fix(dev): bind plugin context functions (#14569)

Co-authored-by: Bjorn Lu <bjornlu.dev@gmail.com>
Co-authored-by: 翠 / green <green@sapphi.red>

packages/vite/src/node/server/__tests__/pluginContainer.spec.ts

@@ -10,6 +10,38 @@ let resolveId: (id: string) => any
 let moduleGraph: ModuleGraph
 
 describe('plugin container', () => {
+  it('has bound methods', async () => {
+    expect.assertions(14)
+    const entryUrl = '/x.js'
+
+    const plugin: Plugin = {
+      name: 'p1',
+      load(id) {
+        // bound functions and bound arrow functions do not have prototype
+        expect(this.parse.prototype).equals(undefined)
+        expect(this.resolve.prototype).equals(undefined)
+        expect(this.load.prototype).equals(undefined)
+        expect(this.getModuleInfo.prototype).equals(undefined)
+        expect(this.getModuleIds.prototype).equals(undefined)
+        expect(this.addWatchFile.prototype).equals(undefined)
+        expect(this.getWatchFiles.prototype).equals(undefined)
+        expect(this.emitFile.prototype).equals(undefined)
+        expect(this.setAssetSource.prototype).equals(undefined)
+        expect(this.getFileName.prototype).equals(undefined)
+        expect(this.warn.prototype).equals(undefined)
+        expect(this.error.prototype).equals(undefined)
+        expect(this.debug.prototype).equals(undefined)
+        expect(this.info.prototype).equals(undefined)
+      },
+    }
+
+    const container = await getPluginContainer({
+      plugins: [plugin],
+    })
+
+    await container.load(entryUrl)
+  })
+
   describe('getModuleInfo', () => {
     beforeEach(() => {
       moduleGraph = new ModuleGraph((id) => resolveId(id))

packages/vite/src/node/server/pluginContainer.ts

@@ -299,6 +299,20 @@ export async function createPluginContainer(
 
     constructor(initialPlugin?: Plugin) {
       this._activePlugin = initialPlugin || null
+      this.parse = this.parse.bind(this)
+      this.resolve = this.resolve.bind(this)
+      this.load = this.load.bind(this)
+      this.getModuleInfo = this.getModuleInfo.bind(this)
+      this.getModuleIds = this.getModuleIds.bind(this)
+      this.addWatchFile = this.addWatchFile.bind(this)
+      this.getWatchFiles = this.getWatchFiles.bind(this)
+      this.emitFile = this.emitFile.bind(this)
+      this.setAssetSource = this.setAssetSource.bind(this)
+      this.getFileName = this.getFileName.bind(this)
+      this.warn = this.warn.bind(this)
+      this.error = this.error.bind(this)
+      this.debug = this.debug.bind(this)
+      this.info = this.info.bind(this)
     }
 
     parse(code: string, opts: any) {