MSTest Testing Skill
Core Patterns
Basic Test
csharp
using Microsoft.VisualStudio.TestTools.UnitTesting;
[TestClass]
public class CalculatorTests
{
private Calculator _calc;
[TestInitialize]
public void SetUp() => _calc = new Calculator();
[TestMethod]
public void Add_TwoNumbers_ReturnsSum()
{
Assert.AreEqual(5, _calc.Add(2, 3));
}
[TestMethod]
[ExpectedException(typeof(DivideByZeroException))]
public void Divide_ByZero_Throws()
{
_calc.Divide(10, 0);
}
}
Data-Driven Tests
csharp
[DataTestMethod]
[DataRow(2, 3, 5)]
[DataRow(-1, 1, 0)]
[DataRow(0, 0, 0)]
public void Add_Parameterized(int a, int b, int expected)
{
Assert.AreEqual(expected, _calc.Add(a, b));
}
[DataTestMethod]
[DynamicData(nameof(GetTestData), DynamicDataSourceType.Method)]
public void Add_DynamicData(int a, int b, int expected)
{
Assert.AreEqual(expected, _calc.Add(a, b));
}
private static IEnumerable<object[]> GetTestData()
{
yield return new object[] { 1, 2, 3 };
yield return new object[] { 10, -5, 5 };
}
Assertions
csharp
Assert.AreEqual(expected, actual); Assert.AreNotEqual(unexpected, actual); Assert.IsTrue(condition); Assert.IsFalse(condition); Assert.IsNull(obj); Assert.IsNotNull(obj); Assert.IsInstanceOfType(obj, typeof(MyClass)); Assert.ThrowsException<ArgumentException>(() => Method()); CollectionAssert.Contains(list, item); CollectionAssert.AreEquivalent(expected, actual); StringAssert.Contains(str, "substring"); StringAssert.StartsWith(str, "prefix"); StringAssert.Matches(str, new Regex(@"\d+"));
Lifecycle
code
[AssemblyInitialize] → Once per assembly (static) [ClassInitialize] → Once per class (static) [TestInitialize] → Before each test [TestMethod] → Test [TestCleanup] → After each test [ClassCleanup] → Once after class (static) [AssemblyCleanup] → Once after assembly (static)
Categories
csharp
[TestMethod, TestCategory("Smoke")]
public void QuickTest() { }
[TestMethod, Ignore("Bug #456")]
public void SkippedTest() { }
[TestMethod, Timeout(5000)]
public void TimedTest() { }
Setup: dotnet add package MSTest.TestFramework MSTest.TestAdapter Microsoft.NET.Test.Sdk
Run: dotnet test or dotnet test --filter "TestCategory=Smoke"
Deep Patterns
See reference/playbook.md for production-grade patterns:
| Section | What You Get |
|---|---|
| §1 Project Setup | .csproj deps, .runsettings with parallel + coverage config |
| §2 Test Patterns | TestMethod, DataTestMethod, DynamicData, exception testing |
| §3 FluentAssertions | AssertionScope, async exceptions, collection assertions |
| §4 Class & Assembly Initialize | Testcontainers, shared expensive setup, global config |
| §5 WebApplicationFactory | API integration tests with in-memory DB |
| §6 Bogus Test Data | Faker patterns for realistic data generation |
| §7 TestContext & Logging | Diagnostic output, categories, timeouts |
| §8 CI/CD Integration | GitHub Actions with coverage reporting and thresholds |
| §9 Debugging Table | 12 common problems with causes and fixes |
| §10 Best Practices | 14-item production checklist |