test for method call side effects

src/ast/analyse.js

@@ -165,7 +165,7 @@ export default function analyse ( ast, magicString, module ) {
 				node.arguments.forEach( addNode );
 			}
 
-			// TODO UpdateExpression
+			// TODO UpdateExpressions, method calls?
 		}
 
 		walk( statement, {

test/samples/method-call-side-effects/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'assumes methods may mutate objects passed in, and self'
+};

test/samples/method-call-side-effects/main.js

@@ -0,0 +1,5 @@
+import object from './object';
+import thing from './thing';
+
+assert.ok( object.mutated );
+assert.ok( thing.methodWasCalled );

test/samples/method-call-side-effects/object.js

@@ -0,0 +1,6 @@
+import thing from './thing';
+
+var object = {};
+thing.mutate( object );
+
+export default object;

test/samples/method-call-side-effects/thing.js

@@ -0,0 +1,8 @@
+export default {
+	mutate: function ( object ) {
+		object.mutated = true;
+		this.methodWasCalled = true;
+	},
+
+	methodWasCalled: false
+};

test/test.js

@@ -36,6 +36,10 @@ describe( 'rollup', function () {
 						console.log( result.code );
 						throw err;
 					}
+
+					if ( config.show ) {
+						console.log( result.code + '\n\n\n' );
+					}
 				});
 		});
 	});