Extract zero-results SARIF fixture into helper function

Address code review feedback: extract inline SARIF object into
createZeroResultsSarif() helper for consistency with existing patterns.

Agent-Logs-Url: https://github.com/advanced-security/codeql-development-mcp-server/sessions/7ea1caeb-de6d-40cd-b045-3dd634602403

Co-authored-by: data-douser <70299490+data-douser@users.noreply.github.com>

Author: Copilot

server/test/src/tools/sarif-tools.test.ts

@@ -70,6 +70,25 @@ function createTestSarif() {
   };
 }
 
+/** SARIF with a defined rule but zero results — validates resultCount: 0 */
+function createZeroResultsSarif() {
+  return {
+    version: '2.1.0',
+    runs: [{
+      tool: {
+        driver: {
+          name: 'CodeQL',
+          version: '2.25.1',
+          rules: [
+            { id: 'js/unused-variable', shortDescription: { text: 'Unused variable' } },
+          ],
+        },
+      },
+      results: [],
+    }],
+  };
+}
+
 // ---------------------------------------------------------------------------
 // Tests
 // ---------------------------------------------------------------------------
@@ -231,23 +250,8 @@ describe('SARIF Tools', () => {
       });
 
       it('should return resultCount 0 for rules with no results', async () => {
-        const noResultsSarif = {
-          version: '2.1.0',
-          runs: [{
-            tool: {
-              driver: {
-                name: 'CodeQL',
-                version: '2.25.1',
-                rules: [
-                  { id: 'js/unused-variable', shortDescription: { text: 'Unused variable' } },
-                ],
-              },
-            },
-            results: [],
-          }],
-        };
         const noResultsPath = join(testStorageDir, 'no-results.sarif');
-        writeFileSync(noResultsPath, JSON.stringify(noResultsSarif));
+        writeFileSync(noResultsPath, JSON.stringify(createZeroResultsSarif()));
 
         const result = await handlers.sarif_list_rules({ sarifPath: noResultsPath });
         const parsed = JSON.parse(result.content[0].text);