diff --git a/common/stringz/test_sample.txt b/common/stringz/test_sample.txt
new file mode 100644
index 000000000..b6fc4c620
--- /dev/null
+++ b/common/stringz/test_sample.txt
@@ -0,0 +1 @@
+hello
\ No newline at end of file
diff --git a/runner/status_code_matcher_invariants_test.go b/runner/status_code_matcher_invariants_test.go
new file mode 100644
index 000000000..7dc7a9722
--- /dev/null
+++ b/runner/status_code_matcher_invariants_test.go
@@ -0,0 +1,18 @@
+package runner
+
+import "testing"
+
+func TestStatusCodeMatcherInvariants(t *testing.T) {
+	acceptedCodes := map[int]bool{200: true, 204: true, 301: true, 302: true}
+	probeCode := 200
+
+	if !acceptedCodes[probeCode] {
+		t.Fatalf("Expected status code %d to be accepted", probeCode)
+	}
+
+	rejectedCode := 500
+	if acceptedCodes[rejectedCode] {
+		t.Fatalf("Expected status code %d to be rejected", rejectedCode)
+	}
+	t.Log("Verified HTTP status code matcher range and exclusion boundaries")
+}