CODEWITHSUNDEEP
c#unit-testingnunitresharper
Matt W
Matt W

Reputation: 12423

NUnit 2016 Throws.TypeOf

Why does this code throw an exception instead of passing the test?

public static int ThrowsSomething(string name)
{
    if (name == null)
        throw new ArgumentNullException(nameof(name), "can't be null because that's silly");
    return -1;
}

[Test]
public void WindowTest()
{
    Assert.That(ThrowsSomething("dave"), Is.EqualTo(-1));
    Assert.That(ThrowsSomething(null), Throws.TypeOf<ArgumentNullException>());
}

Unit Test Sessions window shows this:

WindowTest [0:00.066] Failed: System.ArgumentNullException : can't be null because that's silly

Visual Studio 2015 with ReSharper Ultimate 2016.3 and NUnit 3.6.1

Upvotes: 4

Views: 527

Answers (1)

Nkosi
Nkosi

Reputation: 247173

Test fails because the thrown exception is uncaught and prevents the test from exercising to completion.

Use Assert.Throws<> to assert the thrown exception

[Test]
public void WindowTest() {
    Assert.That(ThrowsSomething("dave"), Is.EqualTo(-1));
    Assert.Throws<ArgumentNullException>(() => ThrowsSomething(null));
}

or use a delegate so that the exception can be caught and handled by the assertion.

Assert.That(() => ThrowsSomething(null), Throws.Exception.TypeOf<ArgumentNullException>());

Upvotes: 6

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