diff --git a/packages/starlight/__tests__/build-format-file/navigation.ts b/packages/starlight/__tests__/build-format-file/navigation.test.ts
similarity index 97%
rename from packages/starlight/__tests__/build-format-file/navigation.ts
rename to packages/starlight/__tests__/build-format-file/navigation.test.ts
index f733049acef..f91e98a355c 100644
--- a/packages/starlight/__tests__/build-format-file/navigation.ts
+++ b/packages/starlight/__tests__/build-format-file/navigation.test.ts
@@ -17,7 +17,7 @@ vi.mock('astro:content', async () =>
 
 describe('getSidebar with build.format = "file"', () => {
 	test('returns an array of sidebar entries with its file extension', () => {
-		expect(getSidebar('/', undefined)).toMatchInlineSnapshot(`
+		expect(getSidebar('/index.html', undefined)).toMatchInlineSnapshot(`
 			[
 			  {
 			    "attrs": {},