test: add test for cache verification

Context: #81 (comment)

Co-authored-by: Gregor Martynus <[email protected]>

.gitignore

@@ -1,2 +1,2 @@
 node_modules
-coverage
+coverage

example.js

@@ -0,0 +1,28 @@
+import { request } from "@octokit/request";
+import { fetchVerificationKeys } from "./index.js";
+
+async function main() {
+    const token = process.env.GITHUB_TOKEN;
+    if (!token) throw new Error("GITHUB_TOKEN is not defined");
+
+    const r = request.defaults({
+        headers: {
+            Authorization: `token ${token}`,
+        }
+    });
+
+    const { id, keys } = await fetchVerificationKeys({ token });
+    const cache = { id, keys };
+
+    const firstRateLimitCheck = await r("GET /rate_limit");
+    const firstRateLimitRemaining = firstRateLimitCheck.data.resources.core.remaining;
+    console.log("Rate limit after fetching keys:", firstRateLimitRemaining);
+
+    const response = await fetchVerificationKeys({ token, cache });
+
+    const secondRateLimitCheck = await r("GET /rate_limit");
+    const secondRateLimitRemaining = secondRateLimitCheck.data.resources.core.remaining;
+    console.log("Rate limit after fetching keys from cache:", secondRateLimitRemaining);
+}
+
+main().catch(console.error);

test/verification.test.js

@@ -172,7 +172,7 @@ test("fetchVerificationKeys() - without cache", async (t) => {
   t.deepEqual(result, { id: "", keys: publicKeys });
 });
 
-test("fetchVerificationKeys() - with cache", async (t) => {
+test("fetchVerificationKeys() - returns cached keys on 304 response", async (t) => {
   const mockAgent = new MockAgent();
   function fetchMock(url, opts) {
     opts ||= {};
@@ -210,3 +210,72 @@ test("fetchVerificationKeys() - with cache", async (t) => {
 
   t.deepEqual(result, cache);
 });
+
+test("fetchVerificationKeys() - populates and utilizes cache correctly", async (t) => {
+  const mockAgent = new MockAgent();
+  function fetchMock(url, opts) {
+    opts ||= {};
+    opts.dispatcher = mockAgent;
+    return fetch(url, opts);
+  }
+
+  mockAgent.disableNetConnect();
+  const mockPool = mockAgent.get("https://api.github.com");
+
+  // First request: respond with 200 and etag header
+  mockPool
+    .intercept({
+      method: "get",
+      path: `/meta/public_keys/copilot_api`,
+    })
+    .reply(
+      200,
+      {
+        public_keys: publicKeys,
+      },
+      {
+        headers: {
+          "content-type": "application/json",
+          "etag": "etag-value",
+          "x-request-id": "<request-id>",
+        },
+      },
+    );
+
+  const testRequest = defaultRequest.defaults({
+    request: { fetch: fetchMock },
+  });
+
+  // First call to fetchVerificationKeys to populate the cache
+  const firstResult = await fetchVerificationKeys({
+    request: testRequest,
+  });
+
+  const expectedCache = { id: "etag-value", keys: publicKeys };
+  t.deepEqual(firstResult, expectedCache);
+
+  // Second request: respond with 304
+  mockPool
+    .intercept({
+      method: "get",
+      path: `/meta/public_keys/copilot_api`,
+    })
+    .reply(
+      304,
+      {},
+      {
+        headers: {
+          "content-type": "application/json",
+          "x-request-id": "<request-id>",
+        },
+      },
+    );
+
+  // Second call to fetchVerificationKeys with cache
+  const secondResult = await fetchVerificationKeys({
+    request: testRequest,
+    cache: expectedCache,
+  });
+
+  t.deepEqual(secondResult, expectedCache);
+});