test: removed exprimental option warning helper

packages/next/server/config.ts

@@ -126,7 +126,7 @@ function setFontLoaderDefaults(config: NextConfigComplete) {
   } catch {}
 }
 
-function warnOptionHasBeenMovedOutOfExperimental(
+export function warnOptionHasBeenMovedOutOfExperimental(
   config: NextConfig,
   oldKey: string,
   newKey: string,

test/unit/warn-removed-experimental-config.test.ts

@@ -0,0 +1,98 @@
+import { warnOptionHasBeenMovedOutOfExperimental } from 'next/dist/server/config'
+
+describe('warnOptionHasBeenMovedOutOfExperimental', () => {
+  let spy: jest.SpyInstance
+  beforeAll(() => {
+    spy = jest.spyOn(console, 'warn').mockImplementation(() => {})
+  })
+
+  it('should not log warning message without experimental config', () => {
+    warnOptionHasBeenMovedOutOfExperimental(
+      {},
+      'skipTrailingSlashRedirect',
+      'skipTrailingSlashRedirect',
+      'next.config.js'
+    )
+
+    warnOptionHasBeenMovedOutOfExperimental(
+      {
+        experimental: {},
+      },
+      'skipTrailingSlashRedirect',
+      'skipTrailingSlashRedirect',
+      'next.config.js'
+    )
+
+    expect(spy).not.toBeCalled()
+  })
+
+  it('should log warning message with removed experimental config', () => {
+    warnOptionHasBeenMovedOutOfExperimental(
+      {
+        experimental: {
+          skipTrailingSlashRedirect: true,
+        },
+      } as any,
+      'skipTrailingSlashRedirect',
+      'skipTrailingSlashRedirect',
+      'next.config.js'
+    )
+
+    expect(spy).toHaveBeenCalledWith(
+      expect.stringContaining('warn'),
+      '`skipTrailingSlashRedirect` has been moved out of `experimental`. Please update your next.config.js file accordingly.'
+    )
+  })
+
+  it('should log warning message with removed experimental config - complex key', () => {
+    warnOptionHasBeenMovedOutOfExperimental(
+      {
+        experimental: {
+          relay: true,
+        },
+      } as any,
+      'relay',
+      'compiler.relay',
+      'next.config.js'
+    )
+
+    expect(spy).toHaveBeenCalledWith(
+      expect.stringContaining('warn'),
+      '`relay` has been moved out of `experimental` and into `compiler.relay`. Please update your next.config.js file accordingly.'
+    )
+  })
+
+  it('should update removed experimental config into new config', () => {
+    const config = {
+      experimental: {
+        skipTrailingSlashRedirect: true,
+      },
+    } as any
+    warnOptionHasBeenMovedOutOfExperimental(
+      config,
+      'skipTrailingSlashRedirect',
+      'skipTrailingSlashRedirect',
+      'next.config.js'
+    )
+
+    expect(config.experimental.skipTrailingSlashRedirect).toBe(true)
+    expect(config.skipTrailingSlashRedirect).toBe(true)
+  })
+
+  it('should update removed experimental config into new config - complex key', () => {
+    const config = {
+      experimental: {
+        foo: 'bar',
+      },
+    } as any
+    warnOptionHasBeenMovedOutOfExperimental(
+      config,
+      'foo',
+      'deep.prop.baz',
+      'next.config.js'
+    )
+
+    expect(config.experimental.foo).toBe('bar')
+    expect(config.deep.prop.baz).toBe('bar')
+  })
+})