test: add test for invalid ADMIN_SDK_JSON

src/libs/fcm/verifyFcm.spec.ts

@@ -37,4 +37,15 @@ describe("verifyFcmToken", () => {
 
     expect(res).toBeFalse();
   });
+
+  it("invalid ADMIN_SDK_JSON, returns false", async () => {
+    const token =
+      "7v8sy43aq0re4r8xe7rmr0cn1fsmh6phehnfla2pa73z899zmhyarivmkt4sj6pyv0py43u6p2sim6wz2vg9ypjp9rug1keoth7f6ll3gdvas4q020u3ah51r6bjgn51j6bd92ztmtof3ljpcm8q31njvndy65enm68";
+    const res = await verifyFcmToken(token, {
+      ...FAKE_ADMIN_SDK_JSON,
+      clientEmail: "",
+    });
+
+    expect(res).toBeFalse();
+  });
 });