add support for custom resolvers

CHANGELOG.md

@@ -1,7 +1,8 @@
 # changelog
 
  * 2.5.3 _Oct.12.2023_
-   * [update resolver](https://github.com/iambumblehead/esmock/pull/243) to latest version, slightly faster with fewer loops
+   * [update resolver](https://github.com/iambumblehead/esmock/pull/250) to latest version, slightly faster with fewer loops
+   * [add support for resolver](https://github.com/iambumblehead/esmock/pull/251) configuration option
  * 2.5.2 _Oct.06.2023_
    * [update resolver](https://github.com/iambumblehead/esmock/pull/243) to improve module resolution. See resolvewithplus tags [v2.0.6](https://github.com/iambumblehead/resolvewithplus/releases/tag/v2.0.6) and [v2.0.7.](https://github.com/iambumblehead/resolvewithplus/releases/tag/v2.0.7)
    * **resolve "exports" before "main".** The [spec says:](https://nodejs.org/api/packages.html#package-entry-points) _the "exports" field takes precedence over "main" in supported versions of Node.js._ The updated resolver correctly returns "main" before "exports" (older resolver did not).

package.json

@@ -1,7 +1,7 @@
 {
   "name": "esmock",
   "type": "module",
-  "version": "2.5.2",
+  "version": "2.5.3",
   "license": "ISC",
   "readmeFilename": "README.md",
   "description": "provides native ESM import and globals mocking for unit tests",

src/esmock.d.ts

@@ -1,9 +1,11 @@
 type MockMap = { [specifier: string]: any }
+type Resolver = (id: string, parent: string) => string | null
 
 type Options = {
   strict?: boolean | undefined,
   purge?: boolean | undefined,
-  isModuleNotFoundError?: boolean | undefined
+  isModuleNotFoundError?: boolean | undefined,
+  resolver?: Resolver | undefined
 }
 
 type MockFunction = {
@@ -90,5 +92,6 @@ export {
   strictest,
   type MockFunction,
   type MockMap,
-  type Options
+  type Options,
+  type Resolver   
 }

src/esmockArgs.js

@@ -1,3 +1,5 @@
+import resolver from 'resolvewithplus'
+
 // extracts path or fileurl from stack,
 // '  at <anonymous> (/root/test.js:11:31)' -> /root/test.js
 // '  at Object.handler (file:///D:/a/test.js:11:31)' -> file:///D:/a/test.js
@@ -17,7 +19,7 @@ export default (arg, optsextra) => {
     (new Error).stack.split('\n')[3].replace(stackpathre, '$2'),
     ...arg.slice(1)
   ]
-  arg[4] = {...arg[4], ...optsextra}
+  arg[4] = { resolver, ...arg[4], ...optsextra}
 
   return arg
 }

src/esmockModule.js

@@ -17,6 +17,9 @@ const isDirPathRe = /^\.?\.?([a-zA-Z]:)?(\/|\\)/
 const nextId = ((id = 0) => () => ++id)()
 const objProto = Object.getPrototypeOf({})
 const isPlainObj = o => Object.getPrototypeOf(o) === objProto
+const iscoremodule = resolvewith.iscoremodule
+const protocolNodeRe = /^node:/
+const addprotocolnode = p => protocolNodeRe.test(p) ? p : `node:${p}`
 
 // assigning the object to its own prototypal inheritor can error, eg
 //   'Cannot assign to read only property \'F_OK\' of object \'#<Object>\''
@@ -46,7 +49,7 @@ const esmockModuleApply = (defLive, def, fileURL) => {
 
   // if safe, an extra "default.default" is added for compatibility with
   // babel-generated dist cjs files which also define "default.default"
-  if (!resolvewith.iscoremodule(fileURL) && Object.isExtensible(def.default))
+  if (!iscoremodule(fileURL) && Object.isExtensible(def.default))
     def.default.default = def.default
 
   return def
@@ -59,7 +62,7 @@ const esmockModuleIsESM = (fileURL, isesm) => {
   if (typeof isesm === 'boolean')
     return isesm
 
-  isesm = !resolvewith.iscoremodule(fileURL)
+  isesm = !iscoremodule(fileURL)
     && isDirPathRe.test(fileURL)
     && esmockIsESMRe.test(fs.readFileSync(fileURL, 'utf-8'))
 
