Merge pull request #23 from iambumblehead/add-low-tech-support-for-in…

…line-await-import-mock

add test and support for await import

README.md

@@ -97,9 +97,49 @@ test('should mock modules and local files at same time', async t => {
 });
 ```
 
+## Examle, mocking await import( 'modulename' )
+
+When `esmock` loads and returns a module it deletes mocking definitions from a cache by default. Disable this behaviour when using 'await import', so that mocked definitions can be loaded during test runtime. A function can be called later to clear the cache.
+
+``` javascript
+export default async function usesAwaitImport (config) {
+  const eslint = (await import('eslint'));
+
+  return new eslint.ESLint({ baseConfig : config });
+};
+```
+
+In the test file, define an 'options' object before local and global mock definitions, `{ isPurge: false }`,
+``` javascript
+test('mocks inline `async import("name")`', async t => {
+  const writeJSConfigFile = await esmock('./local/usesAwaitImport.mjs', {
+    isPurge : false
+  }, {
+    eslint : {
+      ESLint : function (o) {
+        this.stringify = () => JSON.stringify(o);
+
+        return this;
+      }
+    }
+  });
+
+  t.is((await writeJSConfigFile('config')).stringify(), JSON.stringify({
+    baseConfig : 'config'
+  }));
+
+  // clear the cache
+  esmock.purge(writeJSConfigFile);
+});
+```
+
+If there are not many tests or if each test completes in a separate process, skipping `esmock.purge()` is OK
+
 
 ### changelog
 
+ * 1.2.0 _Nov.26.2021_
+   * add support for await import
  * 1.1.0 _Nov.25.2021_
    * add windows-latest to testing pipeline and begin windows support
    * removed files and functions no longer needed

package.json

@@ -1,6 +1,6 @@
 {
   "name": "esmock",
-  "version": "1.1.0",
+  "version": "1.2.0",
   "license": "MIT",
   "readmeFilename": "README.md",
   "description": "mock esm modules for unit-tests",

spec/esmock.spec.js

@@ -254,3 +254,36 @@ test('returns spread-imported [object Module] default export', async t => {
 
   t.is(main.exportedFunction(), 'foobar');
 });
+
+test('mocks inline `async import("name")`', async t => {
+  const writeJSConfigFile = await esmock('./local/usesInlineImport.mjs', {
+    isPurge : false
+  }, {
+    eslint : {
+      ESLint : function (...o) {
+        this.stringify = () => JSON.stringify(...o);
+
+        return this;
+      }
+    }
+  });
+
+  t.is(
+    (await writeJSConfigFile('config', 'filePath')).stringify(),
+    JSON.stringify({
+      baseConfig : 'config',
+      fix : true,
+      useEslintrc : false,
+      filePath : 'filePath'
+    }));
+
+  const [ , key ] = writeJSConfigFile.esmockKey.match(/esmockKey=(\d*)/);
+  const keyRe = new RegExp(`esmockKey=${key}[^d]`);
+
+  const moduleKeys = Object.keys(esmock.esmockCache.mockDefs)
+    .filter(moduleKey => keyRe.test(moduleKey));
+
+  t.true(moduleKeys.every(mkey => esmock.esmockCache.mockDefs[mkey]));
+  esmock.purge(writeJSConfigFile);
+  t.true(moduleKeys.every(mkey => esmock.esmockCache.mockDefs[mkey] === null));
+});

spec/local/usesInlineImport.mjs

@@ -0,0 +1,13 @@
+
+async function writeJSConfigFile (config, filePath) {
+  const eslint = (await import('eslint'));
+
+  return new eslint.ESLint({
+    baseConfig : config,
+    fix : true,
+    useEslintrc : false,
+    filePath
+  });
+};
+
+export default writeJSConfigFile;

src/esmock.js

@@ -8,20 +8,35 @@ import {
   esmockCache
 } from './esmockCache.js';
 
+const argHasKey = (arg, key) => (
+  arg && !/number|boolean/.test(typeof arg) && key in arg);
+
 const esmock = async (modulePath, mockDefs, globalDefs, opt) => {
   // this functions caller is stack item '2'
   const calleePath = new Error().stack.split('\n')[2]
     .replace(/^.*file:\/\//, '') // rm everything before filepathfe
     .replace(/:[\d]*:[\d]*.*$/, '') // rm line and row number
     .replace(/^.*:/, ''); // rm windows-style drive locations
+
+  // remap params in case options are provided as first arg
+  [ opt, mockDefs, globalDefs ] = argHasKey(mockDefs, 'isPurge')
+    ? [ mockDefs || {}, globalDefs || {}, opt || {} ]
+    : [ opt || {}, mockDefs || {}, globalDefs || {} ];
+
   const modulePathKey = await esmockModuleMock(
     calleePath, modulePath, mockDefs || {}, globalDefs || {}, opt || {});
 
   const importedModule = await import(modulePathKey);
 
-  esmockModuleImportedPurge(modulePathKey);
+  if (opt.isPurge !== false)
+    esmockModuleImportedPurge(modulePathKey);
 
-  return esmockModuleImportedSanitize(importedModule);
+  return esmockModuleImportedSanitize(importedModule, modulePathKey);
+};
+
+esmock.purge = mockModule => {
+  if (argHasKey(mockModule, 'esmockKey'))
+    esmockModuleImportedPurge(mockModule.esmockKey);
 };
 
 esmock.esmockCache = esmockCache;

src/esmockCache.js

@@ -1,5 +1,3 @@
-import path from 'path';
-
 const esmockCache = {
   resolvedPaths : {},
   isESM : {},
@@ -15,9 +13,6 @@ const esmockCacheSet = (key, mockDef) => (
 const esmockCacheGet = key => (
   esmockCache.mockDefs[key]);
 
-const esmockCacheResolvePathKey = (calleePath, localPath) => (
-  path.join(path.dirname(calleePath), localPath));
-
 const esmockCacheResolvedPathIsESMGet = mockPathFull => (
   esmockCache.isESM[mockPathFull]);
 
@@ -30,7 +25,6 @@ export {
   esmockCache,
   esmockCacheSet,
   esmockCacheGet,
-  esmockCacheResolvePathKey,
   esmockCacheResolvedPathIsESMGet,
   esmockCacheResolvedPathIsESMSet
 };

src/esmockModule.js

@@ -73,22 +73,22 @@ const esmockModuleIsESM = (mockPathFull, isesm) => {
 
 // return the default value directly, so that the esmock caller
 // does not need to lookup default as in "esmockedValue.default"
-const esmockModuleImportedSanitize = importedModule => {
+const esmockModuleImportedSanitize = (importedModule, esmockKey) => {
   const importedDefault = 'default' in importedModule
         && importedModule.default;
 
   if (!/boolean|string|number/.test(typeof importedDefault)) {
     // an example of [object Module]: import * as mod from 'fs'; export mod;
     return Object.prototype.toString.call(importedDefault) === '[object Module]'
-      ? Object.assign({}, importedDefault, importedModule)
-      : Object.assign(importedDefault, importedModule);
+      ? Object.assign({}, importedDefault, importedModule, { esmockKey })
+      : Object.assign(importedDefault, importedModule, { esmockKey });
   }
 
   return importedModule;
 };
 
 const esmockModuleImportedPurge = modulePathKey => {
-  const purgeKey = key => esmockCacheSet(key, null);
+  const purgeKey = key => key !== 'null' && esmockCacheSet(key, null);
   const [ url, keys ] = modulePathKey.split('#esmockModuleKeys=');
 
   String(keys).split('#').forEach(purgeKey);