Rename test.

evals/frugalReads.eval.ts

@@ -0,0 +1,81 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect } from 'vitest';
+import { evalTest } from './test-helper.js';
+import { READ_FILE_TOOL_NAME } from '@google/gemini-cli-core';
+
+describe('Frugal reads eval', () => {
+  /**
+   * Ensures that the agent is frugal in its use of context by relying
+   * primarily on ranged reads when the line number is known. Smaller
+   * context generally helps the agent to work more reliably for longer.
+   */
+  evalTest('ALWAYS_PASSES', {
+    name: 'should use ranged read when specific line is targeted',
+    files: {
+      'linter_mess.ts': (() => {
+        const lines = [];
+        for (let i = 0; i < 4000; i++) {
+          if (i === 3000) {
+            lines.push(`var oldVar${i} = "needs fix";`);
+          } else {
+            lines.push(`const goodVar${i} = "clean";`);
+          }
+        }
+        return lines.join('\n');
+      })(),
+    },
+    prompt:
+      'Fix the linter error on line 3000 of linter_mess.ts. The error is the use of "var".',
+    assert: async (rig, result) => {
+      const logs = rig.readToolLogs();
+
+      // Check if the agent read the whole file
+      const readCalls = logs.filter(
+        (log) => log.toolRequest?.name === READ_FILE_TOOL_NAME,
+      );
+      expect(
+        readCalls.length,
+        'Agent should have used read_file to check context',
+      ).toBeGreaterThan(0);
+
+      let targetedReadFound = false;
+      let totalLinesRead = 0;
+
+      for (const call of readCalls) {
+        const args = JSON.parse(call.toolRequest.args);
+        if (args.file_path.includes('linter_mess.ts')) {
+          totalLinesRead += args.limit ?? 4000;
+
+          expect(
+            args.limit,
+            'Agent read the entire file (missing limit) instead of using ranged read',
+          ).toBeDefined();
+
+          expect(args.limit, 'Agent read too many lines at once').toBeLessThan(
+            1000,
+          );
+
+          if (args.offset !== undefined && args.offset > 2000) {
+            targetedReadFound = true;
+          }
+        }
+      }
+
+      // Ranged read shoud be frugal and just enough to satisfy the task at hand.
+      expect(
+        totalLinesRead,
+        'Agent read more of the file than expected',
+      ).toBeLessThan(500);
+
+      expect(
+        targetedReadFound,
+        'Agent should have used offset to read around line 3000 at least once',
+      ).toBe(true);
+    },
+  });
+});