generate-mstest-filter

This skill generates MSTest filter expressions for use with dotnet test --filter. Use this when users describe tests they want to run and need a properly formatted filter expression.

When to Use This Skill

• User asks to run specific tests by name or pattern
• User wants to filter tests by class name, namespace, or method
• User wants to run tests with specific categories or priorities
• User describes a set of tests to include or exclude
• User needs help with test filter syntax for MSTest

MSTest Filter Syntax Reference

Supported Properties

Important: For xUnit tests (common in .NET Core projects), always use FullyQualifiedName or DisplayName. The Name and ClassName properties are not populated by xUnit and will result in no matches.

Operators

Boolean Operators

Instructions

1. Analyze the user's description to identify:

   • Test names, patterns, or keywords mentioned
   • Class names or namespaces referenced
   • Categories or priorities specified
   • Whether tests should be included or excluded
   • Whether the user referenced a file name (look for .cs extension or file path patterns)

2. Handle file name inputs:

   • If the user provides a file name (e.g., ChannelDbConnectionPoolTest.cs), extract the class name by removing the .cs extension
   • File names typically correspond to the test class name (e.g., SqlConnectionTest.cs → class SqlConnectionTest)
   • Use FullyQualifiedName~ClassName pattern for file-based inputs

3. Choose the appropriate property:

   • For xUnit tests (most .NET Core projects): Always use FullyQualifiedName or DisplayName
   • For MSTest only: Name and ClassName properties are also available
   • Use FullyQualifiedName~ with contains operator for maximum compatibility
   • Use TestCategory for category-based filtering (MSTest only)
   • Use Priority for priority-based filtering (MSTest only)

4. Select the correct operator:

   • Use ~ (contains) for partial matches and patterns - this is the safest default
   • Use = for exact matches only when you know the full value
   • Use != or !~ for exclusions

5. Combine conditions as needed:

   • Use | (OR) when any condition should match
   • Use & (AND) when all conditions must match
   • Use parentheses () for complex logic

6. Format the output as a complete dotnet test command:

   dotnet test --filter "<expression>"
   

7. Handle special characters:

   • Escape ! with \! on Linux/macOS shells
   • Use %2C for commas in generic type parameters
   • URL-encode special characters in Name/DisplayName values

Examples

Example 1: Run tests containing a keyword

User says: "Run all connection tests"

dotnet test --filter "FullyQualifiedName~Connection"

Example 2: Run tests in a specific class (xUnit compatible)

User says: "Run tests in SqlConnectionTest class"

dotnet test --filter "FullyQualifiedName~SqlConnectionTest"

Note: Avoid using ClassName= for xUnit tests - it won't work. Always use FullyQualifiedName~ for cross-framework compatibility.

Example 3: Run tests from a specific file

User says: "Run tests in ChannelDbConnectionPoolTest.cs"

dotnet test --filter "FullyQualifiedName~ChannelDbConnectionPoolTest"

Strip the .cs extension and use FullyQualifiedName~ with the class name.

Example 4: Run a specific test method

User says: "Run the TestOpenConnection test"

dotnet test --filter "FullyQualifiedName~TestOpenConnection"

Use FullyQualifiedName~ instead of Name= for xUnit compatibility.

Example 5: Run tests by category (MSTest only)

User says: "Run all tests in CategoryA"

dotnet test --filter "TestCategory=CategoryA"

Example 6: Run high priority tests (MSTest only)

User says: "Run priority 1 tests"

dotnet test --filter "Priority=1"

Example 7: Combine multiple conditions (AND)

User says: "Run connection tests that are priority 1"

dotnet test --filter "FullyQualifiedName~Connection&Priority=1"

Example 8: Combine multiple conditions (OR)

User says: "Run tests for SqlConnection or SqlCommand"

dotnet test --filter "FullyQualifiedName~SqlConnection|FullyQualifiedName~SqlCommand"

Example 9: Exclude tests

User says: "Run all tests except integration tests"

dotnet test --filter "FullyQualifiedName!~Integration"

Example 10: Complex filter with grouping

User says: "Run connection or command tests that are in CategoryA"

dotnet test --filter "(FullyQualifiedName~Connection|FullyQualifiedName~Command)&TestCategory=CategoryA"

Example 11: Exclude specific test method

User says: "Run all tests except TestSlowOperation"

dotnet test --filter "FullyQualifiedName!~TestSlowOperation"

Example 12: Multiple exclusions

User says: "Run tests but skip integration and performance tests"

dotnet test --filter "FullyQualifiedName!~Integration&FullyQualifiedName!~Performance"

Verification (Required)

Always verify the generated filter before presenting it to the user. Use the --list-tests flag to confirm the filter matches the expected tests:

dotnet test <project.csproj> --list-tests --filter "<your-filter>" --framework <target-framework>

Verification Steps

1. Run the list-tests command with the generated filter
2. Check the output:
   • If tests are listed → filter is valid
   • If "No test matches the given testcase filter" → filter is invalid, needs adjustment
3. If no matches, try these fixes in order:
   • Switch from ClassName= or Name= to FullyQualifiedName~
   • Remove the namespace prefix and use just the class/method name with ~
   • Try DisplayName~ as an alternative
4. Re-run verification after any changes

Example Verification

# Generate filter for "ChannelDbConnectionPoolTest" class
dotnet test src/Microsoft.Data.SqlClient/tests/UnitTests/Microsoft.Data.SqlClient.UnitTests.csproj --list-tests --filter "FullyQualifiedName~ChannelDbConnectionPoolTest" --framework net9.0

# Expected output shows matching tests:
# The following Tests are available:
#     Microsoft.Data.SqlClient.UnitTests.ConnectionPool.ChannelDbConnectionPoolTest.GetConnectionEmptyPool_ShouldCreateNewConnection(...)
#     ...

Error Handling

• If the user's description is ambiguous, ask for clarification about:

  • Whether they want exact match or contains
  • The full class name or namespace if needed
  • Whether conditions should be AND or OR

• If a filter returns no matches:

  • First, verify the test class/method exists in the project
  • Switch to FullyQualifiedName~ with contains operator
  • Check if the project uses xUnit (common in .NET Core) - if so, avoid Name and ClassName properties

• For complex filters, validate that parentheses are balanced

Additional Tips

• An expression without any operator is interpreted as FullyQualifiedName~<value>

  • Example: dotnet test --filter xyz equals dotnet test --filter "FullyQualifiedName~xyz"

• All lookups are case-insensitive

• When running on Linux/macOS, escape ! with backslash: \!

• For project-specific tests, add the project path:

  dotnet test path/to/project.csproj --filter "FullyQualifiedName~MyTest"
  

Common Pitfalls