fix: dont hot-swap registered components, #1050

Author: theKashey

Diff for: src/reactHotLoader.js

@@ -9,6 +9,7 @@ import {
   getProxyById,
   createProxyForType,
   isTypeBlacklisted,
+  registerComponent,
 } from './reconciler/proxies'
 import configuration from './configuration'
 import logger from './logger'
@@ -62,6 +63,7 @@ const reactHotLoader = {
       }
 
       updateProxyById(id, type)
+      registerComponent(type)
     }
   },
 

Diff for: src/reconciler/hotReplacementRender.js

@@ -3,6 +3,7 @@ import { PROXY_IS_MOUNTED, PROXY_KEY, UNWRAP_PROXY } from '../proxy'
 import {
   getIdByType,
   getProxyByType,
+  isRegisteredComponent,
   isTypeBlacklisted,
   updateProxyById,
 } from './proxies'
@@ -99,7 +100,7 @@ const equalClasses = (a, b) => {
 }
 
 export const areSwappable = (a, b) => {
-  // both are registered components
+  // both are registered components and have the same name
   if (getIdByType(b) && getIdByType(a) === getIdByType(b)) {
     return true
   }
@@ -401,7 +402,12 @@ const hotReplacementRender = (instance, stack) => {
           throw new Error('React-hot-loader: wrong configuration')
         }
 
-        if (areSwappable(childType, stackChild.type)) {
+        if (
+          isRegisteredComponent(childType) ||
+          isRegisteredComponent(stackChild.type)
+        ) {
+          // one of elements are registered via babel plugin, and should not be handled by hot swap
+        } else if (areSwappable(childType, stackChild.type)) {
           // they are both registered, or have equal code/displayname/signature
 
           // update proxy using internal PROXY_KEY

Diff for: src/reconciler/proxies.js

@@ -3,6 +3,7 @@ import { resetClassProxies } from '../proxy/createClassProxy'
 
 let proxiesByID
 let blackListedProxies
+let registeredComponents
 let idsByType
 
 let elementCount = 0
@@ -16,6 +17,9 @@ export const isProxyType = type => type[PROXY_KEY]
 export const getProxyById = id => proxiesByID[id]
 export const getProxyByType = type => getProxyById(getIdByType(type))
 
+export const registerComponent = type => registeredComponents.set(type, 1)
+export const isRegisteredComponent = type => registeredComponents.has(type)
+
 export const setStandInOptions = options => {
   renderOptions = options
 }
@@ -42,6 +46,7 @@ export const resetProxies = () => {
   proxiesByID = {}
   idsByType = new WeakMap()
   blackListedProxies = new WeakMap()
+  registeredComponents = new WeakMap()
   resetClassProxies()
 }
 

Diff for: test/reconciler.test.js

@@ -157,6 +157,54 @@ describe('reconciler', () => {
       expect(areComponentsEqual(second.Component, third.Component)).toBe(false)
     })
 
+    it('should hot-swap only internal components', () => {
+      let An0
+      let An1
+      let Bn0
+      let Bn1
+      let App
+      {
+        const A = () => <div>A</div>
+        const B = () => <div>A</div>
+        App = () => (
+          <div>
+            <A />
+            <B />
+          </div>
+        )
+        An0 = A
+        Bn0 = B
+        reactHotLoader.register(App, 'App', 'test-hot-swap.js')
+        reactHotLoader.register(B, 'B0', 'test-hot-swap.js')
+      }
+      const wrapper = mount(
+        <div>
+          <App />
+        </div>,
+      )
+      {
+        const A = () => <div>A</div>
+        const B = () => <div>A</div>
+        App = () => (
+          <div>
+            <A />
+            <B />
+          </div>
+        )
+        An1 = A
+        Bn1 = B
+        reactHotLoader.register(App, 'App', 'test-hot-swap.js')
+        reactHotLoader.register(B, 'B1', 'test-hot-swap.js')
+      }
+      incrementGeneration()
+      wrapper.setProps({ update: 'now' })
+
+      // A-s are similar, and got merged
+      expect(<An0 />.type).toEqual(<An1 />.type)
+      // B-s are simlar, but known to be different types - not merged
+      expect(<Bn0 />.type).not.toEqual(<Bn1 />.type)
+    })
+
     it('should regenerate internal component without AppContainer', () => {
       const first = spyComponent(
         ({ children }) => <b>{children}</b>,