chore: improve BaseTransition (#4811)

packages/runtime-core/src/components/BaseTransition.ts

@@ -161,7 +161,11 @@ const BaseTransitionImpl: ComponentOptions = {
       const rawProps = toRaw(props)
       const { mode } = rawProps
       // check mode
-      if (__DEV__ && mode && !['in-out', 'out-in', 'default'].includes(mode)) {
+      if (
+        __DEV__ &&
+        mode &&
+        mode !== 'in-out' && mode !== 'out-in' && mode !== 'default'
+      ) {
         warn(`invalid <transition> mode: ${mode}`)
       }
 

packages/vue/__tests__/Transition.spec.ts

@@ -1969,6 +1969,21 @@ describe('e2e: Transition', () => {
     ).toHaveBeenWarned()
   })
 
+  test('warn when invalid transition mode', () => {
+    createApp({
+      template: `
+        <div id="container">
+          <transition name="test" mode="none">
+            <div class="test">content</div>
+          </transition>
+        </div>
+      `
+    }).mount(document.createElement('div'))
+    expect(
+      `invalid <transition> mode: none`
+    ).toHaveBeenWarned()
+  })
+
   // #3227
   test(`HOC w/ merged hooks`, async () => {
     const innerSpy = jest.fn()