feat: add isEntry flag to resolveId hook

src/esbuild/index.ts

@@ -94,7 +94,14 @@ export function getEsbuildPlugin <UserOptions = {}> (
 
           if (plugin.resolveId) {
             onResolve({ filter: onResolveFilter }, async (args) => {
-              const result = await plugin.resolveId!(args.path, args.importer)
+              const isEntry = args.kind === 'entry-point'
+              const result = await plugin.resolveId!(
+                args.path,
+                // We explicitly have this if statement here for consistency with the integration of other bundelers.
+                // Here, `args.importer` is just an empty string on entry files whereas the euqivalent on other bundlers is `undefined.`
+                isEntry ? undefined : args.importer,
+                { isEntry }
+              )
               if (typeof result === 'string') {
                 return { path: result, namespace: plugin.name }
               } else if (typeof result === 'object' && result !== null) {

src/types.ts

@@ -32,7 +32,7 @@ export interface UnpluginOptions {
   transformInclude?: (id: string) => boolean;
   transform?: (this: UnpluginBuildContext & UnpluginContext, code: string, id: string) => Thenable<TransformResult>;
   load?: (this: UnpluginBuildContext & UnpluginContext, id: string) => Thenable<TransformResult>
-  resolveId?: (id: string, importer?: string) => Thenable<string | ExternalIdResult | null | undefined>
+  resolveId?: (id: string, importer: string | undefined, options: { isEntry: boolean }) => Thenable<string | ExternalIdResult | null | undefined>
   watchChange?: (this: UnpluginBuildContext, id: string, change: {event: 'create' | 'update' | 'delete'}) => void
 
   // framework specify extends

src/webpack/index.ts

@@ -2,7 +2,7 @@ import fs from 'fs'
 import { fileURLToPath } from 'url'
 import { resolve, dirname } from 'path'
 import VirtualModulesPlugin from 'webpack-virtual-modules'
-import type { Resolver, ResolveRequest } from 'enhanced-resolve'
+import type { ResolvePluginInstance } from 'webpack'
 import type { UnpluginContextMeta, UnpluginInstance, UnpluginFactory, WebpackCompiler, ResolvedUnpluginOptions } from '../types'
 import { slash, backSlash } from './utils'
 import { createContext } from './context'
@@ -79,58 +79,63 @@ export function getWebpackPlugin<UserOptions = {}> (
           plugin.__vfsModules = new Set()
           plugin.__vfs = vfs
 
-          const resolver = {
-            apply (resolver: Resolver) {
+          const resolverPlugin: ResolvePluginInstance = {
+            apply (resolver) {
               const target = resolver.ensureHook('resolve')
-              const tap = () => async (request: ResolveRequest, resolveContext: any, callback: any) => {
-                if (!request.request) {
-                  return callback()
-                }
-
-                const id = backSlash(request.request)
-
-                // filter out invalid requests
-                if (id.startsWith(plugin.__virtualModulePrefix)) {
-                  return callback()
-                }
-
-                // call hook
-                const result = await plugin.resolveId!(slash(id))
-                if (result == null) {
-                  return callback()
-                }
-                let resolved = typeof result === 'string' ? result : result.id
-
-                // TODO: support external
-                // const isExternal = typeof result === 'string' ? false : result.external === true
-
-                // if the resolved module is not exists,
-                // we treat it as a virtual module
-                if (!fs.existsSync(resolved)) {
-                  resolved = plugin.__virtualModulePrefix + backSlash(resolved)
-                  // webpack virtual module should pass in the correct path
-                  plugin.__vfs!.writeModule(resolved, '')
-                  plugin.__vfsModules!.add(resolved)
-                }
-
-                // construct the new request
-                const newRequest = {
-                  ...request,
-                  request: resolved
-                }
-
-                // redirect the resolver
-                resolver.doResolve(target, newRequest, null, resolveContext, callback)
-              }
 
               resolver
                 .getHook('resolve')
-                .tapAsync('unplugin', tap())
+                .tapAsync(plugin.name, async (request, resolveContext, callback) => {
+                  if (!request.request) {
+                    return callback()
+                  }
+
+                  const id = backSlash(request.request)
+
+                  // filter out invalid requests
+                  if (id.startsWith(plugin.__virtualModulePrefix)) {
+                    return callback()
+                  }
+
+                  const requestContext = (request as unknown as { context: { issuer: string } }).context
+                  const importer = requestContext.issuer !== '' ? requestContext.issuer : undefined
+                  const isEntry = requestContext.issuer === ''
+
+                  // call hook
+                  const result = await plugin.resolveId!(slash(id), importer, { isEntry })
+
+                  if (result == null) {
+                    return callback()
+                  }
+
+                  let resolved = typeof result === 'string' ? result : result.id
+
+                  // TODO: support external
+                  // const isExternal = typeof result === 'string' ? false : result.external === true
+
+                  // If the resolved module does not exist,
+                  // we treat it as a virtual module
+                  if (!fs.existsSync(resolved)) {
+                    resolved = plugin.__virtualModulePrefix + backSlash(resolved)
+                    // webpack virtual module should pass in the correct path
+                    plugin.__vfs!.writeModule(resolved, '')
+                    plugin.__vfsModules!.add(resolved)
+                  }
+
+                  // construct the new request
+                  const newRequest = {
+                    ...request,
+                    request: resolved
+                  }
+
+                  // redirect the resolver
+                  resolver.doResolve(target, newRequest, null, resolveContext, callback)
+                })
             }
           }
 
           compiler.options.resolve.plugins = compiler.options.resolve.plugins || []
-          compiler.options.resolve.plugins.push(resolver)
+          compiler.options.resolve.plugins.push(resolverPlugin)
         }
 
