fix: load .env file in vitest config and update integration test docs (#26828)

* docs: update integration test commands for Vitest 4.0

Vitest 4.0 no longer supports custom CLI flags like --integrationTestsOnly.
Updated documentation to use the new VITEST_MODE=integration environment
variable syntax instead.

Co-Authored-By: eunjae@cal.com <hey@eunjae.dev>

* fix: load .env file in vitest config for integration tests

Vitest 4.0 doesn't automatically load .env files into process.env.
This caused integration tests to fail with ECONNREFUSED errors because
DATABASE_URL was not available.

Added loadEnv from Vite to load .env file at the start of vitest config.

Co-Authored-By: eunjae@cal.com <hey@eunjae.dev>

* chore: remove unnecessary comment

Co-Authored-By: eunjae@cal.com <hey@eunjae.dev>

* fix: only load .env vars if not already set

Co-Authored-By: eunjae@cal.com <hey@eunjae.dev>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

AGENTS.md

@@ -48,10 +48,10 @@ yarn vitest run path/to/file.test.ts
 yarn vitest run path/to/file.test.ts --testNamePattern="specific test name"
 
 # Integration test specific file
-yarn test path/to/file.integration-test.ts -- --integrationTestsOnly
+VITEST_MODE=integration yarn test path/to/file.integration-test.ts
 
 # Integration test specific file + specific test
-yarn test path/to/file.integration-test.ts --testNamePattern="specific test name" -- --integrationTestsOnly
+VITEST_MODE=integration yarn test path/to/file.integration-test.ts --testNamePattern="specific test name"
 
 # E2E test specific file
 PLAYWRIGHT_HEADLESS=1 yarn e2e path/to/file.e2e.ts

agents/commands.md

@@ -34,9 +34,9 @@
 
 ### Integration Tests
 
-- `yarn test -- --integrationTestsOnly` - Run integration tests (vitest)
+- `VITEST_MODE=integration yarn test` - Run integration tests (vitest)
-- `yarn test <filename> -- --integrationTestsOnly` - Run integration tests for specific file
+- `VITEST_MODE=integration yarn test <filename>` - Run integration tests for specific file
-- `yarn test <filename> -t "<testName>" -- --integrationTestsOnly` - Run specific integration test by name for specific file
+- `VITEST_MODE=integration yarn test <filename> -t "<testName>"` - Run specific integration test by name for specific file
 
 
 ### End-to-End Tests
@@ -73,7 +73,7 @@
 yarn vitest run packages/lib/some-file.test.ts
 
 # Integration test specific file
-yarn test routing-form-response-denormalized.integration-test.ts -- --integrationTestsOnly
+VITEST_MODE=integration yarn test routing-form-response-denormalized.integration-test.ts
 
 # E2E test specific file
 yarn e2e tests/booking-flow.e2e.ts

vitest.config.mts

@@ -1,7 +1,15 @@
 import path from "node:path";
 import react from "@vitejs/plugin-react";
+import { loadEnv } from "vite";
 import { defineConfig } from "vitest/config";
 
+const env = loadEnv("", process.cwd(), "");
+for (const [key, value] of Object.entries(env)) {
+  if (process.env[key] === undefined) {
+    process.env[key] = value;
+  }
+}
+
 const vitestMode = process.env.VITEST_MODE;
 // Support both new VITEST_MODE env var and legacy CLI flags for backwards compatibility
 // The CLI flags are passed through but Vitest 4.0 doesn't reject them when using yarn test