Only consider the latest review for a user (#216)

src/approve.test.ts

@@ -145,6 +145,28 @@ test("when a review is dismissed", async () => {
   expect(createReview.isDone()).toBe(true);
 });
 
+test("when a review is dismissed, but an earlier review is approved", async () => {
+  apiMocks.getUser();
+  apiMocks.getPull();
+  apiMocks.getReviews(200, [
+    {
+      user: { login: "hmarr" },
+      commit_id: "6a9ec7556f0a7fa5b49527a1eea4878b8a22d2e0",
+      state: "APPROVED",
+    },
+    {
+      user: { login: "hmarr" },
+      commit_id: "24c5451bbf1fb09caa3ac8024df4788aff4d4974",
+      state: "DISMISSED",
+    },
+  ]);
+  const createReview = apiMocks.createReview();
+
+  await approve("gh-tok", new Context(), 101);
+
+  expect(createReview.isDone()).toBe(true);
+});
+
 test("when a review is not approved", async () => {
   apiMocks.getUser();
   apiMocks.getPull();

src/approve.ts

@@ -39,12 +39,19 @@ export async function approve(
     const prHead = pr.head.sha;
     core.info(`Commit SHA is ${prHead}`);
 
-    const alreadyReviewed = reviews.some(
-      ({ user, state }) => user?.login === login && state === "APPROVED"
-    );
+    // Only the most recent review for a user counts towards the review state
+    const latestReviewForUser = [...reviews]
+      .reverse()
+      .find(({ user }) => user?.login === login);
+    const alreadyReviewed = latestReviewForUser?.state === "APPROVED";
+
+    // If there's an approved review from a user, but there's an outstanding review request,
+    // we need to create a new review. Review requests mean that existing "APPROVED" reviews
+    // don't count towards the mergeability of the PR.
     const outstandingReviewRequest = pr.requested_reviewers?.some(
       (reviewer) => reviewer.login == login
     );
+
     if (alreadyReviewed && !outstandingReviewRequest) {
       core.info(
         `Current user already approved pull request #${prNumber}, nothing to do`