NUnit cannot recognise a TestCase when it contains an array

Question

This is quite simple but annoying behaviour I am running into with NUnit:

I have some tests like this:

[Test]
[TestCase( 1, 2, "hello" )]
[TestCase( 3, 5, "goodbye" )]
public void MyClass_MyMethod( int a, int b, string c )
{
    Assert.IsTrue( a < b );
}

This works fine and in the ReSharper NUnit pane I can see each TestCase getting its own response in the result.

I have a second TestCase that looks like this:

[Test]
[TestCase( 1, 2, new long[] { 100, 200 })]
[TestCase( 5, 3, new long[] { 300, 500 })]
public void MyClass_MyOtherMethod( long a, long b, long[] bunchOfNumbers )
{
   Assert.IsTrue( a < b );
}

When I run it I see this:

One or more child tests had errors Exception doesn't have a stacktrace

public void MyClass_MyOtherMethod(5,3,System.Int64[]) failed

The difference being that with my other tests it draws out each TestCase as a separate checkbox on the test list, whereas this one does not get shown and I have no detail until I run it in a debugger as to what went wrong and where. I am a little concerned about how this test will behave on the build machine. Does anyone have any idea what is going on and why?

Could also be the ReSharper test runner that doesn't support it. — Torbjörn Kalin, Jul 29 '13 at 13:59
What versions of NUnit and Resharper do you use? I remember that some problems were fixed in more late versions of one of them. — Mikhail Brinchuk, Jul 30 '13 at 13:29
By the way, have not you tried to pass this array marked with `params` modifier? — Mikhail Brinchuk, Jul 30 '13 at 13:31
NUnit 2.6.2 against ReSharper 7.1 - probably I need to raise this with Jetbrains. What does the params modifier do? — glenatron, Jul 30 '13 at 14:15

score 36 · Accepted Answer · answered Jul 30 '13 at 14:24

36

Following on from this bug at JetBrains it looks as though the solution here is to use the TestName attribute on your different cases:

[Test]
[TestCase( 1, 2, new long[] { 100, 200 }, TestName="Test 1" )]
[TestCase( 5, 3, new long[] { 300, 500 }, TestName="Test 2" )]
public void MyClass_MyOtherMethod( long a, long b, long[] bunchOfNumbers )
{
   Assert.IsTrue( a < b );
}

Everything now shows correctly in ReSharper if one of my tests fails.

answered Jul 30 '13 at 14:24

glenatron

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3

It looks like with current versions of NUnit and ReSharper this workaround is no longer required. – arni Oct 30 '14 at 17:08
4

It still doesn't like it if your first parameter is the array. – Jacob Brewer Mar 03 '15 at 15:29
But it works if you have more than one array in the parameter list. – vgaltes Jan 05 '16 at 20:56
4

@JacobBrewer: That's because the signature of `TestCase` expect `params object[]` as its first parameter - so passing in an array will lead to nUnit looking for a test method signature where the parameters match the type and length of the array. – Oliver Mar 30 '17 at 16:13

Ray · Answer 2 · 2019-09-27T17:32:30.890

16

For an array that contains strings, use an object array with the TestCase attributes along with params:

[Test]
[TestCase(new object[] {"foo", "bar", "baz"})]
[TestCase(new object[] {"300", "500", "700"})]    
public void MyClass_SomeOtherMethod(params string[] bunchOfStrings)
{
    // assert something...
}

edited Sep 27 '19 at 17:32

answered Oct 05 '17 at 22:37

Ray

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This didn't quite work for me, using MSTest with NUnit adapter. Error message was `Too many arguments provided, provide at most 1 arguments.` and this must have been at test runner level as I couldn't even step into the test. Adding `params` keyword in the test method signature did the trick. – user1007074 Nov 22 '18 at 17:48
Thanks @user1007074. Updated the answer with your fix. – Ray Sep 27 '19 at 17:34
For Rider 2020.3.2, this is the way for a unit test with a single array parameter. – rgvlee Feb 11 '21 at 09:06
This doesn't work for .Net 6.0 projects, and/or whatever version of NUnit I'm using. It throws an error: Object of type 'System.Object[]' cannot be converted to type 'System.String[]'. Instead of "new object[]", you have to declare it as a string, or just minimize it with "new[]". – computercarguy Mar 07 '23 at 22:53

score 4 · Answer 3 · answered May 21 '16 at 15:19

An alternative is to use a string for the array:

[TestCase( 1, 2, "100, 200")]
[TestCase( 5, 3, "300, 500")]
public void MyClass_MyOtherMethod(long a, long b, string bunchOfNumbersString)
{
    var bunchOfNumbers= bunchOfNumbersString.Split(',')
                                            .Select(long.Parse)
                                            .ToArray();
   ...
}

The upside with this approach is that it will render nicly in the testrunner.

Side note: The [Test] is not needed when using [TestCase] or at least I don't see that it solves a problem.

score 2 · Answer 4 · answered Mar 16 '21 at 09:15

2

I came across an issue with this where the order of the arguments mattered. Using Rider 2020.1.4

[TestCase(new string[] { "ABC", "DEF" }, false)]
public void SomeTestWithParams(string[] stringArr, bool someBool) {}

Gave me an error, but

[TestCase(false, new string[] { "ABC", "DEF" })]
public void SomeTestWithParams(bool someBool, string[] stringArr) {}

worked just fine

answered Mar 16 '21 at 09:15

ste-fu

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second one works because in the TestCase function, you can not directly pass array. Either you pass the first arguemnt as int/string/bool and second argument is array is allowed Or you use the 'new object [] inside the testCase function then you are allowed to pass the array directly' – Ankush Feb 22 '22 at 08:57

score 1 · Answer 5 · answered Feb 12 '19 at 22:08

1

This works in VS 2017 with NUnit 3.11.0

[TestCase(new long[] {5, 6, 942135153})]
public void DummyTest(long[] values)
{
    Assert.That(values != null);
}

answered Feb 12 '19 at 22:08

Matt

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3

NUnit cannot recognise a TestCase when it contains an array

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