TDD: Function with a list return good values but it's not working

Question

I started C# recently and i have to do a project called Ray tracer challenge. For that, we need to first do some Test driven dev, then it's coding time. The problem i got is: The result that needs to be check is returned with <> instead of () and so the test, even if the values are ok, can't pass.

This is my TDD code:

[Test]
public void Adding()
{
    var a = new List<double>() { 3.5, -2.0, 5.0, 1.0 }; // point
    var b = new List<double>() { -2.0,  3.0, 1.0,  0.0 }; // point

    Assert.AreEqual((a[0] + b[0], a[1] + b[1], a[2] + b[2], a[3] + b[3]), Addition.Add(string.Empty));
}

This is my return function:

internal static List<double> Add(string numbers)
{
    return new List<double> { 1.5, 1.0, 6.0, 1.0 };
}

The result is

Adding
   Source: UnitTest1.cs line 11
   Duration: 158 ms

  Message: 
      Expected: (1.5d, 1.0d, 6.0d, 1.0d)
      But was:  < 1.5d, 1.0d, 6.0d, 1.0d >
    
  Stack Trace: 
    Tests.Adding() line 17

I can't change

Assert.AreEqual((a[0] + b[0], a[1] + b[1], a[2] + b[2], a[3] + b[3]), Addition.Add(string.Empty));

Could someone explain me please? PS: I know that testing an addition isn't really worth it, i'm mostly training on basic things.

Answer 1

Your assert compares this: (a[0] +... + b[3]) which is a tuple, and this: new List<double>() { 3.5,... 1.0 } which is a list.

Since they're different collection types, the comparison does not work as expected.

Either use a List as your assert expected value:

Assert.AreEqual(new List<double> { a[0] + ... + b[3]}, Addition.Add(string.Empty));

Or change your return function to return a Tuple like so:

{
    return (1.5, 1.0, 6.0, 1.0);
}