diff --git a/test/js/samples/custom-element-basic/expected-bundle.js b/test/js/samples/custom-element-basic/expected-bundle.js
index aff7954c60..f234f6dca8 100644
--- a/test/js/samples/custom-element-basic/expected-bundle.js
+++ b/test/js/samples/custom-element-basic/expected-bundle.js
@@ -162,23 +162,31 @@ var proto = {
 };
 
 function create_main_fragment ( state, component ) {
-	var div, text;
+	var h1, text, text_1, text_2;
 
 	return {
 		create: function () {
-			div = createElement( 'div' );
-			text = createText( "I am shadow DOM" );
+			h1 = createElement( 'h1' );
+			text = createText( "Hello " );
+			text_1 = createText( state.name );
+			text_2 = createText( "!" );
 		},
 
 		mount: function ( target, anchor ) {
-			insertNode( div, target, anchor );
-			appendNode( text, div );
+			insertNode( h1, target, anchor );
+			appendNode( text, h1 );
+			appendNode( text_1, h1 );
+			appendNode( text_2, h1 );
 		},
 
-		update: noop,
+		update: function ( changed, state ) {
+			if ( changed.name ) {
+				text_1.data = state.name;
+			}
+		},
 
 		unmount: function () {
-			detachNode( div );
+			detachNode( h1 );
 		},
 
 		destroy: noop
@@ -209,6 +217,22 @@ class SvelteComponent extends HTMLElement {
 			this._fragment.mount( this.attachShadow({ mode: 'open' }), null );
 		}
 	}
+
+	static get observedAttributes() {
+		return ["name"];
+	}
+
+	get name() {
+		return this.get('name');
+	}
+
+	set name(value) {
+		this.set({ name: value });
+	}
+
+	attributeChangedCallback ( attr, oldValue, newValue ) {
+		this.set({ [attr]: newValue });
+	}
 }
 
 customElements.define('custom-element', SvelteComponent);
diff --git a/test/js/samples/custom-element-basic/expected.js b/test/js/samples/custom-element-basic/expected.js
index 50023bb4ec..1e1b8deac0 100644
--- a/test/js/samples/custom-element-basic/expected.js
+++ b/test/js/samples/custom-element-basic/expected.js
@@ -1,23 +1,31 @@
 import { appendNode, assign, createElement, createText, detachNode, insertNode, noop, proto } from "svelte/shared.js";
 
 function create_main_fragment ( state, component ) {
-	var div, text;
+	var h1, text, text_1, text_2;
 
 	return {
 		create: function () {
-			div = createElement( 'div' );
-			text = createText( "I am shadow DOM" );
+			h1 = createElement( 'h1' );
+			text = createText( "Hello " );
+			text_1 = createText( state.name );
+			text_2 = createText( "!" );
 		},
 
 		mount: function ( target, anchor ) {
-			insertNode( div, target, anchor );
-			appendNode( text, div );
+			insertNode( h1, target, anchor );
+			appendNode( text, h1 );
+			appendNode( text_1, h1 );
+			appendNode( text_2, h1 );
 		},
 
-		update: noop,
+		update: function ( changed, state ) {
+			if ( changed.name ) {
+				text_1.data = state.name;
+			}
+		},
 
 		unmount: function () {
-			detachNode( div );
+			detachNode( h1 );
 		},
 
 		destroy: noop
@@ -48,6 +56,22 @@ class SvelteComponent extends HTMLElement {
 			this._fragment.mount( this.attachShadow({ mode: 'open' }), null );
 		}
 	}
+
+	static get observedAttributes() {
+		return ["name"];
+	}
+
+	get name() {
+		return this.get('name');
+	}
+
+	set name(value) {
+		this.set({ name: value });
+	}
+
+	attributeChangedCallback ( attr, oldValue, newValue ) {
+		this.set({ [attr]: newValue });
+	}
 }
 
 customElements.define('custom-element', SvelteComponent);
diff --git a/test/js/samples/custom-element-basic/input.html b/test/js/samples/custom-element-basic/input.html
index 3e00e7121f..6cc7a9e7af 100644
--- a/test/js/samples/custom-element-basic/input.html
+++ b/test/js/samples/custom-element-basic/input.html
@@ -1,4 +1,4 @@
-<div>I am shadow DOM</div>
+<h1>Hello {{name}}!</h1>
 
