Dotnet Test Frameworks

.NET Test Framework Reference

Language-specific detection patterns for .NET test frameworks (MSTest, xUnit, NUnit, TUnit).

Test File Identification

Assertion APIs by Framework

TUnit-specific: assertions are async and must be awaited — a forgotten await causes the assertion to never run, and the test passes silently. A built-in analyzer warns when await is missing. Multiple assertions can be combined with .And / .Or chaining or grouped via Assert.Multiple().

Third-party assertion libraries: Should* (Shouldly), .Should() (FluentAssertions / AwesomeAssertions), Verify() (Verify). TUnit also ships an optional TUnit.Assertions.Should package providing FluentAssertions-style value.Should().BeEqualTo(...) on top of the same infrastructure.

Sleep/Delay Patterns

Skip/Ignore Annotations

Exception Handling — Idiomatic Alternatives

When a test uses try/catch to verify exceptions, suggest the framework-native alternative:

MSTest:

// Instead of try/catch (matches exact type):
var ex = Assert.ThrowsExactly<InvalidOperationException>(
    () => processor.ProcessOrder(emptyOrder));
Assert.AreEqual("Order must contain at least one item", ex.Message);

// Or (also matches derived types):
var ex = Assert.Throws<InvalidOperationException>(
    () => processor.ProcessOrder(emptyOrder));
Assert.AreEqual("Order must contain at least one item", ex.Message);

xUnit:

var ex = Assert.Throws<InvalidOperationException>(
    () => processor.ProcessOrder(emptyOrder));
Assert.Equal("Order must contain at least one item", ex.Message);

NUnit:

var ex = Assert.Throws<InvalidOperationException>(
    () => processor.ProcessOrder(emptyOrder));
Assert.That(ex.Message, Is.EqualTo("Order must contain at least one item"));

TUnit:

await Assert.That(() => processor.ProcessOrder(emptyOrder))
    .Throws<InvalidOperationException>()
    .WithMessage("Order must contain at least one item");

// Or, for exact-type matching (no derived types):
await Assert.That(() => processor.ProcessOrder(emptyOrder))
    .ThrowsExactly<InvalidOperationException>();

Mystery Guest — Common .NET Patterns

Integration Test Markers

Recognize these as integration tests (adjust smell severity accordingly):

• Class name contains Integration, E2E, EndToEnd, or Acceptance
• [TestCategory("Integration")] (MSTest)
• [Trait("Category", "Integration")] (xUnit)
• [Category("Integration")] (NUnit, TUnit)
• Project name ending in .IntegrationTests or .E2ETests

Setup/Teardown Methods

TUnit-specific: [BeforeEvery(Test)] / [AfterEvery(Test)] (and the Class / Assembly variants) run for every test/class/assembly across the whole test run — useful for global cross-cutting hooks. Hooks may optionally accept a context object (TestContext, ClassHookContext, etc.) and/or a CancellationToken.