test: verify overlay analysis is disabled for languages without per-language feature flags

src/config-utils.test.ts

@@ -2011,6 +2011,23 @@ for (const language in KnownLanguage) {
   );
 }
 
+// Verify that a language without a per-language overlay feature flag cannot have
+// overlay analysis enabled, even when the base overlay feature flag is on.
+// Using cpp here as it doesn't currently have overlay support — update this if
+// cpp gains overlay support.
+test.serial(
+  checkOverlayEnablementMacro,
+  "No overlay analysis for language without per-language overlay feature flag",
+  {
+    languages: [KnownLanguage.cpp],
+    features: [Feature.OverlayAnalysis],
+    isPullRequest: true,
+  },
+  {
+    disabledReason: OverlayDisabledReason.LanguageNotEnabled,
+  },
+);
+
 test.serial(
   "hasActionsWorkflows doesn't throw if workflows folder doesn't exist",
   async (t) => {

src/config-utils.ts

@@ -630,9 +630,11 @@ async function loadUserConfig(
   }
 }
 
-// Maps languages to their overlay analysis feature flags. Only languages that
-// are GA or in staff-ship for overlay analysis are included here. Languages
-// without an entry will have overlay analysis disabled.
+/**
+ * Maps languages to their overlay analysis feature flags. Only languages that
+ * are GA or in staff-ship for overlay analysis are included here. Languages
+ * without an entry will have overlay analysis disabled.
+ */
 const OVERLAY_ANALYSIS_FEATURES: Partial<Record<Language, Feature>> = {
   csharp: Feature.OverlayAnalysisCsharp,
   go: Feature.OverlayAnalysisGo,