add import json tests

.eslintrc.json

@@ -1,6 +1,6 @@
 {
   "plugins": [],
-  "ignorePatterns": ["dist"],
+  "ignorePatterns": ["importsJSONfile.js"],
   "extends": [
     "eslint:recommended",
     "plugin:markdown/recommended"    

CHANGELOG.md

@@ -2,6 +2,7 @@
 
  * 2.5.9 _Nov.11.2023_
    * [mock Array-type default export,](https://github.com/iambumblehead/esmock/pull/266) thanks @altearius
+   * [support json import mocking,](https://github.com/iambumblehead/esmock/pull/247) only working at node v21, see [node#49724](https://github.com/nodejs/node/issues/49724)
  * 2.5.8 _Oct.23.2023_
    * [catch yarn PnP exceptions](https://github.com/iambumblehead/esmock/pull/262) @koshic
  * 2.5.7 _Oct.20.2023_

src/esmockCache.js

@@ -8,6 +8,13 @@ const esmockCache = {
   mockDefs: {}
 }
 
+const esmockModuleIdSourceSet = (keysource, source) => (
+  esmockPostMessage({ keysource, source }),
+  global.mockKeysSource[String(keysource)] = source)
+
+const esmockModuleIdSourceGet = keysource => (
+  global.mockKeysSource[String(keysource)])
+
 const esmockTreeIdSet = (key, keylong) => (
   esmockPostMessage({ key, keylong }),
   global.mockKeys[String(key)] = keylong)
@@ -31,7 +38,8 @@ Object.assign(global, {
   esmockCache,
   esmockCacheGet,
   esmockTreeIdGet,
-  mockKeys: global.mockKeys || {}
+  mockKeys: global.mockKeys || {},
+  mockKeysSource: global.mockKeysSource || {}
 })
 
 export {
@@ -40,6 +48,8 @@ export {
   esmockCacheGet,
   esmockTreeIdSet,
   esmockTreeIdGet,
+  esmockModuleIdSourceSet,
+  esmockModuleIdSourceGet,
   esmockCacheResolvedPathIsESMGet,
   esmockCacheResolvedPathIsESMSet
 }

src/esmockLoader.js

@@ -31,11 +31,14 @@ const moduleIdReCreate = (moduleid, treeid) => new RegExp(
 
 // node v12.0-v18.x, global
 const mockKeys = global.mockKeys = (global.mockKeys || {})
+const mockKeysSource = global.mockKeysSource = (global.mockKeysSource || {})
 
 // node v20.0-v20.6
 const globalPreload = !module.register && (({ port }) => (
   port.addEventListener('message', ev => (
-    mockKeys[ev.data.key] = ev.data.keylong)),
+    ev.data.keysource
+      ? mockKeysSource[ev.data.keysource] = ev.data.source
+      : mockKeys[ev.data.key] = ev.data.keylong)),
   port.unref(),
   'global.postMessageEsmk = d => port.postMessage(d)'
 ))
@@ -44,7 +47,9 @@ const globalPreload = !module.register && (({ port }) => (
 const initialize = module.register && (data => {
   if (data && data.port) {
     data.port.on('message', msg => {
-      mockKeys[msg.key] = msg.keylong
+      msg.keysource
+        ? mockKeysSource[msg.keysource] = msg.source
+        : mockKeys[msg.key] = msg.keylong
     })
   }
 })
@@ -198,6 +203,16 @@ const load = async (url, context, nextLoad) => {
     .split(',')
 
   if (exportedNames && exportedNames[0]) {
+    if (mockKeysSource[url]) {
+      return {
+        // ...await nextLoad(url, context),
+        format: 'json',
+        shortCircuit: true,
+        responseURL: encodeURI(url),
+        source: mockKeysSource[url]
+      }
+    }
+
     return {
       format: 'module',
       shortCircuit: true,

