fix(testing): make ModelStatsDisplay snapshot test deterministic (#5236)

Co-authored-by: Jacob Richman <[email protected]>

1 files changed, 14 insertions, 1 deletions

diff --git a/packages/cli/src/ui/components/ModelStatsDisplay.test.tsx b/packages/cli/src/ui/components/ModelStatsDisplay.test.tsx
index 57382d91..6adf2652 100644
--- a/packages/cli/src/ui/components/ModelStatsDisplay.test.tsx
+++ b/packages/cli/src/ui/components/ModelStatsDisplay.test.tsx
@@ -5,7 +5,7 @@
  */
 
 import { render } from 'ink-testing-library';
-import { describe, it, expect, vi } from 'vitest';
+import { describe, it, expect, vi, beforeAll, afterAll } from 'vitest';
 import { ModelStatsDisplay } from './ModelStatsDisplay.js';
 import * as SessionContext from '../contexts/SessionContext.js';
 import { SessionMetrics } from '../contexts/SessionContext.js';
@@ -38,6 +38,19 @@ const renderWithMockedStats = (metrics: SessionMetrics) => {
 };
 
 describe('<ModelStatsDisplay />', () => {
+  beforeAll(() => {
+    vi.spyOn(Number.prototype, 'toLocaleString').mockImplementation(function (
+      this: number,
+    ) {
+      // Use a stable 'en-US' format for test consistency.
+      return new Intl.NumberFormat('en-US').format(this);
+    });
+  });
+
+  afterAll(() => {
+    vi.restoreAllMocks();
+  });
+
   it('should render "no API calls" message when there are no active models', () => {
     const { lastFrame } = renderWithMockedStats({
       models: {},