microsoft/filter-syntax
Reference data for test filter syntax across all platform and framework combinations: VSTest --filter expressions, MTP filters for MSTest/NUnit/xUnit v3/TUnit, and VSTest-to-MTP filter translation. DO NOT USE directly — loaded by run-tests, mtp-hot-reload, and migrate-vstest-to-mtp when they need filter syntax.
npx skills add https://github.com/microsoft/testfx --skill filter-syntax
Filter syntax depends on the platform and test framework.
dotnet test --filter <EXPRESSION>
Expression syntax: <Property><Operator><Value>[|&<Expression>]
Operators:
| Operator | Meaning |
|----------|---------|
| = | Exact match |
| != | Not exact match |
| ~ | Contains |
| !~ | Does not contain |
Combinators: | (OR), & (AND). Parentheses for grouping: (A|B)&C
Supported properties by framework:
| Framework | Properties |
|-----------|-----------|
| MSTest | FullyQualifiedName, Name, ClassName, Priority, TestCategory |
| xUnit | FullyQualifiedName, DisplayName, Traits |
| NUnit | FullyQualifiedName, Name, Priority, TestCategory |
An expression without an operator is treated as FullyQualifiedName~<value>.
Examples (VSTest):
# Run tests whose name contains "LoginTest"
dotnet test --filter "Name~LoginTest"
# Run a specific test class
dotnet test --filter "ClassName=MyNamespace.MyTestClass"
# Run tests in a category
dotnet test --filter "TestCategory=Integration"
# Exclude a category
dotnet test --filter "TestCategory!=Slow"
# Combine: class AND category
dotnet test --filter "ClassName=MyNamespace.MyTestClass&TestCategory=Unit"
# Either of two classes
dotnet test --filter "ClassName=MyNamespace.ClassA|ClassName=MyNamespace.ClassB"
MSTest and NUnit on MTP use the same --filter syntax as VSTest (same properties, operators, and combinators). The only difference is how the flag is passed:
# .NET SDK 8/9 (after --)
dotnet test -- --filter "Name~LoginTest"
# .NET SDK 10+ (direct)
dotnet test --filter "Name~LoginTest"
xUnit v3 on MTP uses framework-specific filter flags instead of the generic --filter expression:
| Flag | Description |
|------|-------------|
| --filter-class "name" | Run all tests in a given class |
| --filter-not-class "name" | Exclude all tests in a given class |
| --filter-method "name" | Run a specific test method |
| --filter-not-method "name" | Exclude a specific test method |
| --filter-namespace "name" | Run all tests in a namespace |
| --filter-not-namespace "name" | Exclude all tests in a namespace |
| --filter-trait "name=value" | Run tests with a matching trait |
| --filter-not-trait "name=value" | Exclude tests with a matching trait |
Multiple values can be specified with a single flag: --filter-class Foo Bar.
# .NET SDK 8/9
dotnet test -- --filter-class "MyNamespace.LoginTests"
# .NET SDK 10+
dotnet test --filter-class "MyNamespace.LoginTests"
# Combine: namespace + trait
dotnet test --filter-namespace "MyApp.Tests.Integration" --filter-trait "Category=Smoke"
For complex expressions, use --filter-query with a path-segment syntax:
/<assemblyFilter>/<namespaceFilter>/<classFilter>/<methodFilter>[traitName=traitValue]
Each segment matches against: assembly name, namespace, class name, method name. Use * for "match all" in any segment. Documentation: <https://xunit.net/docs/query-filter-language>
# xUnit.net v3 MTP — using query language (assembly/namespace/class/method[trait])
dotnet test -- --filter-query "/*/*/*IntegrationTests*/*[Category=Smoke]"
TUnit uses --treenode-filter with a path-based syntax:
--treenode-filter "/<Assembly>/<Namespace>/<ClassName>/<TestName>"
Wildcards (*) are supported in any segment. Filter operators can be appended to test names for property-based filtering.
| Operator | Meaning |
|----------|---------|
| * | Wildcard match |
| = | Exact property match (e.g., [Category=Unit]) |
| != | Exclude property value |
| & | AND (combine conditions) |
| \| | OR (within a segment, requires parentheses) |
Examples (TUnit):
# All tests in a class
dotnet run --treenode-filter "/*/*/LoginTests/*"
# A specific test
dotnet run --treenode-filter "/*/*/*/AcceptCookiesTest"
# By namespace prefix (wildcard)
dotnet run --treenode-filter "/*/MyProject.Tests.Api*/*/*"
# By custom property
dotnet run --treenode-filter "/*/*/*/*[Category=Smoke]"
# Exclude by property
dotnet run --treenode-filter "/*/*/*/*[Category!=Slow]"
# OR across classes
dotnet run --treenode-filter "/*/*/(LoginTests)|(SignupTests)/*"
# Combined: namespace + property
dotnet run --treenode-filter "/*/MyProject.Tests.Integration/*/*/*[Priority=Critical]"
MSTest, NUnit, and xUnit.net v2 (with YTest.MTP.XUnit2): The VSTest --filter syntax is identical on both VSTest and MTP. No changes needed.
xUnit.net v3 (native MTP): xUnit.net v3 does NOT support the VSTest --filter syntax on MTP. Translate filters using xUnit.net v3's native options:
| VSTest --filter syntax | xUnit.net v3 MTP equivalent | Notes |
|---|---|---|
| FullyQualifiedName~ClassName | --filter-class *ClassName* | Wildcards required for substring match |
| FullyQualifiedName=Ns.Class.Method | --filter-method Ns.Class.Method | Exact match on fully qualified method |
| Name=MethodName | --filter-method *MethodName* | Wildcards for substring match |
| Category=Value (trait) | --filter-trait "Category=Value" | Filter by trait name/value pair |
| Complex expressions | --filter-query "expr" | Uses xUnit.net query filter language (see above) |
Take microsoft/filter-syntax from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.