 <script>
 	export default {
diff --git a/test/js/samples/custom-element-slot/_config.js b/test/js/samples/custom-element-slot/_config.js
new file mode 100644
index 0000000000..735dd07e62
--- /dev/null
+++ b/test/js/samples/custom-element-slot/_config.js
@@ -0,0 +1,5 @@
+export default {
+	options: {
+		customElement: true
+	}
+};
\ No newline at end of file
diff --git a/test/js/samples/custom-element-slot/expected-bundle.js b/test/js/samples/custom-element-slot/expected-bundle.js
new file mode 100644
index 0000000000..1250dbb624
--- /dev/null
+++ b/test/js/samples/custom-element-slot/expected-bundle.js
@@ -0,0 +1,249 @@
+function noop() {}
+
+function assign(target) {
+	var k,
+		source,
+		i = 1,
+		len = arguments.length;
+	for (; i < len; i++) {
+		source = arguments[i];
+		for (k in source) target[k] = source[k];
+	}
+
+	return target;
+}
+
+function appendNode(node, target) {
+	target.appendChild(node);
+}
+
+function insertNode(node, target, anchor) {
+	target.insertBefore(node, anchor);
+}
+
+function detachNode(node) {
+	node.parentNode.removeChild(node);
+}
+
+function createElement(name) {
+	return document.createElement(name);
+}
+
+function createText(data) {
+	return document.createTextNode(data);
+}
+
+function setAttribute(node, attribute, value) {
+	node.setAttribute(attribute, value);
+}
+
+function destroy(detach) {
+	this.destroy = noop;
+	this.fire('destroy');
+	this.set = this.get = noop;
+
+	if (detach !== false) this._fragment.unmount();
+	this._fragment.destroy();
+	this._fragment = this._state = null;
+}
+
+function differs(a, b) {
+	return a !== b || ((a && typeof a === 'object') || typeof a === 'function');
+}
+
+function dispatchObservers(component, group, changed, newState, oldState) {
+	for (var key in group) {
+		if (!changed[key]) continue;
+
+		var newValue = newState[key];
+		var oldValue = oldState[key];
+
+		var callbacks = group[key];
+		if (!callbacks) continue;
+
+		for (var i = 0; i < callbacks.length; i += 1) {
+			var callback = callbacks[i];
+			if (callback.__calling) continue;
+
+			callback.__calling = true;
+			callback.call(component, newValue, oldValue);
+			callback.__calling = false;
+		}
+	}
+}
+
+function get(key) {
+	return key ? this._state[key] : this._state;
+}
+
+function fire(eventName, data) {
+	var handlers =
+		eventName in this._handlers && this._handlers[eventName].slice();
+	if (!handlers) return;
+
+	for (var i = 0; i < handlers.length; i += 1) {
+		handlers[i].call(this, data);
+	}
+}
+
+function observe(key, callback, options) {
+	var group = options && options.defer
+		? this._observers.post
+		: this._observers.pre;
+
+	(group[key] || (group[key] = [])).push(callback);
+
+	if (!options || options.init !== false) {
+		callback.__calling = true;
+		callback.call(this, this._state[key]);
+		callback.__calling = false;
+	}
+
+	return {
+		cancel: function() {
+			var index = group[key].indexOf(callback);
+			if (~index) group[key].splice(index, 1);
+		}
+	};
+}
+
+function on(eventName, handler) {
+	if (eventName === 'teardown') return this.on('destroy', handler);
+
+	var handlers = this._handlers[eventName] || (this._handlers[eventName] = []);
+	handlers.push(handler);
+
+	return {
+		cancel: function() {
+			var index = handlers.indexOf(handler);
+			if (~index) handlers.splice(index, 1);
+		}
+	};
+}
+
+function set(newState) {
+	this._set(assign({}, newState));
+	if (this._root._lock) return;
+	this._root._lock = true;
+	callAll(this._root._beforecreate);
+	callAll(this._root._oncreate);
+	callAll(this._root._aftercreate);
+	this._root._lock = false;
+}
+
+function _set(newState) {
+	var oldState = this._state,
+		changed = {},
+		dirty = false;
+
+	for (var key in newState) {
+		if (differs(newState[key], oldState[key])) changed[key] = dirty = true;
+	}
+	if (!dirty) return;
+
+	this._state = assign({}, oldState, newState);
+	this._recompute(changed, this._state, oldState, false);
+	if (this._bind) this._bind(changed, this._state);
+	dispatchObservers(this, this._observers.pre, changed, this._state, oldState);
