more robust interop

src/finalisers/shared/getInteropBlock.js

@@ -1,6 +1,12 @@
 export default function getInteropBlock ( bundle ) {
 	return bundle.externalModules
-		.filter( module => module.needsDefault && module.needsNamed )
-		.map( module => `var ${module.name}__default = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};` )
+		.map( module => {
+			return module.needsDefault ?
+				( module.needsNamed ?
+					`var ${module.name}__default = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};` :
+					`${module.name} = 'default' in ${module.name} ? ${module.name}['default'] : ${module.name};` ) :
+				null;
+		})
+		.filter( Boolean )
 		.join( '\n' );
 }

test/form/external-imports-custom-names/_expected/amd.js

@@ -1,5 +1,7 @@
 define(['jquery'], function ($) { 'use strict';
 
+	$ = 'default' in $ ? $['default'] : $;
+
 	$( function () {
 		$( 'body' ).html( '<h1>hello world!</h1>' );
 	});

test/form/external-imports-custom-names/_expected/iife.js

@@ -1,5 +1,7 @@
 (function ($) { 'use strict';
 
+	$ = 'default' in $ ? $['default'] : $;
+
 	$( function () {
 		$( 'body' ).html( '<h1>hello world!</h1>' );
 	});

test/form/external-imports-custom-names/_expected/umd.js

@@ -4,6 +4,8 @@
 	factory(global.jQuery);
 }(this, function ($) { 'use strict';
 
+	$ = 'default' in $ ? $['default'] : $;
+
 	$( function () {
 		$( 'body' ).html( '<h1>hello world!</h1>' );
 	});

test/form/external-imports/_expected/amd.js

@@ -1,5 +1,6 @@
 define(['factory', 'baz', 'shipping-port', 'alphabet'], function (factory, baz, containers, alphabet) { 'use strict';
 
+	factory = 'default' in factory ? factory['default'] : factory;
 	var alphabet__default = 'default' in alphabet ? alphabet['default'] : alphabet;
 
 	factory( null );

test/form/external-imports/_expected/iife.js

@@ -1,5 +1,6 @@
 (function (factory,baz,containers,alphabet) { 'use strict';
 
+	factory = 'default' in factory ? factory['default'] : factory;
 	var alphabet__default = 'default' in alphabet ? alphabet['default'] : alphabet;
 
 	factory( null );

test/form/external-imports/_expected/umd.js

@@ -4,6 +4,7 @@
 	factory(global.factory,global.baz,global.containers,global.alphabet);
 }(this, function (factory,baz,containers,alphabet) { 'use strict';
 
+	factory = 'default' in factory ? factory['default'] : factory;
 	var alphabet__default = 'default' in alphabet ? alphabet['default'] : alphabet;
 
 	factory( null );