src/esmockModule.js

@@ -1,4 +1,5 @@
 import fs from 'fs'
+import url from 'url'
 import resolvewith from 'resolvewithplus'
 import esmockErr from './esmockErr.js'
 import esmockIsESMRe from './esmockIsESMRe.js'
@@ -7,6 +8,7 @@ import {
   esmockTreeIdSet,
   esmockTreeIdGet,
   esmockCacheSet,
+  esmockModuleIdSourceSet,
   esmockCacheResolvedPathIsESMGet,
   esmockCacheResolvedPathIsESMSet
 } from './esmockCache.js'
@@ -18,6 +20,7 @@ const nextId = ((id = 0) => () => ++id)()
 const objProto = Object.getPrototypeOf({})
 const isPlainObj = o => Object.getPrototypeOf(o) === objProto
 const iscoremodule = resolvewith.iscoremodule
+const isJSONExtnRe = /\.json$/i
 
 // assigning the object to its own prototypal inheritor can error, eg
 //   'Cannot assign to read only property \'F_OK\' of object \'#<Object>\''
@@ -36,7 +39,7 @@ const esmockModuleMergeDefault = (defLive, def) =>
 
 const esmockModuleApply = (defLive, def, fileURL) => {
   // no fileURL here indicates 'import' mock, 'default' not needed
-  if (fileURL === null)
+  if (fileURL === null || isJSONExtnRe.test(fileURL))
     return Object.assign({}, defLive || {}, def)
 
   if (Array.isArray(def))
@@ -95,9 +98,13 @@ const esmockModuleImportedPurge = treeid => {
   String(url.split('esmkgdefs=')[1]).split('#-#').forEach(purgeKey)
 }
 
+const esmockImport = async fileURL => isJSONExtnRe.test(fileURL)
+  ? JSON.parse(fs.readFileSync(new url.URL(fileURL), 'utf-8'))
+  : import(fileURL)
+
 const esmockModuleCreate = async (treeid, def, id, fileURL, opt) => {
   def = esmockModuleApply(
-    opt.strict || !fileURL || await import(fileURL), def, fileURL)
+    opt.strict || !fileURL || await esmockImport(fileURL), def, fileURL)
 
   const mockModuleKey = (fileURL || 'file:///' + id) + '?' + [
     'esmkTreeId=' + treeid,
@@ -107,6 +114,10 @@ const esmockModuleCreate = async (treeid, def, id, fileURL, opt) => {
     'exportNames=' + Object.keys(def).sort().join()
   ].join('&')
 
+  if (isJSONExtnRe.test(fileURL)) {
+    esmockModuleIdSourceSet(mockModuleKey, JSON.stringify(def))
+  }
+
   esmockCacheSet(mockModuleKey, def)
 
   return mockModuleKey

tests/local/example.json

@@ -0,0 +1 @@
+{ "example": "json" }

tests/local/importsJSONfile.js

@@ -0,0 +1,5 @@
+import JSONobj from './example.json' assert { type: 'json' };
+
+export {
+  JSONobj
+}

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

@@ -548,3 +548,36 @@ test('should mock an exported array', async () => {
 
   assert.deepStrictEqual(importsArray(), ['mocked'])
 })
+
+test('should mock imported json', async () => {
+  const importsJSON = await esmock(
+    '../local/importsJSONfile.js', {
+      '../local/example.json': {
+        'test-example': 'test-json-a'
+      }
+    })
+
+  if (/^(18|20)$/.test(process.versions.node.split('.')[0]))
+    return assert.ok(true)
+
+  assert.strictEqual(
+    Object.keys(importsJSON.JSONobj).sort().join(), 'example,test-example')
+  assert.strictEqual(importsJSON.JSONobj['test-example'], 'test-json-a')
+  assert.strictEqual(importsJSON.JSONobj['example'], 'json')
+})
+
+test('should mock imported json (strict)', async () => {
+  const importsJSON = await esmock.strict(
+    '../local/importsJSONfile.js', {
+      '../local/example.json': {
+        'test-example': 'test-json-b'
+      }
+    })
+
+  if (/^(18|20)$/.test(process.versions.node.split('.')[0]))
+    return assert.ok(true)
+
+  assert.strictEqual(
+    Object.keys(importsJSON.JSONobj).sort().join(), 'test-example')
+  assert.strictEqual(importsJSON.JSONobj['test-example'], 'test-json-b')
+})