0Pricing
C# Academy · Lesson

xUnit/MSTest setup, assertions

Learn test shape (Arrange-Act-Assert), see how assertions fail tests, and map the ideas to MSTest/xUnit attributes.

What is a unit test?

Goal: Write small, repeatable unit tests.

  • Separate test project uses MSTest or xUnit
  • Each test checks one behavior
  • Use clear names and assertions

AAA pattern

Tests follow Arrange → Act → Assert. Here we simulate an assertion with a simple check.

using System;

public static class MathUtil
{
  // Method under test
  public static int Add(int a, int b)
  {
    return a + b;
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    // Arrange
    int a = 2;
    int b = 3;
    int expected = 5;

    // Act
    int actual = MathUtil.Add(a, b);

    // Assert (manual check for this console demo)
    if (actual == expected)
      Console.WriteLine("PASS: Add returned " + actual);
    else
      Console.WriteLine("FAIL: expected " + expected + " but got " + actual);
  }
}

All lessons in this course

  1. xUnit/MSTest setup, assertions
  2. Fakes via interfaces; test data builders
  3. Debugging failing tests
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