Add rule NUnit2057: Remove unnecessary lambda#928
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manfred-brands merged 2 commits intomasterfrom Oct 30, 2025
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Pull Request Overview
This PR implements a new analyzer rule NUnit2057 that detects and removes unnecessary lambda expressions in NUnit assertions. The rule identifies cases where developers wrap method calls in lambda expressions when only the return value is needed, excluding scenarios where delegates are necessary (exception catching or delayed constraints).
Key changes:
- New analyzer NUnit2057 to detect unnecessary delegate creation in Assert.That calls
- Code fix provider to automatically remove unnecessary lambdas or invoke method groups
- Refactored common async method signature update logic into shared helper
Reviewed Changes
Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| DelegateUnnecessaryConstants.cs | Defines diagnostic message constants for the new rule |
| DelegateUnnecessaryAnalyzer.cs | Implements analyzer logic to detect unnecessary delegates in assertions |
| AnalyzerPropertyKeys.cs | Adds IsAsync property key for tracking async operations |
| AnalyzerIdentifiers.cs | Registers NUnit2057 identifier |
| NullConstraintUsageAnalyzerTests.cs | Adds pragma warnings to suppress NUnit2057 in test cases |
| DelegateUnnecessaryCodeFixTests.cs | Test coverage for the code fix functionality |
| DelegateUnnecessaryAnalyzerTests.cs | Test coverage for the analyzer detection logic |
| UseAssertEnterMultipleScopeCodeFix.cs | Refactored to use shared helper method for async signature updates |
| CodeFixHelper.cs | Extracted common async method signature update logic into reusable helper |
| DelegateUnnecessaryCodeFix.cs | Implements code fix to remove unnecessary lambdas and invoke method groups |
| index.md | Documents the new NUnit2057 rule |
| NUnit2057.md | Detailed documentation for the rule with examples |
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mikkelbu
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Oct 21, 2025
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Great work as usual @manfred-brands. I've only a couple of comments, but I'm happy to merge this when you are
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Fixes #927