test(engine): cover remaining directives.go branches and remove dead code#1
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matuszeg merged 1 commit intofeat/nomutant-directivefrom Apr 29, 2026
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…code Codecov flagged four uncovered lines in internal/engine/directives.go. Two of them were genuinely missing tests — the nil-receiver guard in isSuppressed and the empty-name "continue" inside parseDirective's comma-split loop — and are now exercised by new unit tests. The other two were a *ast.Comment guard inside both collectTokenLines and largestNodeStartingAtLine that turn out to be unreachable, because the preceding *ast.CommentGroup guard already returns false from the ast.Inspect callback and ast.Inspect therefore never descends into the CommentGroup's *ast.Comment children. Removed both as dead code and noted in a comment why no Comment guard is needed.
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Summary
Internal review branch addressing the four lines Codecov flagged on
internal/engine/directives.go(lines 68, 168, 214, 268 of the version onfeat/nomutant-directive@1ca72c6).isSuppressed. Now exercised byTestDirectiveIndex_NilReceiverIsSafe, which calls(*directiveIndex)(nil).isSuppressed(...)and confirms it returnsfalsewithout panicking.continueinside the comma-split loop inparseDirective, hit when an empty entry appears (e.g.//nomutant:arithmetic-base,,invert-bitwise). Now exercised byTestBuildDirectiveIndex_TypedFilterWithEmptyEntries.*ast.Commentguards insidecollectTokenLinesandlargestNodeStartingAtLine. Removed as unreachable: the preceding*ast.CommentGroupguard already returnsfalsefrom theast.Inspectcallback, so the walker never descends into the CommentGroup's*ast.Commentchildren. Added a comment explaining why no Comment guard is needed.Test plan
go test -race ./internal/engine/...— all greenmake lint— 0 issuesgo tool cover -funcondirectives.go— every function reports 100.0%If this looks good, merging it into
feat/nomutant-directivewill update the real PR (go-gremlins#279) with the coverage and dead-code fixes.