ensure reassigned exports are declared in an ES bundle (#755)

src/Module.js

@@ -462,7 +462,7 @@ export default class Module {
 				if ( statement.node.isSynthetic ) return;
 
 				// skip `export { foo, bar, baz }`
-				if ( statement.node.specifiers.length ) {
+				if ( statement.node.declaration === null ) {
 					magicString.remove( statement.start, statement.next );
 					return;
 				}
@@ -555,11 +555,21 @@ export default class Module {
 					const name = extractNames( statement.node.declaration.declarations[ 0 ].id )[ 0 ];
 					const declaration = this.declarations[ name ];
 
+					// TODO is this even possible?
 					if ( !declaration ) throw new Error( `Missing declaration for ${name}!` );
 
-					const end = declaration.exportName && declaration.isReassigned ?
-						statement.node.declaration.declarations[0].start :
-						statement.node.declaration.start;
+					let end;
+
+					if ( es ) {
+						end = statement.node.declaration.start;
+					} else {
+						if ( declaration.exportName && declaration.isReassigned ) {
+							const declarator = statement.node.declaration.declarations[0];
+							end = declarator.init ? declarator.start : statement.next;
+						} else {
+							end = statement.node.declaration.start
+						}
+					}
 
 					magicString.remove( statement.node.start, end );
 				}

test/form/assignment-to-exports-class-declaration/_expected/es.js

@@ -1,4 +1,4 @@
-Foo = class Foo {}
+let Foo = class Foo {}
 Foo = lol( Foo );
 
-export { Foo };
+export { Foo };

test/form/assignment-to-exports/_config.js

@@ -0,0 +1,6 @@
+module.exports = {
+	description: 'declares updated variable in ES output (#755)',
+	options: {
+		moduleName: 'bundle'
+	}
+};

test/form/assignment-to-exports/_expected/amd.js

@@ -0,0 +1,7 @@
+define(['exports'], function (exports) { 'use strict';
+
+	exports.foo = 1;
+
+	Object.defineProperty(exports, '__esModule', { value: true });
+
+});

test/form/assignment-to-exports/_expected/cjs.js

@@ -0,0 +1,5 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', { value: true });
+
+exports.foo = 1;

test/form/assignment-to-exports/_expected/es.js

@@ -0,0 +1,4 @@
+var foo;
+foo = 1;
+
+export { foo };

test/form/assignment-to-exports/_expected/iife.js

@@ -0,0 +1,6 @@
+(function (exports) {
+	'use strict';
+
+	exports.foo = 1;
+
+}((this.bundle = this.bundle || {})));

test/form/assignment-to-exports/_expected/umd.js

@@ -0,0 +1,11 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
+	typeof define === 'function' && define.amd ? define(['exports'], factory) :
+	(factory((global.bundle = global.bundle || {})));
+}(this, function (exports) { 'use strict';
+
+	exports.foo = 1;
+
+	Object.defineProperty(exports, '__esModule', { value: true });
+
+}));

test/form/assignment-to-exports/main.js

@@ -0,0 +1,2 @@
+export var foo;
+foo = 1;