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c#unit-testingstreamwriter
Yogurt The Wise
Yogurt The Wise

Reputation: 4499

C# Unit Test a StreamWriter parameter

I have a bunch of classes that all implement an Interface and one of the parameters is a StreamWriter.

I need to check the contents of the StreamWriter.

I am trying to find a way to avoid writing text files on the test server and opening them to check the contents.

Is there is a way to quickly convert the StreamWriter contents/stream to a StringBuilder variable?

Upvotes: 13

Views: 10267

Answers (3)

Darin Dimitrov
Darin Dimitrov

Reputation: 1039248

You cannot check the StreamWriter. You could check the underlying stream it is writing to. So you could use a MemoryStream in your unit test and point this StreamWriter to it. Once it has finished writing you could read from it.

[TestMethod]
public void SomeMethod_Should_Write_Some_Expected_Output()
{
    // arrange
    using (var stream = new MemoryStream())
    using (var writer = new StreamWriter(stream))
    {
        // act
        sut.SomeMethod(writer);

        // assert
        string actual = Encoding.UTF8.GetString(stream.ToArray());
        Assert.AreEqual("some expected output", actual);
    }
}

Upvotes: 23

Priyank Thakkar
Priyank Thakkar

Reputation: 4852

In that case you need to mock the test case. You can use frameworks likes rhino mocks. That advantage of mocking framework is, you can verify the contents of the objects, but you don't have to hit server or occupy server resources.

This link will provide you the basic examples: http://www.codeproject.com/Articles/10719/Introducing-Rhino-Mocks

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1502546

I would suggest you change the parameter to TextWriter if at all possible - at which point you can use a StringWriter.

Alternatively, you could create a StreamWriter around a MemoryStream, then test the contents of that MemoryStream later (either by rewinding it, or just calling ToArray() to get the complete contents as a byte array. If you really want to be testing text though, it's definitely simpler to use a StringWriter.

Upvotes: 13

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