feat(commonjs): add esmExternals option

packages/commonjs/src/index.js

@@ -36,12 +36,23 @@ import {
 export default function commonjs(options = {}) {
   const extensions = options.extensions || ['.js'];
   const filter = createFilter(options.include, options.exclude);
-  // TODO Lukas document values: true, 'preferred', 'auto', false
-  const { ignoreGlobal, requireReturnsDefault: requireReturnsDefaultOption } = options;
+  // TODO Lukas document esmExternals
+  const {
+    ignoreGlobal,
+    requireReturnsDefault: requireReturnsDefaultOption,
+    esmExternals
+  } = options;
   const getRequireReturnsDefault =
     typeof requireReturnsDefaultOption === 'function'
       ? requireReturnsDefaultOption
       : () => requireReturnsDefaultOption;
+  let esmExternalIds;
+  const isEsmExternal =
+    typeof esmExternals === 'function'
+      ? esmExternals
+      : Array.isArray(esmExternals)
+      ? ((esmExternalIds = new Set(esmExternals)), (id) => esmExternalIds.has(id))
+      : () => esmExternals;
 
   const { dynamicRequireModuleSet, dynamicRequireModuleDirPaths } = getDynamicRequirePaths(
     options.dynamicRequireTargets
@@ -137,7 +148,10 @@ export default function commonjs(options = {}) {
 
       if (id.endsWith(EXTERNAL_SUFFIX)) {
         const actualId = getIdFromExternalProxyId(id);
-        return getUnknownRequireProxy(actualId, getRequireReturnsDefault(actualId));
+        return getUnknownRequireProxy(
+          actualId,
+          isEsmExternal(actualId) ? getRequireReturnsDefault(actualId) : true
+        );
       }
 
       if (id === DYNAMIC_PACKAGES_ID) {

packages/commonjs/test/fixtures/function/esm-externals-false/_config.js

@@ -0,0 +1,15 @@
+module.exports = {
+  description: 'always uses the default export when esmExternals is not used',
+  options: {
+    external: [
+      'external-cjs-exports',
+      'external-cjs-module-exports',
+      'external-esm-named',
+      'external-esm-mixed',
+      'external-esm-default'
+    ]
+  },
+  pluginOptions: {
+    esmExternals: false
+  }
+};

packages/commonjs/test/fixtures/function/esm-externals-false/main.js

@@ -0,0 +1,11 @@
+const externalExports = require('external-cjs-exports');
+const externalModuleExports = require('external-cjs-module-exports');
+const externalNamed = require('external-esm-named');
+const externalMixed = require('external-esm-mixed');
+const externalDefault = require('external-esm-default');
+
+t.deepEqual(externalExports, { foo: 'foo' }, 'external exports');
+t.deepEqual(externalModuleExports, 'bar', 'external module exports');
+t.deepEqual(externalNamed, { foo: 'foo' }, 'external named');
+t.deepEqual(externalMixed, 'bar', 'external mixed');
+t.deepEqual(externalDefault, 'bar', 'external default');

packages/commonjs/test/fixtures/function/esm-externals-function/_config.js

@@ -0,0 +1,36 @@
+const assert = require('assert');
+
+const called = {};
+
+module.exports = {
+  description: 'always uses the default export when esmExternals is not used',
+  options: {
+    external: [
+      'external-cjs-exports',
+      'external-cjs-module-exports',
+      'external-esm-named',
+      'external-esm-mixed',
+      'external-esm-default'
+    ],
+    plugins: [
+      {
+        name: 'test-plugin',
+        buildEnd() {
+          assert.deepStrictEqual(called, {
+            'external-cjs-exports': 1,
+            'external-cjs-module-exports': 1,
+            'external-esm-named': 1,
+            'external-esm-mixed': 1,
+            'external-esm-default': 1
+          });
+        }
+      }
+    ]
+  },
+  pluginOptions: {
+    esmExternals: (id) => {
+      called[id] = (called[id] || 0) + 1;
+      return id === 'external-esm-default';
+    }
+  }
+};

packages/commonjs/test/fixtures/function/esm-externals-function/main.js

@@ -0,0 +1,11 @@
+const externalExports = require('external-cjs-exports');
+const externalModuleExports = require('external-cjs-module-exports');
+const externalNamed = require('external-esm-named');
+const externalMixed = require('external-esm-mixed');
+const externalDefault = require('external-esm-default');
+
+t.deepEqual(externalExports, { foo: 'foo' }, 'external exports');
+t.deepEqual(externalModuleExports, 'bar', 'external module exports');
+t.deepEqual(externalNamed, { foo: 'foo' }, 'external named');
+t.deepEqual(externalMixed, 'bar', 'external mixed');
+t.deepEqual(externalDefault, { default: 'bar' }, 'external default');

packages/commonjs/test/fixtures/function/esm-externals-list/_config.js

@@ -0,0 +1,15 @@
+module.exports = {
+  description: 'always uses the default export when esmExternals is not used',
+  options: {
+    external: [
+      'external-cjs-exports',
+      'external-cjs-module-exports',
+      'external-esm-named',
+      'external-esm-mixed',
+      'external-esm-default'
+    ]
+  },
+  pluginOptions: {
+    esmExternals: ['external-esm-default']
+  }
+};

