🧪 add test for query timeout in wasm database engine (#171)

The `executeQuery` method in `src/core/sqlite-db.ts` contains logic to throw an error if row iteration (`stmt.step()`) exceeds the configured `queryTimeout`. However, this specific code path lacked unit test coverage.

This commit adds a test case to `tests/unit/sqlite-db.test.ts` within the `WasmDatabaseEngine` suite. The test simulates a slow query by mocking `Date.now()` globally inside a `try...finally` block, ensuring it artificially increments past the 100ms timeout configured on the test engine instance. It accurately asserts that the `assert.rejects` catches the specific timeout error message: `Query execution timed out after 100ms`.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: zknpr

tests/unit/sqlite-db.test.ts

@@ -127,4 +127,50 @@ describe('WasmDatabaseEngine', () => {
       assert.strictEqual(countYellow, 1);
     });
   });
+
+  describe('executeQuery', () => {
+    it('should timeout long running queries', async () => {
+      // Create a specific engine instance with a short timeout
+      const result = await createDatabaseEngine({
+        content: null,
+        maxSize: 0,
+        readOnlyMode: false,
+        queryTimeout: 100 // 100ms timeout
+      });
+      const timeoutEngine = result.operations;
+
+      await timeoutEngine.executeQuery("CREATE TABLE timeout_test (id INTEGER PRIMARY KEY, value TEXT)");
+      await timeoutEngine.insertRow('timeout_test', { id: 1, value: 'test1' });
+      await timeoutEngine.insertRow('timeout_test', { id: 2, value: 'test2' });
+
+      const originalDateNow = Date.now;
+      let callCount = 0;
+
+      try {
+        Date.now = () => {
+          // First call establishes startTime, subsequent calls simulate elapsed time
+          if (callCount === 0) {
+            callCount++;
+            return 1000;
+          }
+          callCount++;
+          // Return a time far in the future to trigger timeout
+          return 1000 + 200;
+        };
+
+        // This query will hit the while(stmt.step()) loop
+        await assert.rejects(
+          async () => {
+            await timeoutEngine.executeQuery("SELECT * FROM timeout_test");
+          },
+          (err: any) => {
+            assert.strictEqual(err.message, "Query failed: Query execution timed out after 100ms");
+            return true;
+          }
+        );
+      } finally {
+        Date.now = originalDateNow;
+      }
+    });
+  });
 });