Test fallback when repo has no submodules

Author: henrymercer

lib/analyze-action-post.js

@@ -1959,6 +1959,20 @@ test.serial(
   },
 );
 
+test.serial(
+  checkOverlayEnablementMacro,
+  "Overlay enabled when git version cannot be determined and repo has no submodules",
+  {
+    overlayDatabaseEnvVar: "overlay",
+    gitVersion: undefined,
+    hasSubmodules: false,
+  },
+  {
+    overlayDatabaseMode: OverlayDatabaseMode.Overlay,
+    useOverlayDatabaseCaching: false,
+  },
+);
+
 test.serial(
   checkOverlayEnablementMacro,
   "No overlay when disabled via repository property",