packages/commonjs/test/fixtures/function/esm-externals-list/main.js

@@ -0,0 +1,11 @@
+const externalExports = require('external-cjs-exports');
+const externalModuleExports = require('external-cjs-module-exports');
+const externalNamed = require('external-esm-named');
+const externalMixed = require('external-esm-mixed');
+const externalDefault = require('external-esm-default');
+
+t.deepEqual(externalExports, { foo: 'foo' }, 'external exports');
+t.deepEqual(externalModuleExports, 'bar', 'external module exports');
+t.deepEqual(externalNamed, { foo: 'foo' }, 'external named');
+t.deepEqual(externalMixed, 'bar', 'external mixed');
+t.deepEqual(externalDefault, { default: 'bar' }, 'external default');

packages/commonjs/test/fixtures/function/esm-externals-true/_config.js

@@ -0,0 +1,15 @@
+module.exports = {
+  description: 'always uses the default export when esmExternals is not used',
+  options: {
+    external: [
+      'external-cjs-exports',
+      'external-cjs-module-exports',
+      'external-esm-named',
+      'external-esm-mixed',
+      'external-esm-default'
+    ]
+  },
+  pluginOptions: {
+    esmExternals: true
+  }
+};

packages/commonjs/test/fixtures/function/esm-externals-true/main.js

@@ -0,0 +1,11 @@
+const externalExports = require('external-cjs-exports');
+const externalModuleExports = require('external-cjs-module-exports');
+const externalNamed = require('external-esm-named');
+const externalMixed = require('external-esm-mixed');
+const externalDefault = require('external-esm-default');
+
+t.deepEqual(externalExports, { foo: 'foo' }, 'external exports');
+t.deepEqual(externalModuleExports, 'bar', 'external module exports');
+t.deepEqual(externalNamed, { foo: 'foo' }, 'external named');
+t.deepEqual(externalMixed, { default: 'bar', foo: 'foo' }, 'external mixed');
+t.deepEqual(externalDefault, { default: 'bar' }, 'external default');

packages/commonjs/test/fixtures/function/esm-externals-undefined/_config.js

@@ -0,0 +1,12 @@
+module.exports = {
+  description: 'always uses the default export when esmExternals is not used',
+  options: {
+    external: [
+      'external-cjs-exports',
+      'external-cjs-module-exports',
+      'external-esm-named',
+      'external-esm-mixed',
+      'external-esm-default'
+    ]
+  }
+};

packages/commonjs/test/fixtures/function/esm-externals-undefined/main.js

@@ -0,0 +1,11 @@
+const externalExports = require('external-cjs-exports');
+const externalModuleExports = require('external-cjs-module-exports');
+const externalNamed = require('external-esm-named');
+const externalMixed = require('external-esm-mixed');
+const externalDefault = require('external-esm-default');
+
+t.deepEqual(externalExports, { foo: 'foo' }, 'external exports');
+t.deepEqual(externalModuleExports, 'bar', 'external module exports');
+t.deepEqual(externalNamed, { foo: 'foo' }, 'external named');
+t.deepEqual(externalMixed, 'bar', 'external mixed');
+t.deepEqual(externalDefault, 'bar', 'external default');

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-auto/_config.js

@@ -5,6 +5,7 @@ module.exports = {
     external: ['external-esm-named', 'external-esm-mixed', 'external-esm-default']
   },
   pluginOptions: {
-    requireReturnsDefault: 'auto'
+    requireReturnsDefault: 'auto',
+    esmExternals: true
   }
 };

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-false/_config.js

@@ -5,6 +5,7 @@ module.exports = {
     external: ['external-esm-named', 'external-esm-mixed', 'external-esm-default']
   },
   pluginOptions: {
-    requireReturnsDefault: false
+    requireReturnsDefault: false,
+    esmExternals: true
   }
 };

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-function-called-once/_config.js

@@ -1,10 +1,6 @@
 const assert = require('assert');
 
-const called = {
-  'main.js': 0,
-  'both.js': 0,
-  'other.js': 0
-};
+const called = {};
 
 module.exports = {
   description: 'only calls a requireReturnsDefault function once per id',
@@ -37,7 +33,7 @@ module.exports = {
     requireReturnsDefault: (id) => {
       const [prefix, name] = id.split('_');
       if (prefix === 'dep') {
-        called[name] += 1;
+        called[name] = (called[name] || 0) + 1;
         return 'preferred';
       }
       return false;

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-function-external/_config.js

@@ -8,6 +8,7 @@ module.exports = {
       if (id === 'external-esm-mixed') return true;
       if (id === 'external-esm-default') return false;
       return 'auto';
-    }
+    },
+    esmExternals: true
   }
 };

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-preferred/_config.js

@@ -5,6 +5,7 @@ module.exports = {
     external: ['external-esm-named', 'external-esm-mixed', 'external-esm-default']
   },
   pluginOptions: {
-    requireReturnsDefault: 'preferred'
+    requireReturnsDefault: 'preferred',
+    esmExternals: true
   }
 };

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-true/_config.js

@@ -5,6 +5,7 @@ module.exports = {
     external: ['external-esm-named', 'external-esm-mixed', 'external-esm-default']
   },
   pluginOptions: {
-    requireReturnsDefault: true
+    requireReturnsDefault: true,
+    esmExternals: true
   }
 };

packages/commonjs/test/fixtures/function/import-esm-require-returns-default-undefined/_config.js

@@ -3,5 +3,8 @@ module.exports = {
     'returns the namespace when requiring an ES module and requireReturnsDefault is missing',
   options: {
     external: ['external-esm-named', 'external-esm-mixed', 'external-esm-default']
+  },
+  pluginOptions: {
+    esmExternals: true
   }
 };