diff --git a/test/form/dedupes-external-imports/_config.js b/test/form/dedupes-external-imports/_config.js
new file mode 100644
index 0000000..ed2bff2
--- /dev/null
+++ b/test/form/dedupes-external-imports/_config.js
@@ -0,0 +1,6 @@
+module.exports = {
+	description: 'dedupes external imports',
+	options: {
+		external: [ 'external' ]
+	}
+};
diff --git a/test/form/dedupes-external-imports/_expected/amd.js b/test/form/dedupes-external-imports/_expected/amd.js
new file mode 100644
index 0000000..be13b6a
--- /dev/null
+++ b/test/form/dedupes-external-imports/_expected/amd.js
@@ -0,0 +1,28 @@
+define(['external'], function (external) { 'use strict';
+
+	class Foo extends external.Component {
+		constructor () {
+			super();
+			this.isFoo = true;
+		}
+	}
+
+	class Bar extends external.Component {
+		constructor () {
+			super();
+			this.isBar = true;
+		}
+	}
+
+	class Baz extends external.Component {
+		constructor () {
+			super();
+			this.isBaz = true;
+		}
+	}
+
+	const foo = new Foo();
+	const bar = new Bar();
+	const baz = new Baz();
+
+});
diff --git a/test/form/dedupes-external-imports/_expected/cjs.js b/test/form/dedupes-external-imports/_expected/cjs.js
new file mode 100644
index 0000000..01dda8c
--- /dev/null
+++ b/test/form/dedupes-external-imports/_expected/cjs.js
@@ -0,0 +1,28 @@
+'use strict';
+
+var external = require('external');
+
+class Foo extends external.Component {
+	constructor () {
+		super();
+		this.isFoo = true;
+	}
+}
+
+class Bar extends external.Component {
+	constructor () {
+		super();
+		this.isBar = true;
+	}
+}
+
+class Baz extends external.Component {
+	constructor () {
+		super();
+		this.isBaz = true;
+	}
+}
+
+const foo = new Foo();
+const bar = new Bar();
+const baz = new Baz();
diff --git a/test/form/dedupes-external-imports/_expected/es6.js b/test/form/dedupes-external-imports/_expected/es6.js
new file mode 100644
index 0000000..884df6d
--- /dev/null
+++ b/test/form/dedupes-external-imports/_expected/es6.js
@@ -0,0 +1,26 @@
+import { Component } from 'external';
+
+class Foo extends Component {
+	constructor () {
+		super();
+		this.isFoo = true;
+	}
+}
+
+class Bar extends Component {
+	constructor () {
+		super();
+		this.isBar = true;
+	}
+}
+
+class Baz extends Component {
+	constructor () {
+		super();
+		this.isBaz = true;
+	}
+}
+
+const foo = new Foo();
+const bar = new Bar();
+const baz = new Baz();
diff --git a/test/form/dedupes-external-imports/_expected/iife.js b/test/form/dedupes-external-imports/_expected/iife.js
new file mode 100644
index 0000000..2656d84
--- /dev/null
+++ b/test/form/dedupes-external-imports/_expected/iife.js
@@ -0,0 +1,28 @@
+(function (external) { 'use strict';
+
+	class Foo extends external.Component {
+		constructor () {
+			super();
+			this.isFoo = true;
+		}
+	}
+
+	class Bar extends external.Component {
+		constructor () {
+			super();
+			this.isBar = true;
+		}
+	}
+
+	class Baz extends external.Component {
+		constructor () {
+			super();
+			this.isBaz = true;
+		}
+	}
+
+	const foo = new Foo();
+	const bar = new Bar();
+	const baz = new Baz();
+
+})(external);
diff --git a/test/form/dedupes-external-imports/_expected/umd.js b/test/form/dedupes-external-imports/_expected/umd.js
new file mode 100644
index 0000000..49ca55a
--- /dev/null
+++ b/test/form/dedupes-external-imports/_expected/umd.js
@@ -0,0 +1,32 @@
+(function (global, factory) {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory(require('external')) :
+	typeof define === 'function' && define.amd ? define(['external'], factory) :
+	factory(global.external);
+}(this, function (external) { 'use strict';
+
+	class Foo extends external.Component {
+		constructor () {
+			super();
+			this.isFoo = true;
+		}
+	}
+
+	class Bar extends external.Component {
+		constructor () {
+			super();
+			this.isBar = true;
+		}
+	}
+
+	class Baz extends external.Component {
+		constructor () {
+			super();
+			this.isBaz = true;
+		}
+	}
+
+	const foo = new Foo();
+	const bar = new Bar();
+	const baz = new Baz();
+
+}));
diff --git a/test/form/dedupes-external-imports/bar.js b/test/form/dedupes-external-imports/bar.js
new file mode 100644
index 0000000..ba19d22
--- /dev/null
+++ b/test/form/dedupes-external-imports/bar.js
@@ -0,0 +1,8 @@
+import { Component } from 'external';
+
+export default class Bar extends Component {
+	constructor () {
+		super();
+		this.isBar = true;
+	}
+}
diff --git a/test/form/dedupes-external-imports/baz.js b/test/form/dedupes-external-imports/baz.js
new file mode 100644
index 0000000..e52d4b0
--- /dev/null
+++ b/test/form/dedupes-external-imports/baz.js
@@ -0,0 +1,8 @@
+import { Component as Comp } from 'external';
+
+export default class Baz extends Comp {
+	constructor () {
+		super();
+		this.isBaz = true;
+	}
+}
diff --git a/test/form/dedupes-external-imports/foo.js b/test/form/dedupes-external-imports/foo.js
new file mode 100644
index 0000000..0646080
--- /dev/null
+++ b/test/form/dedupes-external-imports/foo.js
@@ -0,0 +1,8 @@
+import { Component } from 'external';
+
+export default class Foo extends Component {
+	constructor () {
+		super();
+		this.isFoo = true;
+	}
+}
diff --git a/test/form/dedupes-external-imports/main.js b/test/form/dedupes-external-imports/main.js
new file mode 100644
index 0000000..2fe3164
--- /dev/null
+++ b/test/form/dedupes-external-imports/main.js
@@ -0,0 +1,7 @@
+import Foo from './foo';
+import Bar from './bar';
+import Baz from './baz';
+
+const foo = new Foo();
+const bar = new Bar();
+const baz = new Baz();