Merge pull request #204 from kellyselden/_shouldDoNothing

add a no-op optimization

index.js

@@ -49,8 +49,14 @@ module.exports = {
     let description = `000${++count}`.slice(-3);
     let postDebugTree = this._debugTree(inputTree, `${description}:input`);
 
-    let BabelTranspiler = require('broccoli-babel-transpiler');
-    let output = new BabelTranspiler(postDebugTree, this.buildBabelOptions(config));
+    let options = this.buildBabelOptions(config);
+    let output;
+    if (this._shouldDoNothing(options)) {
+      output = postDebugTree;
+    } else {
+      let BabelTranspiler = require('broccoli-babel-transpiler');
+      output = new BabelTranspiler(postDebugTree, options);
+    }
 
     return this._debugTree(output, `${description}:output`);
   },
@@ -378,4 +384,9 @@ module.exports = {
 
     return checker.exists();
   },
+
+  // detect if running babel would do nothing... and do nothing instead
+  _shouldDoNothing(options) {
+    return !options.sourceMaps && !options.plugins.length;
+  }
 };

node-tests/addon-test.js

@@ -343,6 +343,33 @@ describe('ember-cli-babel', function() {
       }));
 
     });
+
+    describe('_shouldDoNothing', function() {
+      it("will no-op if nothing to do", co.wrap(function* () {
+        input.write({
+          "foo.js": `invalid code`
+        });
+
+        subject = this.addon.transpileTree(input.path(), {
+          'ember-cli-babel': {
+            compileModules: false,
+            disablePresetEnv: true,
+            disableDebugTooling: true,
+            disableEmberModulesAPIPolyfill: true
+          }
+        });
+
+        output = createBuilder(subject);
+
+        yield output.build();
+
+        expect(
+          output.read()
+        ).to.deep.equal({
+          "foo.js": `invalid code`
+        });
+      }));
+    });
   });
 
   describe('_getAddonOptions', function() {