如何使用 NSubstitute 模拟 Outlook.MailItem 与多个附件？

Question

我正在尝试对接受 Outlook.MailItem 参数类型的静态函数进行单元测试：

public static bool GetMailAndDoSomething(Outlook.MailItem mailitem)

这是我目前的测试函数：

using Outlook = Microsoft.Office.Interop.Outlook;
...
public void TestGetMailAndDoSomething()
{
    Outlook.MailItem mailItem = Substitute.For<Outlook.MailItem>();

    Outlook.Attachments attachments = Substitute.For<Outlook.Attachments>();
    attachments.Add(Substitute.For<Outlook.Attachment>());
    attachments.Add(Substitute.For<Outlook.Attachment>());
    attachments.Add(Substitute.For<Outlook.Attachment>());
    attachments.Add(Substitute.For<Outlook.Attachment>());

    mailItem.Attachments.GetEnumerator().Returns(attachments.GetEnumerator());

    Assert.True(Misc.GetMailAndDoSomething(mailItem));
}

在GetMailAndDoSomething函数里面，有一段代码我要测试

foreach (Outlook.Attachment attachment in mailItem.Attachments)
{
       //do someting
}

但是，测试程序永远不会到达 //do something，因为 mailItem.Attachments 似乎总是空的。这是我在 IDE 在 foreach 行中断时看到的。

我需要在测试函数中修复什么，以便测试程序在目标函数中达到 //do something？

Answer 1

您正在尝试在接口上执行实现。

Attachments 派生自 IEnumerable

[System.Runtime.InteropServices.Guid("0006303C-0000-0000-C000-000000000046")]
public interface Attachments : System.Collections.IEnumerable

考虑使用实际列表作为内存存储，然后将模拟设置为 return

var list = new List<Outlook.Attachment>();
list.Add(Substitute.For<Outlook.Attachment>());
list.Add(Substitute.For<Outlook.Attachment>());
list.Add(Substitute.For<Outlook.Attachment>());
list.Add(Substitute.For<Outlook.Attachment>());

Outlook.Attachments attachments = Substitute.For<Outlook.Attachments>();
attachments.GetEnumerator().Returns(list.GetEnumerator());

Outlook.MailItem mailItem = Substitute.For<Outlook.MailItem>();
mailItem.Attachments.Returns(attachments);

//...

如何使用 NSubstitute 模拟 Outlook.MailItem 与多个附件？

How do I mock Outlook.MailItem with multiple Attachments using NSubstitute?

c#

outlook

unit-testing

nsubstitute