public void DelegatingStream_EndWrite() { // Arrange Mock<Stream> mockInnerStream = new Mock<Stream>(); MockDelegatingStream mockStream = new MockDelegatingStream(mockInnerStream.Object); Mock<IAsyncResult> mockIAsyncResult = new Mock<IAsyncResult>(); // Act mockStream.EndWrite(mockIAsyncResult.Object); // Assert mockInnerStream.Verify(s => s.EndWrite(mockIAsyncResult.Object), Times.Once()); }