tests: add top langs endpoint proper cache header test (#3269)

tests/top-langs.test.js

@@ -4,7 +4,7 @@ import axios from "axios";
 import MockAdapter from "axios-mock-adapter";
 import topLangs from "../api/top-langs.js";
 import { renderTopLanguages } from "../src/cards/top-languages-card.js";
-import { renderError } from "../src/common/utils.js";
+import { renderError, CONSTANTS } from "../src/common/utils.js";
 import { expect, it, describe, afterEach } from "@jest/globals";
 
 const data_langs = {
@@ -206,4 +206,27 @@ describe("Test /api/top-langs", () => {
       renderError("Something went wrong", "Locale not found"),
     );
   });
+
+  it("should have proper cache", async () => {
+    const req = {
+      query: {
+        username: "anuraghazra",
+      },
+    };
+    const res = {
+      setHeader: jest.fn(),
+      send: jest.fn(),
+    };
+    mock.onPost("https://api.github.com/graphql").reply(200, data_langs);
+
+    await topLangs(req, res);
+
+    expect(res.setHeader).toBeCalledWith("Content-Type", "image/svg+xml");
+    expect(res.setHeader).toBeCalledWith(
+      "Cache-Control",
+      `max-age=${CONSTANTS.SIX_HOURS / 2}, s-maxage=${
+        CONSTANTS.SIX_HOURS
+      }, stale-while-revalidate=${CONSTANTS.ONE_DAY}`,
+    );
+  });
 });