         // load hook

test/unit-tests/resolve-id/resolve-id.test.ts

@@ -0,0 +1,111 @@
+import * as path from 'path'
+import { it, describe, expect, vi, afterEach, Mock } from 'vitest'
+import * as vite from 'vite'
+import * as rollup from 'rollup'
+import { webpack } from 'webpack'
+import * as esbuild from 'esbuild'
+import { createUnplugin, UnpluginOptions } from '../../../src'
+
+function createUnpluginWithCallback (resolveIdCallback: UnpluginOptions['resolveId']) {
+  return createUnplugin(() => ({
+    name: 'test-plugin',
+    resolveId: resolveIdCallback
+  }))
+}
+
+// We extract this check because all bundlers should behave the same
+function checkResolveIdHook (resolveIdCallback: Mock): void {
+  expect.assertions(4)
+
+  expect(resolveIdCallback).toHaveBeenCalledWith(
+    expect.stringMatching(/(?:\/|\\)entry\.js$/),
+    undefined,
+    expect.objectContaining({ isEntry: true })
+  )
+
+  expect(resolveIdCallback).toHaveBeenCalledWith(
+    './proxy-export',
+    expect.stringMatching(/(?:\/|\\)entry\.js$/),
+    expect.objectContaining({ isEntry: false })
+  )
+
+  expect(resolveIdCallback).toHaveBeenCalledWith(
+    './default-export',
+    expect.stringMatching(/(?:\/|\\)proxy-export\.js$/),
+    expect.objectContaining({ isEntry: false })
+  )
+
+  expect(resolveIdCallback).toHaveBeenCalledWith(
+    './named-export',
+    expect.stringMatching(/(?:\/|\\)proxy-export\.js$/),
+    expect.objectContaining({ isEntry: false })
+  )
+}
+
+describe('resolveId hook', () => {
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
+  it('vite', async () => {
+    const mockResolveIdHook = vi.fn(() => undefined)
+    const plugin = createUnpluginWithCallback(mockResolveIdHook).vite
+
+    await vite.build({
+      clearScreen: false,
+      plugins: [{ ...plugin(), enforce: 'pre' }], // we need to define `enforce` here for the plugin to be run
+      build: {
+        lib: {
+          entry: path.resolve(__dirname, 'test-src/entry.js'),
+          name: 'TestLib'
+        },
+        write: false // don't output anything
+      }
+    })
+
+    checkResolveIdHook(mockResolveIdHook)
+  })
+
+  it('rollup', async () => {
+    const mockResolveIdHook = vi.fn(() => undefined)
+    const plugin = createUnpluginWithCallback(mockResolveIdHook).rollup
+
+    await rollup.rollup({
+      input: path.resolve(__dirname, 'test-src/entry.js'),
+      plugins: [plugin()]
+    })
+
+    checkResolveIdHook(mockResolveIdHook)
+  })
+
+  it('webpack', async () => {
+    const mockResolveIdHook = vi.fn(() => undefined)
+    const plugin = createUnpluginWithCallback(mockResolveIdHook).webpack
+
+    await new Promise((resolve) => {
+      webpack(
+        {
+          entry: path.resolve(__dirname, 'test-src/entry.js'),
+          plugins: [plugin()]
+        },
+        resolve
+      )
+    })
+
+    checkResolveIdHook(mockResolveIdHook)
+  })
+
+  it('esbuild', async () => {
+    const mockResolveIdHook = vi.fn(() => undefined)
+    const plugin = createUnpluginWithCallback(mockResolveIdHook).esbuild
+
+    await esbuild.build({
+      entryPoints: [path.resolve(__dirname, 'test-src/entry.js')],
+      plugins: [plugin()],
+      bundle: true, // actually traverse imports
+      write: false // don't pollute console
+    })
+
+    checkResolveIdHook(mockResolveIdHook)
+  })
+})

test/unit-tests/resolve-id/test-src/default-export.js

@@ -0,0 +1 @@
+export default 'some string'

test/unit-tests/resolve-id/test-src/entry.js

@@ -0,0 +1,3 @@
+import { named, proxiedDefault } from './proxy-export'
+
+process.stdout.write(JSON.stringify({ named, proxiedDefault }))

test/unit-tests/resolve-id/test-src/named-export.js

@@ -0,0 +1 @@
+export const named = 'named export'

test/unit-tests/resolve-id/test-src/proxy-export.js

@@ -0,0 +1,2 @@
+export { named } from './named-export'
+export { default as proxiedDefault } from './default-export'