chore: prlinter crashes if it runs alongside itself (#33129)

There is a race condition between multiple runs of the PR linter: it
finds a review that it wants to dismiss, but if that already has been
dismissed by another PR linter running in parallel the API call fails
and the linter does too.

Catch this specific case.

----

*By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license*

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

tools/@aws-cdk/prlint/linter-base.ts

@@ -168,6 +168,11 @@ export class PullRequestLinterBase {
           message,
         });
       } catch (e: any) {
+        if (githubResponseErrors(e).includes('Can not dismiss a dismissed pull request review')) {
+          // Can happen because of race conditions. We already achieved the result we wanted, so ignore.
+          continue;
+        }
+
         // This can fail with a "not found" for some reason
         throw new Error(`Dismissing review failed, user is probably not authorized: ${JSON.stringify(e, undefined, 2)}`);
       }
@@ -386,4 +391,11 @@ export function mergeLinterActions(a: LinterActions, b: LinterActions): LinterAc
 
 function nonEmpty<A>(xs: A[]): A[] | undefined {
   return xs.length > 0 ? xs : undefined;
+}
+
+/**
+ * Return error messages from an exception thrown by GitHub
+ */
+function githubResponseErrors(e: Error): string[] {
+  return (e as any).response?.data?.errors ?? [];
 }

tools/@aws-cdk/prlint/test/linter-base.test.ts

@@ -21,7 +21,7 @@ const linter = new PullRequestLinterBase({
 });
 
 beforeEach(() => {
-  jest.clearAllMocks();
+  jest.resetAllMocks();
 
   octomock.pulls.get.mockReturnValue({
     data: {
@@ -34,6 +34,66 @@ beforeEach(() => {
   octomock.repos.listCommitStatusesForRef.mockReturnValue({ data: [] });
 });
 
+test('ignore if dismissing reviews throws a specific "already dismissed" error', async () => {
+  // GIVEN
+  octomock.pulls.listReviews.mockReturnValue({
+    data: [
+      {
+        id: 1111,
+        user: { login: 'aws-cdk-automation' },
+        state: 'CHANGES_REQUESTED',
+        body: 'some comment',
+      },
+    ]
+  });
+  octomock.pulls.dismissReview.mockRejectedValue({
+    status: 422,
+    response: {
+      data: {
+        errors: [
+          'Can not dismiss a dismissed pull request review',
+        ],
+      },
+    },
+  });
+
+  // WHEN
+  await linter.executeActions({
+    dismissPreviousReview: true,
+  });
+
+  // THEN: no error
+});
+
+test('throw if dismissing reviews throws any other error', async () => {
+  // GIVEN
+  octomock.pulls.listReviews.mockReturnValue({
+    data: [
+      {
+        id: 1111,
+        user: { login: 'aws-cdk-automation' },
+        state: 'CHANGES_REQUESTED',
+        body: 'some comment',
+      },
+    ]
+  });
+  octomock.pulls.dismissReview.mockRejectedValue({
+    status: 422,
+    response: {
+      data: {
+        errors: [
+          'Review not found',
+        ],
+      },
+    },
+  });
+
+  // THEN
+  await expect(linter.executeActions({
+    dismissPreviousReview: true,
+  })).rejects.toThrow(/Dismissing review failed/);
+});
+
 test('dismissing a review dismisses and changes the text of all previous reviews', async () => {
   // GIVEN
   octomock.pulls.listReviews.mockReturnValue({