C# using multi dim array as input for DataRow (MSTest)

Question

I'm currently building a Test Project and I need to pass several arguments to the test function. Because I need to call the test function with different parameter sets I decided to use ms-test with the [DataTestMethod]. Now I need to pass jagged arrays as Parameters to the function. But I don't get it to work. The call for TestMethod1 is working. The call for TestMethod2 is not working as it is not successfully compiling.

CS0182: An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type

using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTestProject2
{
    [TestClass]
    public class UnitTest1
    {

        [DataTestMethod]
        [DataRow(new int[] { })]
        public void TestMethod1(int[] values)
        {

        }

        [DataTestMethod]
        [DataRow(new int [][] { } )]
        public void TestMethod2(int[][] values)
        {
            
        }
    }
}

Does anyone has any suggestion to get this working? Sadly I need to use some kind of two dimension data type because I need to pass information about two loops inside of the test function. I can't use the params keyword because I need two of this jagged arrays in the test function.

Regards White

int[][] is not a multi-dimensional array but a jagged array. int[,] is a multi-dimensional array of rank 2 — Aluan Haddad
– Aluan Haddad, Commented Jan 14, 2021 at 17:05
thanks for the hint, I editet my question I really want to use a jagged array because not every "row" have the same amount of "columns" — White
– White, Commented Jan 14, 2021 at 17:23

Peska · Accepted Answer · 2021-01-14 18:22:03Z

You cannot use jagged array as a parameter in an attribute, because you cannot declare it as a const. More explanation in here: Const multi-dimensional array initialization

For your purpose I would use DynamicDataAttribute:

using Microsoft.VisualStudio.TestTools.UnitTesting;
using System.Collections.Generic;

namespace UnitTestProject
{
    [TestClass]
    public class TestClass
    {
        static IEnumerable<int[][][]> GetJaggedArray
        {
            get
            {
                return new List<int[][][]>
                {
                    new int[][][]
                    {
                        new int [][]
                        {
                            new int[] { 1 },
                            new int[] { 2, 3, 4 },
                            new int[] { 5, 6 }
                        }
                    }
                };
            }
        }

        [TestMethod]
        [DynamicData(nameof(GetJaggedArray))]
        public void Test1(int[][] jaggedArray)
        {
            Assert.AreEqual(1, jaggedArray[0][0]);
            Assert.AreEqual(2, jaggedArray[1][0]);
            Assert.AreEqual(3, jaggedArray[1][1]);
            Assert.AreEqual(4, jaggedArray[1][2]);
            Assert.AreEqual(5, jaggedArray[2][0]);
            Assert.AreEqual(6, jaggedArray[2][1]);
        }
    }
}

I know that syntax IEnumerable<int[][][]> is not pleasant for eyes, but since DynamicDataAttribute.GetData(MethodInfo) method is returning IEnumerable<object[]>, and your object is int[][], this is what you get.

Am I right, that in this case you need GetJaggedArray method for every Test1 call? It's not very compact code...

Jo T · Accepted Answer · 2023-09-27 17:53:01Z

0

The way to pass a jagged array in the DataRow attribute is to put it last in the data row's input list and use the 'params' for the last argument of your test method.
E.g. I added a new boolean input argument 'anotherTestInput' and passed the jagged array argument 'values' last and used the 'params' keyword:

        [DataTestMethod]
        [DataRow(true, new[] { 3,2 }, new[] { 4,3,5 }, new[] { 4 })]
        [DataRow(false, new[] { 8,2 }, new[] { 1,7,9 })] 
        public void TestMethod2(bool anotherTestInput, params int[][] values)
        {
            ...
        }

That way you can write only 1 test method and use different DataRow inputs to test (which is the purpose of DataRow[]).

edited Sep 27, 2023 at 17:53

answered Sep 27, 2023 at 17:50

Jo T

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