@@ -108,14 +111,17 @@ const esmockModuleCreate = async (treeid, def, id, fileURL, opt) => {
   return mockModuleKey
 }
 
+const esmockResolve = (id, parent, opt) => (
+  iscoremodule(id) ? addprotocolnode(id) : opt.resolver(id, parent))
+
 const esmockModuleId = async (parent, treeid, defs, ids, opt, mocks, id) => {
   ids = ids || Object.keys(defs)
   id = ids[0]
   mocks = mocks || []
 
   if (!id) return mocks
 
-  const fileURL = resolvewith(id, parent)
+  const fileURL = esmockResolve(id, parent, opt)
   if (!fileURL && opt.isModuleNotFoundError !== false && id !== 'import')
     throw esmockErr.errModuleIdNotFound(id, parent)
 
@@ -125,7 +131,7 @@ const esmockModuleId = async (parent, treeid, defs, ids, opt, mocks, id) => {
 }
 
 const esmockModule = async (moduleId, parent, defs, gdefs, opt) => {
-  const moduleFileURL = resolvewith(moduleId, parent)
+  const moduleFileURL = esmockResolve(moduleId, parent, opt)
   if (!moduleFileURL)
     throw esmockErr.errModuleIdNotFound(moduleId, parent)
 

tests/local/customResolverChild.js

@@ -0,0 +1,7 @@
+const isMocked = false
+const isCustomResolverChild = true
+
+export default {
+  isCustomResolverChild,
+  isMocked
+}

tests/local/customResolverParent.js

@@ -0,0 +1,9 @@
+import child from 'RESOLVECUSTOM'
+import path from 'node:path'
+
+const pathbasenameresult = path.basename('/the/very/happy-dog.png')
+
+export {
+  child,
+  pathbasenameresult
+}

tests/tests-node/esmock.node.resolver-custom.test.js

@@ -0,0 +1,66 @@
+import test from 'node:test'
+import assert from 'node:assert/strict'
+import module from 'node:module'
+import esmock from 'esmock'
+
+function resolverCustom (moduleId, parent) {
+  parent = parent.replace(/\/tests\/.*$/, '/tests/tests-node/')
+
+  // This logic looks unusual because of constraints here. This function must:
+  //  * must work at windows, where path.join and path.resolve cause issues
+  //  * must be string-serializable, no external funcions
+  //  * must resolve these moduleIds to corresponding, existing filepaths
+  //    * '../local/customResolverParent.js',
+  //    * 'RESOLVECUSTOM/
+  return (
+    /RESOLVECUSTOM$/.test(moduleId)
+      ? parent + '../local/customResolverChild.js'
+      : parent + moduleId
+  ).replace(/\/tests-node\/\.\./, '')
+}
+
+async function resolve (specifier, context, next) {
+  return next(
+    specifier === 'RESOLVECUSTOM'
+      ? resolverCustom(specifier, context.parentURL)
+      : specifier, context)
+}
+
+module.register && module.register(`
+data:text/javascript,
+${encodeURIComponent(resolverCustom)}
+export ${encodeURIComponent(resolve)}`.slice(1))
+
+test('should use custom resolver', async () => {
+  if (!module.register)
+    return assert.ok('skip test')
+
+  const customResolverParent = await esmock(
+    '../local/customResolverParent.js', {}, {
+      RESOLVECUSTOM: ({ isMocked: true })
+    }, {
+      resolver: resolverCustom
+    })
+
+  assert.ok(customResolverParent.child.isCustomResolverChild)
+  assert.ok(customResolverParent.child.isMocked)
+})
+
+test('should not call custom resover with builtin moduleIds', async () => {
+  if (!module.register)
+    return assert.ok('skip test')
+
+  const customResolverParent = await esmock(
+    '../local/customResolverParent.js', {}, {
+      RESOLVECUSTOM: ({ isMocked: true }),
+      path: { basename: () => 'basenametest' }
+    }, {
+      resolver: resolverCustom
+    })
+
+  assert.ok(customResolverParent.child.isCustomResolverChild)
+  assert.ok(customResolverParent.child.isMocked)
+  assert.strictEqual(
+    customResolverParent.pathbasenameresult,
+    'basenametest')
+})