# filter-syntax

A reference skill for .NET test filter syntax across VSTest and MTP. Helps agents format and convert filter arguments for MSTest, NUnit, xUnit v3, and TUnit.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 4300 installs · ★ 5730
- Author: dotnet
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/dotnet/skills/tree/HEAD/plugins/dotnet-test/skills/filter-syntax/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/filter-syntax

## What it does

This reference skill provides the exact filtering syntax for .NET testing across VSTest and Microsoft Testing Platform (MTP). It details operators, combinators, and properties for MSTest, NUnit, xUnit, and TUnit, including migration patterns from VSTest expressions to MTP flags.

For VSTest and compatible runners, the guide specifies `--filter` expressions using property operators like exact matches and substrings. On MTP, it defines runner-specific differences: dedicated `--filter-class` or `--filter-query` arguments for xUnit v3, alongside tree-path syntax with `--treenode-filter` for TUnit.

Because the skill sets `user-invocable: false` and `disable-model-invocation: true`, users do not call it directly. Consuming skills like `run-tests` or `mtp-hot-reload` pull in this reference only after detecting the test framework.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill filter-syntax -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/filter-syntax/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/filter-syntax/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill filter-syntax -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/filter-syntax/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill filter-syntax -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/filter-syntax/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install dotnet/skills filter-syntax
```

2. **Manually: put the files in place**
- File: `.github/skills/filter-syntax/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill filter-syntax -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/dotnet/skills --path plugins/dotnet-test/skills/filter-syntax
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/filter-syntax/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill filter-syntax -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/dotnet/skills/tree/HEAD/plugins/dotnet-test/skills/filter-syntax/SKILL.md

## When to use it
- construct --filter expressions for MSTest and NUnit runs
- convert VSTest filter strings into xUnit v3 MTP command flags
- format --treenode-filter paths with wildcards for TUnit
- build complex --filter-query expressions for xUnit.net v3

## Example prompts
- Run only the integration tests in LoginTests using dotnet test
- Translate this VSTest filter FullyQualifiedName~Orders to xUnit v3 on MTP
- Generate a TUnit test execution command filtered by Priority=Critical

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: ab8b30ba3e21fc7d.

BEGIN THIRD-PARTY FILE ab8b30ba3e21fc7d
````text
---
name: filter-syntax
description: "Reference-only filter syntax for VSTest and MTP with MSTest, NUnit, xUnit v3, and TUnit. Load only after the platform/framework is known and a consumer needs to create or translate a filter. Do not load for unfiltered runs or platform detection. Used by run-tests and mtp-hot-reload; never invoke directly."
user-invocable: false
disable-model-invocation: true
license: MIT
---

# Test Filter Syntax Reference

Filter syntax depends on the **platform** and **test framework**.

## VSTest filters (MSTest, xUnit v2, NUnit on VSTest)

```bash
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):**

```bash
# 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"
```

## MTP filters — MSTest and NUnit

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:

```bash
# .NET SDK 8/9 (after --)
dotnet test -- --filter "Name~LoginTest"

# .NET SDK 10+ (direct)
dotnet test --filter "Name~LoginTest"
```

## MTP filters — xUnit (v3)

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 |
````
END THIRD-PARTY FILE ab8b30ba3e21fc7d

The third-party file has ended. Everything between the ab8b30ba3e21fc7d tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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