feat: add statement removal mutation operator - #87
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Add StatementRemovalMutator that removes increment/decrement, defer, go, and channel send statements by replacing them with an empty statement, testing whether their side effects are covered by tests. Assignment and expression statements are intentionally excluded; they are handled by the dedicated assignment_removal and expression_removal mutators to avoid generating duplicate mutants. Closes #6
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🧬 Mutation Testing Results✅ Quality Gate: PASSED Overall Mutation Score: 63.2% Files with Mutations
Generated by gomu mutation testing |
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Summary
StatementRemovalMutatorthat removes statements carrying a side effect by replacing them with an empty statementi++,i--),defer,go, and channel send (ch <- v)CursorApplierinterface for node replacementDisambiguation from related issues
One of three statement-removal operators, partitioned by node type to avoid duplicate mutants:
*ast.AssignStmt*ast.ExprStmt*ast.IncDecStmt,*ast.DeferStmt,*ast.GoStmt,*ast.SendStmtAssignStmtandExprStmtare explicitly excluded here so the three operators never target the same node.Changes
internal/mutation/statementremoval.go— new mutatorinternal/mutation/statementremoval_test.go— unit tests (incl.ApplyWithCursor)internal/mutation/registry.go— regenerated (8 mutators)internal/mutation/engine_test.go— updated mutator count/listinternal/execution/overlay_test.go+ testdata — end-to-end golden testREADME.md— documented the new mutation typeTest plan
go build ./...,go vet ./...,go test ./...TestMutateAndApplyIntegrationcovers removing*counter++make lint(pinned golangci-lint) reports 0 issuesCloses #6