Object of type 'System.Int32' cannot be converted to type 'System.Int32[]'

Question

I have a method defined like this

public void test(string fileName, int totalObjects, params int[] objectsToTest)

I am trying to use it in my NUnit test class like this

[TestCase("test.doc", 1, 3)]
public void test(string fileName, int totalObjects, params int[] objectsToTest)

the code compiles just fine but when NUnit test runner tries to perform the test I get the following exception:

System.ArgumentException : Object of type 'System.Int32' cannot be converted to type 'System.Int32[]'.

How can I get rid of the error and keep the ability to use the TestCase syntax test for method parameters?

EDIT:

I know I can pass an array (and I don't need to declare last parameter with params keyword for this). I am trying to avoid explicit passing of the array.

possible duplicate of [Passing single value to params argument in NUnit TestCase](http://stackoverflow.com/questions/9550056/passing-single-value-to-params-argument-in-nunit-testcase) — DonBoitnott, Nov 25 '14 at 18:51
I've just made a project with the code provided by OP and the testCase works fine here. Using NUnit 2.6.3 — Anders, Nov 25 '14 at 19:01

score 1 · Answer 1 · answered Nov 25 '14 at 19:07

Just tried the following:

[TestFixture]
public class tester
{
    [TestCase("test.doc", 1, 3)]
    [TestCase("test.doc", 1, 3, 4, 5, 6)]
    public void test(string filename, int totalObjects, params int[] objectsToTest)
    {

    }
}

And both tests passed, and breakpoints show the objects are passed correctly.

Using NUnit 2.6.3 and .NET 4.5 and extension NUnit Test Adapter to run.

Aloraman · Accepted Answer · 2014-11-25T19:12:25.503

There is no problem with your method. Actual problem is in TestCaseAttribute from NUnit framework: it's just not smart enough to overcome runtime limitations.

In CLR runtime (and in compiled code) there is no "params", just corresponding array parameter. Information about existence of "params" is saved by defining ParamArrayAttribute instance on corresponding method. So, NUnit tries to apply supplied parameters as arguments to method, but it does not check if ParamArrayAttribute is defined on method and, therefore, does not wrap last argument to array. So you have to explicitly declare an array as parameter, not single value.

UPD: Based on comments supplied, I think that there is good chance this bug was fixed in recent NUnit release

score 0 · Answer 3 · answered Nov 25 '14 at 18:39

0

Did you try:

[TestCase("test.doc", 1, new int[] { 3 }]

answered Nov 25 '14 at 18:39

Ludovic Feltz

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Yes. And it works but I would like to use more cleaner syntax. – Bobrovsky Nov 25 '14 at 18:40
@Bobrovsky So what's the problem? i don't understand – Ludovic Feltz Nov 25 '14 at 18:41
I know I can pass an array (and I don't need to declare last parameter with `params` keyword for this). I am trying to avoid explicit passing of the array. – Bobrovsky Nov 25 '14 at 18:43
@Bobrovsky Ho i see ! So sorry i don't know how to do that – Ludovic Feltz Nov 25 '14 at 18:45
@Bobrovsky Maybe you can write a method `public void test(string fileName, int totalObjects, int objectsToTest)` who make the cast and call your method? – Ludovic Feltz Nov 25 '14 at 18:47

Object of type 'System.Int32' cannot be converted to type 'System.Int32[]'

3 Answers3