Add overlay migration regression coverage

records_test.go

@@ -0,0 +1,22 @@
+package configkit
+
+import "testing"
+
+func TestOverlayPublicValues(t *testing.T) {
+	if LayerOverlay != "overlay" {
+		t.Fatalf("LayerOverlay = %q", LayerOverlay)
+	}
+	for code, value := range map[Code]string{
+		CodeOverlayInvalid:       "overlay.invalid",
+		CodeOverlayMissing:       "overlay.missing",
+		CodeOverlayOutsideRoot:   "overlay.outside_root",
+		CodeOverlayRepeated:      "overlay.repeated",
+		CodeOverlayDirective:     "overlay.directive",
+		CodeOverlayVersion:       "overlay.version",
+		CodeOverlayLimitExceeded: "overlay.limit_exceeded",
+	} {
+		if string(code) != value {
+			t.Errorf("code = %q, want %q", code, value)
+		}
+	}
+}