.NET Test Runner

Run .NET tests selectively using a build-first, test-targeted workflow optimized for development speed.

Core Workflow

Follow this workflow to run tests efficiently:

Step 1: Build Solution First

Build the entire solution with minimal output to catch compile errors early:

dotnet build -p:WarningLevel=0 /clp:ErrorsOnly --verbosity minimal

Step 2: Run Specific Project Tests

Run tests for the specific test project with --no-build to skip redundant compilation:

dotnet test path/to/project --no-build --verbosity minimal

Step 3: Filter When Targeting Specific Tests

Narrow down to specific tests using filter expressions:

# By method name using FullyQualifiedName (recommended)
dotnet test --no-build --filter "FullyQualifiedName~MyTestMethod"

# By class name using FullyQualifiedName (recommended)
dotnet test --no-build --filter "FullyQualifiedName~MyTestClass"

# By parameter values in Theory tests (xUnit)
dotnet test --no-build --filter "DisplayName~paramValue"

# Combined filters
dotnet test --no-build --filter "FullyQualifiedName~Create|FullyQualifiedName~Update"

Note: Properties Name~ and ClassName= may not work reliably. Use FullyQualifiedName~ instead.

Quick Reference

Commands

Filter Operators

xUnit Filter Properties

When to use DisplayName: Essential for filtering Theory tests by their parameter values. xUnit includes all parameter values in the DisplayName (e.g., MyTest(username: "admin", age: 30)), making it ideal for running specific test cases. See references/theory-parameter-filtering.md for detailed guidance.

Common Filter Patterns

# Run tests containing "Create" in method name
dotnet test --no-build --filter "FullyQualifiedName~Create"

# Run tests in a specific class
dotnet test --no-build --filter "FullyQualifiedName~UserServiceTests"

# Run tests matching namespace pattern
dotnet test --no-build --filter "FullyQualifiedName~MyApp.Tests.Unit"

# Run Theory tests with specific parameter value
dotnet test --no-build --filter "DisplayName~admin_user"

# Run tests with specific trait
dotnet test --no-build --filter "Category=Integration"

# Exclude slow tests
dotnet test --no-build --filter "Category!=Slow"

# Combined: class AND parameter value (Theory tests)
dotnet test --no-build --filter "FullyQualifiedName~OrderTests&DisplayName~USD"

# Multiple parameter values (OR condition)
dotnet test --no-build --filter "DisplayName~EUR|DisplayName~GBP"

ITestOutputHelper Output

To see output from xUnit's ITestOutputHelper, use the console logger with detailed verbosity:

dotnet test --no-build --logger "console;verbosity=detailed"

Reducing Output Noise

Verbosity levels for dotnet test:

To see test output, use grep to filter out discovery messages (for xUnit):

dotnet test --no-build --logger "console;verbosity=detailed" 2>&1 | grep -v "Discovered \[execution\]"

Framework Differences

This skill focuses on xUnit. For MSTest or NUnit, filter property names differ:

Progressive Disclosure

For advanced scenarios, load additional references:

• references/theory-parameter-filtering.md - Filtering xUnit Theory tests by parameter values (string, numeric, boolean, etc.)
• references/blame-mode.md - Debugging test crashes and hangs with --blame
• references/parallel-execution.md - Controlling parallel test execution

Load these references when:

• Working with xUnit Theory tests and need to filter by specific parameter values
• Tests are crashing or hanging unexpectedly
• Diagnosing test isolation issues
• Optimizing test run performance

When to Use This Skill

Invoke when the user needs to:

• Run targeted tests during development
• Filter tests by method or class name
• Filter xUnit Theory tests by specific parameter values (e.g., run only admin user test cases)
• Understand test output and filtering options
• Debug failing or hanging tests