refactor: add new suggestion for comments.js and enhance filterDiff tests for better coverage

app/gitea.test.js

@@ -2,13 +2,10 @@ import { describe, it, afterEach, mock } from 'node:test';
 import assert from 'node:assert/strict';
 import axios from 'axios';
 
-// gitea.js reads env vars at module load time (ESM cache), so we test
-// the actual values baked in at import time and verify behavior via axios mocks.
-
 afterEach(() => mock.restoreAll());
 
 describe('gitea', async () => {
-  const { getPRDiff, postComment } = await import('./gitea.js');
+  const { getPRDiff, filterDiff, postComment } = await import('./gitea.js');
 
   it('getPRDiff calls Gitea diff API with Authorization header', async () => {
     let capturedUrl, capturedOpts;
@@ -48,7 +45,6 @@ describe('gitea', async () => {
       return { data: '' };
     });
     await getPRDiff();
-    // httpsAgent is undefined when GITEA_SKIP_TLS_VERIFY !== 'true'
     assert.equal(capturedOpts.httpsAgent, undefined);
   });
 
@@ -62,3 +58,32 @@ describe('gitea', async () => {
     await assert.rejects(() => postComment('test'), /api error/);
   });
 });
+
+describe('filterDiff', async () => {
+  const { filterDiff } = await import('./gitea.js');
+
+  const block = (file) => `diff --git a/${file} b/${file}\n--- a/${file}\n+++ b/${file}\n@@ -1 +1 @@\n-old\n+new\n`;
+
+  it('filters out .gitea/ blocks', () => {
+    const diff = block('.gitea/workflows/review.yaml') + block('src/index.js');
+    const result = filterDiff(diff, ['.gitea/']);
+    assert.ok(!result.includes('.gitea/'));
+    assert.ok(result.includes('src/index.js'));
+  });
+
+  it('does not filter non-.gitea/ blocks', () => {
+    const diff = block('src/index.js') + block('README.md');
+    const result = filterDiff(diff, ['.gitea/']);
+    assert.equal(result, diff);
+  });
+
+  it('returns empty string when all blocks are excluded', () => {
+    const diff = block('.gitea/workflows/review.yaml') + block('.gitea/ai-review/findings.json');
+    const result = filterDiff(diff, ['.gitea/']);
+    assert.equal(result, '');
+  });
+
+  it('returns empty string for empty diff', () => {
+    assert.equal(filterDiff('', ['.gitea/']), '');
+  });
+});