CODEWITHSUNDEEP
c#unit-testingnunit
JAFS6
JAFS6

Reputation: 45

Too many arguments provided using params keyword with NUNIT in C#

Hello I'm writing some unit tests for a WPF application using NUNIT framework and I'm facing this problem:

I write my positive test cases like that:

public static IEnumerable<TestCaseData> ThrowExceptionOnAnyStringNull_ShouldNotThrowException_TestCases
{
    get
    {
        yield return new TestCaseData(new string[] { "", "first test argument name" });
        yield return new TestCaseData(new string[] { "test string", "first test argument name" });
        yield return new TestCaseData(new string[] { "first", "first name", "second", "second name", "third", "third name" });
    }
}

And I'm using it like that:

[TestCaseSource(nameof(ThrowExceptionOnAnyStringNull_ShouldNotThrowException_TestCases))]
public void ThrowExceptionOnAnyStringNull_ShouldNotThrowException (params string[] args)
{
    Assert.DoesNotThrow(() => ArgumentChecker.ThrowExceptionOnAnyStringNull(args));
}

The signature of the method to test is:

public static void ThrowExceptionOnAnyStringNull (params string[] argsAndNames)

The error I receive from Visual Studio when I run the tests is: Too many arguments provided

I've tried to add a first parameter like I'm doing in other tests and its works! but the parameter remains unused.

This is the code used with that extra parameter:

public static IEnumerable<TestCaseData> ThrowExceptionOnAnyStringNull_ShouldNotThrowException_TestCases
{
    get
    {
        yield return new TestCaseData(null, new string[] { "", "first test argument name" });
        yield return new TestCaseData(null, new string[] { "test string", "first test argument name" });
        yield return new TestCaseData(null, new string[] { "first", "first name", "second", "second name", "third", "third name" });
    }
}

[TestCaseSource(nameof(ThrowExceptionOnAnyStringNull_ShouldNotThrowException_TestCases))]
public void ThrowExceptionOnAnyStringNull_ShouldNotThrowException (Type expectedExceptionType, params string[] args)
{
    Assert.DoesNotThrow(() => ArgumentChecker.ThrowExceptionOnAnyStringNull(args));
}

I have other 53 tests with this structure of TestCaseSource currently working perfect.

How can I get rid of that extra parameter to get a clean code?

Thank you.

Extra info:

This is how my negative test cases look like:

public static IEnumerable<TestCaseData> ThrowExceptionOnAnyStringNull_ShouldThrowException_TestCases
{
    get
    {
        // Empty list
        yield return new TestCaseData(typeof(ArgumentNullException), null);
        // List with odd number of elements
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { null });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "" });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "test string" });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { null, "first test argument name", null });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "", "first test argument name", "" });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "test string", "first test argument name", "other" });
        // List with even number of elements
        yield return new TestCaseData(typeof(ArgumentNullException), new string[] { null, null });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { null, "" });
        yield return new TestCaseData(typeof(ArgumentNullException), new string[] { null, "first test argument name" });
        yield return new TestCaseData(typeof(ArgumentNullException), new string[] { "", null });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "", "" });
        yield return new TestCaseData(typeof(ArgumentNullException), new string[] { "test string", null });
        yield return new TestCaseData(typeof(ArgumentException)    , new string[] { "test string", "" });
        yield return new TestCaseData(typeof(ArgumentNullException), new string[] { "first", "first name", null, "second name", "third", "third name" });
    }
}

[TestCaseSource(nameof(ThrowExceptionOnAnyStringNull_ShouldThrowException_TestCases))]
public void ThrowExceptionOnAnyStringNull_ShouldThrowException (Type expectedExceptionType, params string[] args)
{
    Assert.Throws(expectedExceptionType, () => ArgumentChecker.ThrowExceptionOnAnyStringNull(args));
}

Upvotes: 1

Views: 627

Answers (1)

weichch
weichch

Reputation: 10035

Try:

yield return new TestCaseData(new object[] { new string[] { <string array elements> }})

The issue was object[] is assignable from string[], so your string[] was parsed as each element being one separate parameter not the whole being one single parameter.

Upvotes: 3

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