trace.WriteLine("Match!");
foreach (IWorksheet ws in mockWorkbookSet.Object.Workbooks[0].Worksheets)
Trace.WriteLine("1111 ws = " + ws.Name);
foreach (IWorksheet ws in mockWorkbookSet.Object.Workbooks[0].Worksheets)
Trace.WriteLine("2222 ws = " + ws.Name);
}
输出：
Test Name: StrucutreGenerationAsyncTest
Test Outcome: Passed
Result StandardOutput:
Debug Trace:
Match!
1111 ws = A
1111 ws = B
1111 ws = C
1111 ws = __ParentA
1111 ws = D
1111 ws = wsgParentB
1111 ws = E
1111 ws = F
1111 ws = __ParentC
1111 ws = __ParentD
1111 ws = G
大师去了哪里？这就像枚举的行为从集合中删除项目。为什么会发生这种情况，我该如何解决？
Where has "Master" gone? It is like the act of enumerating removes items from the collection. Why is this happening and how can I fix it?
编辑＃1 ：我尝试使用方法模拟枚举器，如下所示
Edit #1: I have tried mocking the enumerator using a method, as follows
var mockWorksheets = new Mock<IWorksheets>();
mockWorksheets.Setup(m => m[It.IsAny<int>()]).Returns<int>(index => fakeWorksheetsList[index]);
mockWorksheets.Setup(m => m.GetEnumerator()).Returns(fakeWorksheetsList.GetEnumerator());
mockWorksheets.SetupGet(m => m.Count).Returns(fakeWorksheetsList.Count);
使用
private IEnumerator<IWorksheet> WorksheetList()
{
foreach (string name in fakeSheetNames)
{
var mock = new Mock<IWorksheet>();
mock.Setup(p => p.Name).Returns(name);
mock.Setup(p => p.Visible)
.Returns(parentPrefixes.Any(p => name.StartsWith(p)) ?
SheetVisibility.Hidden :
SheetVisibility.Visible);
yield return mock.Object;
}
}
这没有帮助。
推荐答案
mockWorksheets.Setup(m => m.GetEnumerator()).Returns(fakeWorksheetsList.GetEnumerator());
每次返回相同的枚举器实例，当使用一次时需要重置（导致外观）任何后续枚举的空集合。）
returns the same enumerator instance every time which when used once will need to be reset (resulting in the appearance of an empty collection on any subsequent enumeration).
如果你想在每次调用时都有一个新的枚举器，那么你需要传递返回一个lambda表达式：
If you want a new enumerator on every call, then you need to pass Returns a lambda expression:
mockWorkSheets.Setup(m => m.GetEnumerator()).Returns(() => fakeWorksheetsList.GetEnumerator());
每次 GetEnumerator（）被叫。因此，现在多次枚举模拟应该按预期工作。
The lambda will get called every time GetEnumerator() is called. So now enumerating the mock multiple times should then work as expected.
参考 Moq First（）Last（）和GetEnumerator（）wierdness
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