fix: limit request body

src/comment-templates.ts

@@ -1,6 +1,9 @@
 import { Result } from 'eslint-remote-tester/dist/exports-for-compare-action';
 import { requirePeerDependency } from './peer-dependencies';
 
+// Github API limits body length to 65536. Let's leave some paddings just to be sure.
+const RESULTS_MAX_LENGH = 62000;
+
 const filterUniqueTruthy = <T>(item: T, index: number, array: T[]) =>
     item != null && array.indexOf(item) === index;
 
@@ -11,7 +14,7 @@ const formatRule = (rule: string | null) => '\n-   `' + rule + '`';
  * Template for building github issue comment when action run into error
  */
 export const ERROR_TEMPLATE = (error: Error): string =>
-`Something went wrong.
+`Something went wrong. This is likely an internal error of \`eslint-remote-tester-run-action\`.
 
 <details>
     <summary>Click to expand</summary>
@@ -50,12 +53,12 @@ ${limitReached ?
 Reached maximum result count ${maxResultCount}.
 Showing ${limitedResults.length}/${results.length}
 ` : ''}
-Rules:${rules.map(formatRule).join('')}
+Rules:${rules.filter(Boolean).map(formatRule).join('')}
 
 <details>
     <summary>Click to expand</summary>
 
-${limitedResults.map(template).join('\n')}
+${limitedResults.map(template).join('\n').slice(0, RESULTS_MAX_LENGH)}
 </details>
 `;
 };

test/__mocks__/GithubAPI.mock.ts

@@ -8,6 +8,13 @@ export const onComment = jest.fn();
 export const onIssueCreated = jest.fn();
 export const expectedIssueNumber = 999;
 
+const ERROR_BODY_MAX_LENGTH = {
+    resource: 'Issue',
+    code: 'custom',
+    field: 'body',
+    message: 'body is too long (maximum is 65536 characters)',
+} as const;
+
 export default setupServer(
     rest.get(`${API_URL}/search/issues`, (req, res, ctx) => {
         const q = req.url.searchParams.get('q');
@@ -52,6 +59,10 @@ export default setupServer(
             const { owner, repo, issueNumber } = req.params;
             const body = req.body;
 
+            if (body?.length > 65536) {
+                return res(ctx.json(ERROR_BODY_MAX_LENGTH), ctx.status(400));
+            }
+
             // Void endpoint tested via additional assertion
             onComment({ owner, repo, issueNumber, body });
 
@@ -62,6 +73,10 @@ export default setupServer(
         const { owner, repo, title } = req.params;
         const body = req.body;
 
+        if (body?.length > 65536) {
+            return res(ctx.json(ERROR_BODY_MAX_LENGTH), ctx.status(400));
+        }
+
         // Void endpoint tested via additional assertion
         onIssueCreated({ owner, repo, title, body });
 

test/comment-templates.test.ts

@@ -178,14 +178,29 @@ describe('COMMENT_TEMPLATE', () => {
             "
         `);
     });
+
+    test('length of results are limited below 65K characters', () => {
+        const results = [
+            generateResult(1),
+            generateResult(2),
+            generateResult(3),
+        ].map(result => ({
+            ...result,
+            error: 'Extremely long stacktrace'.repeat(10000),
+        }));
+
+        const comment = COMMENT_TEMPLATE(results, 3, 50);
+
+        expect(comment.length).toBeLessThan(65000);
+    });
 });
 
 describe('ERROR_TEMPLATE', () => {
     test('error stack is shown', () => {
         const comment = ERROR_TEMPLATE(mockError);
 
         expect(comment).toMatchInlineSnapshot(`
-            "Something went wrong.
+            "Something went wrong. This is likely an internal error of \`eslint-remote-tester-run-action\`.
 
             <details>
                 <summary>Click to expand</summary>