c#unit-testing extension-methods mstest assert

Unit test project is not finding extension methods

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

namespace PdbLib
{
    public static class AssertExtensions
    {
        public static void AssertVec3Equal(this Assert assert, Vec3 expected, Vec3 actual, double tolerance, string message = "")
        {
            Assert.IsTrue(expected.DistanceTo(actual) <= tolerance, message);
        }

        public static void AssertVec3NotEqual(this Assert assert, Vec3 expected, Vec3 actual, double tolerance, string message = "")
        {
            Assert.IsTrue(expected.DistanceTo(actual) > tolerance, message);
        }

        public static void AssertVec3Equal2(this Assert assert, Vec3 expected, Vec3 actual, double tolerance, string message = "")
        {
            if (Math.Abs(expected.X - actual.X) >= tolerance)
            {
                throw new AssertFailedException($"{message} X-component is incorrect. Expected: {expected.X}, Actual: {actual.X}");
            }

            if (Math.Abs(expected.Y - actual.Y) >= tolerance)
            {
                throw new AssertFailedException($"{message} Y-component is incorrect. Expected: {expected.Y}, Actual: {actual.Y}");
            }

            if (Math.Abs(expected.Z - actual.Z) >= tolerance)
            {
                throw new AssertFailedException($"{message} Z-component is incorrect. Expected: {expected.Z}, Actual: {actual.Z}");
            }
        }
    }
}

I have kept this class in a unit-test project and named it unit_test_library.

Then, I added unit_test_library library as a reference to the actual unit test projects.

However, those projects are not finding these functions as members of the Assert class.

What is the issue?

I am using:

Visual Studio 2017
.NET Framework 4.7.2

Example usage:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using PdbLib; 

namespace PdbLibTests
{
    [TestClass]
    public class HingeMoversTests
    {
        [TestMethod]
        public void MakePredefinedMove()
        {
            MakePredefinedMoveN(1);
            //MakePredefinedHingeMoveN(7);
            //MakePredefinedHingeMoveN(8);
        }

        private void MakePredefinedMoveN(int hingeMoveSize)
        {
            int residue_count = 3;

            // Setup random generator
            Random random = new Random(42);
            PdbLib.System model = PdbLib.System.MakeRandom(new int[] { residue_count }, 100.0, random);

            // Initialize internal coordinates
            double[] r = new double[residue_count];
            double[] planar = new double[residue_count];
            double[] dihedral = new double[residue_count];
            Vec3[] coords = new Vec3[residue_count];

            for (int i = 0; i < residue_count; i++)
            {
                r[i] = 1.0;
                planar[i] = (90.0).ToRadian();
                dihedral[i] = (180.0).ToRadian();
                coords[i] = new Vec3();
            }

            NeRF.RestoreLinearChain(r, planar, dihedral, ref coords);//(0,0,0), (1,0,0), (1,1,0)

            for (int i = 0; i < residue_count; i++)
            {
                model.Vec3ToCa(i, coords[i]);//(0,0,0), (42949672, 0, 0), (42949672, 42949672, 0)
            }

            AtomMover mover = new AtomMover(hingeMoveSize, Math.PI / 2.0, Math.PI / 2.0);
            MoveProposal mp = new MoveProposal(hingeMoveSize);//(0,0,0)

            Vec3 v0Before = model.CaToVec3(0);//0,0,0
            Vec3 v1Before = model.CaToVec3(1);//1,0,0
            Vec3 lastBefore = model.CaToVec3(hingeMoveSize + 1);//1,1,0

            mover.ComputeMove(model, 1, Math.PI / 2, ref mp);//mp = (42949672, 0, -30370005)
            mp.Apply(ref model);//model = (0,0,0), (42949672, 0, -30370005), (42949672,42949672,0)

            Vec3 v0After = model.CaToVec3(0);//0,0,0
            Vec3 v1After = model.CaToVec3(1);//1,0,0
            Vec3 lastAfter = model.CaToVec3(hingeMoveSize + 1);//1,1,0

            Assert.AssertVec3Equal(v0Before, v0After, 1e-5, "First CA should remain unchanged.");
            Assert.AssertVec3Equal(lastBefore, lastAfter, 1e-5, "Last CA should remain unchanged.");
            
            double dihedralMovedDegrees = Vec3Helper.DihedralAngle4(v1Before, v0Before, lastBefore, v1After).ToDegrees();

            Assert.AreEqual(90.0, Math.Abs(dihedralMovedDegrees), 0.01, "Dihedral angle should change by 90 degrees.");
        }        
    }
}

Solution

If you define extension methods for the Assert class of MsTest, you should use them via the That property of this class. In your case, this is

Assert.That.AssertVec3NotEqual(vector1, vector2, tolerance);

If you omit the Assertfrom the name of the method, you will even get a phrase that reads like an English sentnece: Assert that vec3 are not equal.