Fix env transforms in node_modules

src/transforms/babel/env.js

@@ -18,13 +18,16 @@ async function getEnvConfig(asset, isSourceModule) {
   // Otherwise, load the source engines and generate a babel-present-env config.
   if (!isSourceModule) {
     let sourceEngines = await getTargetEngines(asset, false);
-    let sourceEnv = (await getEnvPlugins(sourceEngines, false)) || targetEnv;
+    let sourceEnv = await getEnvPlugins(sourceEngines, false);
 
-    // Do a diff of the returned plugins. We only need to process the remaining plugins to get to the app target.
-    let sourcePlugins = new Set(sourceEnv.map(p => p[0]));
-    targetEnv = targetEnv.filter(plugin => {
-      return !sourcePlugins.has(plugin[0]);
-    });
+    // Do a diff of the returned plugins if there is a known environment for the source.
+    // We only need to process the remaining plugins to get to the app target.
+    if (sourceEnv) {
+      let sourcePlugins = new Set(sourceEnv.map(p => p[0]));
+      targetEnv = targetEnv.filter(plugin => {
+        return !sourcePlugins.has(plugin[0]);
+      });
+    }
   }
 
   return {

src/utils/getTargetEngines.js

@@ -51,11 +51,6 @@ async function getTargetEngines(asset, isTargetApp) {
         }
       }
     }
-
-    // Fall back to package.engines.node for node_modules without any browser target info.
-    if (!isTargetApp && !targets.browsers && typeof nodeVersion === 'string') {
-      targets.node = nodeVersion;
-    }
   }
 
   // If we didn't find any targets, set some default engines for the target app.

test/javascript.js

@@ -1149,7 +1149,7 @@ describe('javascript', function() {
     );
   });
 
-  it('should not compile node_modules by default', async function() {
+  it('should make node_modules browser compatible', async function() {
     await bundle(
       path.join(__dirname, '/integration/babel-node-modules/index.js')
     );
@@ -1158,7 +1158,7 @@ describe('javascript', function() {
       path.join(__dirname, '/dist/index.js'),
       'utf8'
     );
-    assert(/class \S+ \{\}/.test(file));
+    assert(!/class \S+ \{\}/.test(file));
     assert(file.includes('function Bar'));
   });
 
@@ -1219,7 +1219,7 @@ describe('javascript', function() {
     assert(file.includes('function Bar'));
   });
 
-  it('should not compile node_modules with a source field in package.json when not symlinked', async function() {
+  it('Should compile node_modules without a defined target to match the projects browserslist', async function() {
     await bundle(
       path.join(
         __dirname,
@@ -1231,8 +1231,10 @@ describe('javascript', function() {
       path.join(__dirname, '/dist/index.js'),
       'utf8'
     );
-    assert(!file.includes('function Foo'));
-    assert(file.includes('function Bar'));
+
+    assert(!/class \S+ \{\}/.test(file), 'should not contain a class');
+    assert(file.includes('function Foo'), 'should have a function Foo');
+    assert(file.includes('function Bar'), 'should have a function Bar');
   });
 
   it('should support compiling JSX', async function() {