test(ignore): run race regression check in CI

Run the ignore package with the race detector in the build-test workflow. Document that the concurrent root-pattern test needs -race because matching assertions can pass despite concurrent writes.

Signed-off-by: Alexandre Rodrigues <alexandre3ylf@gmail.com>

.github/workflows/build-test.yml

@@ -32,5 +32,7 @@ jobs:
         run: go mod tidy -diff
       - name: Run unit tests
         run: make test-coverage
+      - name: Test ignore rules with the race detector
+        run: go test -race ./pkg/ignore
       - name: Test build
         run: make build

pkg/ignore/rules_test.go

@@ -136,6 +136,7 @@ func parseString(str string) (*Rules, error) {
 }
 
 func TestIgnoreRootPatternConcurrent(t *testing.T) {
+	// Run with -race to detect concurrent writes even when matching results agree.
 	rules, err := parseString("/root.txt")
 	require.NoError(t, err)
 	var workers sync.WaitGroup