NODE_ENV is set to undefined before running a test command (#6823)

test/integration/production-build-dir/test/index.test.js

@@ -16,7 +16,6 @@ describe('Production Custom Build Directory', () => {
     it('should render the page', async () => {
       const result = await runNextCommand(['build', 'build'], {
         cwd: join(__dirname, '..'),
-        spawnOptions: { env: { ...process.env, NODE_ENV: 'production' } },
         stdout: true,
         stderr: true
       })

test/integration/production-config/test/index.test.js

@@ -41,27 +41,21 @@ describe('Production Config Usage', () => {
 
   describe('env', () => {
     it('should fail with __ in env key', async () => {
-      const result = await runNextCommand(['build', appDir], { spawnOptions: {
-        env: {
-          ...process.env,
-          ENABLE_ENV_FAIL_UNDERSCORE: true
-        }
-      },
-      stdout: true,
-      stderr: true })
+      const result = await runNextCommand(['build', appDir], {
+        env: { ENABLE_ENV_FAIL_UNDERSCORE: true },
+        stdout: true,
+        stderr: true
+      })
 
       expect(result.stderr).toMatch(/The key "__NEXT_MY_VAR" under/)
     })
 
     it('should fail with NODE_ in env key', async () => {
-      const result = await runNextCommand(['build', appDir], { spawnOptions: {
-        env: {
-          ...process.env,
-          ENABLE_ENV_FAIL_NODE: true
-        }
-      },
-      stdout: true,
-      stderr: true })
+      const result = await runNextCommand(['build', appDir], {
+        env: { ENABLE_ENV_FAIL_NODE: true },
+        stdout: true,
+        stderr: true
+      })
 
       expect(result.stderr).toMatch(/The key "NODE_ENV" under/)
     })

test/integration/production/test/index.test.js

@@ -27,9 +27,8 @@ const context = {}
 
 describe('Production Usage', () => {
   beforeAll(async () => {
-    await runNextCommand(['build', appDir], {
-      spawnOptions: { env: { ...process.env, NODE_ENV: 'production' } }
-    })
+    await runNextCommand(['build', appDir])
+
     app = nextServer({
       dir: join(__dirname, '../'),
       dev: false,

test/lib/next-test-utils.js

@@ -74,9 +74,12 @@ export function runNextCommand (argv, options = {}) {
   const nextDir = path.dirname(require.resolve('next/package'))
   const nextBin = path.join(nextDir, 'dist/bin/next')
   const cwd = options.cwd || nextDir
+  // Let Next.js decide the environment
+  const env = { ...process.env, ...options.env, NODE_ENV: undefined }
+
   return new Promise((resolve, reject) => {
     console.log(`Running command "next ${argv.join(' ')}"`)
-    const instance = spawn('node', [nextBin, ...argv], { ...options.spawnOptions, cwd, stdio: ['ignore', 'pipe', 'pipe'] })
+    const instance = spawn('node', [nextBin, ...argv], { ...options.spawnOptions, cwd, env, stdio: ['ignore', 'pipe', 'pipe'] })
 
     if (typeof options.instance === 'function') {
       options.instance(instance)