# Nunit Constraint Documentation > Create and update documentation for NUnit constraints following the established template structure Use when this capability is needed. - Skill: `tomevault-io/nunit-constraint-documentation` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/nunit-constraint-documentation` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/nunit-constraint-documentation/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Docs & Writing - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/nunit-constraint-documentation --- # NUnit Constraint Documentation This skill describes how to create and update documentation for NUnit constraints. ## Documentation Template Structure Each constraint documentation file in `docs/articles/nunit/writing-tests/constraints/` should follow this structure: ````markdown --- uid: constraint- --- # Constraint Brief description (2-3 sentences) explaining what the constraint tests and when to use it. ## Usage ```csharp Is.(args) // Primary syntax Does.(args) // If applicable Has.(args) // If applicable ``` ## Modifiers ```csharp .IgnoreCase // Makes comparison case-insensitive .Using(IComparer comparer) // Uses custom comparison logic .Within(tolerance) // Allows approximate matching ``` > [!NOTE] > Only include this section if the constraint has modifiers. ## Examples Inline one-liners showing common patterns: ```csharp Assert.That(actual, Is.(expected)); Assert.That(actual, Is.Not.(expected)); Assert.That(actual, Is.(expected).IgnoreCase); ``` ### [Scenario Section - only if complex setup needed] Brief explanation of the scenario. [!code-csharp[ScenarioExample](~/snippets/Snippets.NUnit/ConstraintExamples.cs#ScenarioExample)] ## Notes 1. Important behavioral notes 2. Edge cases 3. Compatibility information ## See Also * [Related Constraint](related.md) * [Another Related](another.md) ```` ## Key Structural Principles | Section | Purpose | |---------|---------| | Usage (first) | Users interact with fluent API (`Is.*`, `Does.*`), not constructors | | Modifiers | Use `.ModifierName` format (shows method chaining) | | Examples | Inline one-liners for common patterns | | Notes | Edge cases and important behaviors | | See Also | Links to related constraints | ## Inline vs External Examples **Inline examples** (in the markdown itself): - **Usage section**: Always inline - shows the API surface (1-3 lines of just the syntax) - **Examples section**: One-liners demonstrating common patterns without test boilerplate ````markdown ## Usage ```csharp Is.Null Is.Not.Null ``` ## Examples ```csharp Assert.That(myObject, Is.Null); Assert.That(myString, Is.Not.Null); Assert.That(GetResult(), Is.Null.Or.Empty); // Combined with other constraints ``` ```` **External snippets** (from Snippets.NUnit): - Complex scenarios requiring setup code (custom comparers, test data, helper classes) - Full compilable test methods that verify the documentation is correct - Scenarios where the setup/context is important to understand ````markdown ### Using Custom Comparers [!code-csharp[EqualWithComparer](~/snippets/Snippets.NUnit/ConstraintExamples.cs#EqualWithComparer)] ```` **Never inline:** - Full `[Test] public void...` methods - those go in external snippets - Examples requiring helper classes or significant setup ## UID Standardization All constraint UIDs should follow the pattern: `constraint-` Examples: - `equalconstraint` → `constraint-equal` - `nullconstraint` → `constraint-null` - `greaterthanconstraint` → `constraint-greaterthan` ## Workflow for Updating Constraint Documentation > **Repository Layout Assumption**: This workflow assumes you have cloned both repositories as siblings: > - `/nunit/` - The NUnit framework source code ([nunit/nunit](https://github.com/nunit/nunit)) > - `/docs/` - This documentation repository ([nunit/docs](https://github.com/nunit/docs)) > > Adjust paths below to match your local setup. ### Step 1: Find the Source Code Search for the constraint class in the NUnit framework: ```shell # Find the constraint source file (adjust path to your nunit repo location) grep -r "class Constraint" ../nunit/src/NUnitFramework/framework/Constraints --include="*.cs" ``` The source is typically at: `/src/NUnitFramework/framework/Constraints/Constraint.cs` ### Step 2: Analyze the Source Code From the source file, extract: - Available syntax helpers (check `Is.cs`, `Does.cs`, `Has.cs`, `Contains.cs`) - Modifier methods and their purposes - Constructor parameters (for reference, not for documentation focus) - Any special behaviors or edge cases from XML doc comments ### Step 3: Check for Existing Unit Tests ```shell # Find unit tests for the constraint (adjust path to your nunit repo location) grep -r "Constraint" ../nunit/src/NUnitFramework/tests --include="*.cs" ``` Unit tests provide good examples of usage patterns and edge cases. ### Step 4: Update the Markdown Documentation Follow the template structure above. Key points: - Lead with Usage section showing the fluent API - Include inline examples for quick reference - Add external snippet references for complex scenarios - Document all available modifiers with brief descriptions ### Step 5: Update or Create Snippet Examples If complex scenarios need external snippets, add them to: `docs/snippets/Snippets.NUnit/ConstraintExamples.cs` Use regions to organize: ```csharp #region ConstraintExamples [Test] public void Constraint_WithCustomComparer() { // Example with setup that's too complex for inline var comparer = new MyCustomComparer(); Assert.That(actual, Is.(expected).Using(comparer)); } #endregion ``` ### Step 6: Build and Test Always verify the snippets compile and tests pass. From the docs repository root: ```shell # Build dotnet build docs/snippets/Snippets.slnx # Run all tests dotnet test docs/snippets/Snippets.slnx --no-build # Run specific constraint tests dotnet test docs/snippets/Snippets.slnx --no-build --filter "FullyQualifiedName~ConstraintExamples" --verbosity normal ``` ## Quality Checklist Before marking a constraint as done: - [ ] UID follows `constraint-` pattern - [ ] Description is 2-3 sentences explaining purpose - [ ] Usage section shows fluent API methods (inline, 1-3 lines) - [ ] Modifiers section (if applicable) with brief descriptions - [ ] Examples section with inline one-liners for common patterns - [ ] External snippets for complex scenarios (custom comparers, setup-heavy) - [ ] Examples have subsection headers if multiple scenarios exist - [ ] Notes section for edge cases/important behaviors - [ ] See Also links to related constraints - [ ] Version info for features added after NUnit 3.0 ## Common Constraint Patterns ### Simple Constraints (no modifiers) Examples: `NullConstraint`, `TrueConstraint`, `FalseConstraint`, `NaNConstraint` These need minimal documentation but should still have: - Clear description - Usage showing `Is.` and `Is.Not.` - 2-3 inline examples ### Comparison Constraints (with Using/Within modifiers) Examples: `EqualConstraint`, `GreaterThanConstraint`, `LessThanConstraint` These need: - Modifiers section documenting `.Using()` and `.Within()` variants - Examples showing basic comparison and modifier usage - External snippets for custom comparer scenarios ### Collection Constraints (with collection-specific modifiers) Examples: `CollectionEquivalentConstraint`, `UniqueItemsConstraint`, `AllItemsConstraint` These need: - Modifiers section with `.IgnoreCase`, `.Using()`, `.UsingPropertiesComparer()` - Examples showing different collection types - Notes about element comparison behavior ### String Constraints (with string-specific modifiers) Examples: `StartsWithConstraint`, `SubstringConstraint`, `RegexConstraint` These need: - Modifiers for `.IgnoreCase`, `.Using(StringComparison)`, `.Using(CultureInfo)` - Examples showing case-sensitive and case-insensitive usage - Notes about culture-specific behavior where applicable --- > Source: [nunit/docs](https://github.com/nunit/docs) — distributed by [TomeVault](https://tomevault.io).