NUnit + Moq抛出异常

Question

下面是测试中的代码。 view.QueryResultsGrid是System.Windows.Forms.DataGridView对象：正在尝试

public void SelectCheckedChanged(object sender, EventArgs e) 
{ 
    view.QueryResultsGrid.SelectionMode = DataGridViewSelectionMode.ColumnHeaderSelect; 
} 

测试：

private Mock<IQueryForm> mockWindow; 
private QueryFormPresenter presenter; 

/// <summary> 
/// Runs ONCE prior to any tests running 
/// </summary> 
[TestFixtureSetUp] 
public void TestFixtureSetUp() 
{ 
    //We're interested in testing the QueryFormPresenter class here, but we 
    //don't really care about the QueryForm window (view) since there is hardly any code in it. 
    //Therefore, we create a mock of the QueryForm view, and pass it to the QueryFormPresenter to use. 
    mockWindow = new Mock<IQueryForm>(); 
    presenter = new QueryFormPresenter(mockWindow.Object); 
} 


[Test] 
public void Moq_Is_Hard() 
{ 
    //Arrage 
    DataGridView d = new DataGridView(); 
    mockWindow.SetupGet(x => x.QueryResultsGrid).Returns(d); 

    //Act 
    presenter.SelectCheckedChanged(null, null); 

    //Assert 
    //mockView.VerifyGet(x => x.QueryResultsGrid.SelectionMode, Times.AtMostOnce()); 
    mockWindow.VerifySet(x => x.QueryResultsGrid.SelectionMode, Times.AtMostOnce()); 
} 

如果我把一个断点的测试代码行，VS告诉我：在属性或索引器'Presenter.IQueryForm.QueryResults'不能在此上下文中使用，因为它缺少get访问器。然而，在测试中，我以为我在模拟上设置了Get访问器，所以我不理解那个消息。最后，NUnit给出：'未设置对象实例的对象引用'异常。

任何帮助，非常感谢！

安迪

Answer 1

那么你的代码做的是充分利用模拟DataGridView的，然后设置就可以了SelectionMode属性。 DataGridView的实际实现不在Mocks控件下，因此它无法拦截SelectionMode的getter和setter。

其中一个问题（您可能已经发现）是DataGridView并不是真正的Mockable，因此您必须返回实际的实现，将任何属性都删除，然后完成相关任务。

下测试通过我...

[Test] 
public void SelectCheckedChanged_SetsModeToColumnHeaderSelect() { 
    //Arrange 
    //Mock the form to return a stubbed grid 
    Mock<IQueryForm> form = new Mock<IQueryForm>(); 
    DataGridView grid = new DataGridView(); 
    grid.SelectionMode = DataGridViewSelectionMode.CellSelect; 
    form.SetupGet(f => f.QueryResults).Returns(grid); 
    QueryFormPresenter presenter = new QueryFormPresenter(form.Object); 

    //Act 
    presenter.SelectCheckedChanged(); 

    //Assert 
    form.VerifyGet(f => f.QueryResults); 
    Assert.AreEqual(DataGridViewSelectionMode.ColumnHeaderSelect, 
        grid.SelectionMode); 
}