fix(commonjs): do not transform "typeof exports" for mixed modules

resolves #1014

packages/commonjs/src/transform-commonjs.js

@@ -369,9 +369,10 @@ export default async function transformCommonjs(
             if (scope.contains(flattened.name)) return;
 
             if (
-              flattened.keypath === 'module.exports' ||
-              flattened.keypath === 'module' ||
-              flattened.keypath === 'exports'
+              !isEsModule &&
+              (flattened.keypath === 'module.exports' ||
+                flattened.keypath === 'module' ||
+                flattened.keypath === 'exports')
             ) {
               magicString.overwrite(node.start, node.end, `'object'`, {
                 storeName: false

packages/commonjs/test/fixtures/samples/mixed-module-typeof-exports/_config.js

@@ -0,0 +1,4 @@
+module.exports = {
+  description: 'replaces "typeof exports" with "undefined" in mixed modules',
+  pluginOptions: { transformMixedEsModules: true }
+};

packages/commonjs/test/fixtures/samples/mixed-module-typeof-exports/foo.js

@@ -0,0 +1 @@
+module.exports = 21;

packages/commonjs/test/fixtures/samples/mixed-module-typeof-exports/main.js

@@ -0,0 +1,7 @@
+const foo = require('./foo');
+
+if (typeof exports !== 'undefined') {
+  throw new Error('There should be no global exports in an ES module');
+}
+
+export { foo as default };

packages/commonjs/test/snapshots/function.js.md

@@ -3050,8 +3050,10 @@ Generated by [AVA](https://avajs.dev).
         root = window;␊
       } else if (typeof global !== 'undefined') {␊
         root = global;␊
-      } else {␊
+      } else if (typeof module !== 'undefined') {␊
         root = module;␊
+      } else {␊
+        root = Function('return this')(); // eslint-disable-line no-new-func␊
       }␊
       ␊
       root.pollution = 'foo';␊
@@ -4725,6 +4727,19 @@ Generated by [AVA](https://avajs.dev).
       `,
     }
 
+## load-cycle-parallel
+
+> Snapshot 1
+
+    {
+      'main.js': `'use strict';␊
+      ␊
+      var main = {};␊
+      ␊
+      module.exports = main;␊
+      `,
+    }
+
 ## module-meta-properties
 
 > Snapshot 1
@@ -7251,16 +7266,3 @@ Generated by [AVA](https://avajs.dev).
       module.exports = main;␊
       `,
     }
-
-## load-cycle-parallel
-
-> Snapshot 1
-
-    {
-      'main.js': `'use strict';␊
-      ␊
-      var main = {};␊
-      ␊
-      module.exports = main;␊
-      `,
-    }

packages/commonjs/test/snapshots/test.js.md

@@ -100,3 +100,18 @@ Generated by [AVA](https://avajs.dev).
     ␊
     module.exports = main;␊
     `
+
+## does not transform typeof exports for mixed modules
+
+> Snapshot 1
+
+    `var foo$1 = 21;␊
+    ␊
+    const foo = foo$1;␊
+    ␊
+    if (typeof exports !== 'undefined') {␊
+      throw new Error('There should be no global exports in an ES module');␊
+    }␊
+    ␊
+    export { foo as default };␊
+    `

packages/commonjs/test/test.js

@@ -331,8 +331,8 @@ test('typeof transforms: sinon', async (t) => {
   } = await bundle.generate({ format: 'es' });
 
   t.is(code.indexOf('typeof require'), -1, code);
-  // t.not( code.indexOf( 'typeof module' ), -1, code ); // #151 breaks this test
-  // t.not( code.indexOf( 'typeof define' ), -1, code ); // #144 breaks this test
+  t.is(code.indexOf('typeof module'), -1, code);
+  t.is(code.indexOf('typeof define'), -1, code);
 });
 
 test('deconflicts helper name', async (t) => {
@@ -717,3 +717,17 @@ test('throws when there is a dynamic require from outside dynamicRequireRoot', a
     dynamicRequireRoot
   });
 });
+
+test('does not transform typeof exports for mixed modules', async (t) => {
+  const bundle = await rollup({
+    input: 'fixtures/samples/mixed-module-typeof-exports/main.js',
+    plugins: [commonjs({ transformMixedEsModules: true })]
+  });
+
+  const {
+    output: [{ code }]
+  } = await bundle.generate({ format: 'es' });
+
+  t.is(code.includes('typeof exports'), true, '"typeof exports" not found in the code');
+  t.snapshot(code);
+});