+	this._fragment.update(changed, this._state);
+	dispatchObservers(this, this._observers.post, changed, this._state, oldState);
+}
+
+function callAll(fns) {
+	while (fns && fns.length) fns.pop()();
+}
+
+var proto = {
+	destroy: destroy,
+	get: get,
+	fire: fire,
+	observe: observe,
+	on: on,
+	set: set,
+	teardown: destroy,
+	_recompute: noop,
+	_set: _set
+};
+
+function create_main_fragment ( state, component ) {
+	var div, slot, p, text, text_2, slot_1, p_1, text_3;
+
+	return {
+		create: function () {
+			div = createElement( 'div' );
+			slot = createElement( 'slot' );
+			p = createElement( 'p' );
+			text = createText( "default fallback content" );
+			text_2 = createText( "\n\n\t" );
+			slot_1 = createElement( 'slot' );
+			p_1 = createElement( 'p' );
+			text_3 = createText( "foo fallback content" );
+			this.hydrate();
+		},
+
+		hydrate: function ( nodes ) {
+			setAttribute( slot_1, 'name', "foo" );
+		},
+
+		mount: function ( target, anchor ) {
+			insertNode( div, target, anchor );
+			appendNode( slot, div );
+			appendNode( p, slot );
+			appendNode( text, p );
+			appendNode( text_2, div );
+			appendNode( slot_1, div );
+			appendNode( p_1, slot_1 );
+			appendNode( text_3, p_1 );
+		},
+
+		update: noop,
+
+		unmount: function () {
+			detachNode( div );
+		},
+
+		destroy: noop
+	};
+}
+
+class SvelteComponent extends HTMLElement {
+	constructor(options = {}) {
+		super();
+		this.options = options;
+		this._state = options.data || {};
+
+		this._observers = {
+			pre: Object.create( null ),
+			post: Object.create( null )
+		};
+
+		this._handlers = Object.create( null );
+
+		this._root = options._root || this;
+		this._yield = options._yield;
+		this._bind = options._bind;
+
+		this._fragment = create_main_fragment( this._state, this );
+
+		if ( !options._root ) {
+			this._fragment.create();
+			this._fragment.mount( this.attachShadow({ mode: 'open' }), null );
+		}
+	}
+
+	static get observedAttributes() {
+		return [];
+	}
+
+
+
+	attributeChangedCallback ( attr, oldValue, newValue ) {
+		this.set({ [attr]: newValue });
+	}
+}
+
+customElements.define('custom-element', SvelteComponent);
+
+assign( SvelteComponent.prototype, proto );
+
+export default SvelteComponent;
diff --git a/test/js/samples/custom-element-slot/expected.js b/test/js/samples/custom-element-slot/expected.js
new file mode 100644
index 0000000000..831cfce1d0
--- /dev/null
+++ b/test/js/samples/custom-element-slot/expected.js
@@ -0,0 +1,84 @@
+import { appendNode, assign, createElement, createText, detachNode, insertNode, noop, proto, setAttribute } from "svelte/shared.js";
+
+function create_main_fragment ( state, component ) {
+	var div, slot, p, text, text_2, slot_1, p_1, text_3;
+
+	return {
+		create: function () {
+			div = createElement( 'div' );
+			slot = createElement( 'slot' );
+			p = createElement( 'p' );
+			text = createText( "default fallback content" );
+			text_2 = createText( "\n\n\t" );
+			slot_1 = createElement( 'slot' );
+			p_1 = createElement( 'p' );
+			text_3 = createText( "foo fallback content" );
+			this.hydrate();
+		},
+
+		hydrate: function ( nodes ) {
+			setAttribute( slot_1, 'name', "foo" );
+		},
+
+		mount: function ( target, anchor ) {
+			insertNode( div, target, anchor );
+			appendNode( slot, div );
+			appendNode( p, slot );
+			appendNode( text, p );
+			appendNode( text_2, div );
+			appendNode( slot_1, div );
+			appendNode( p_1, slot_1 );
+			appendNode( text_3, p_1 );
+		},
+
+		update: noop,
+
+		unmount: function () {
+			detachNode( div );
+		},
+
+		destroy: noop
+	};
+}
+
+class SvelteComponent extends HTMLElement {
+	constructor(options = {}) {
+		super();
+		this.options = options;
+		this._state = options.data || {};
+
+		this._observers = {
+			pre: Object.create( null ),
+			post: Object.create( null )
+		};
+
+		this._handlers = Object.create( null );
+
+		this._root = options._root || this;
+		this._yield = options._yield;
+		this._bind = options._bind;
+
+		this._fragment = create_main_fragment( this._state, this );
+
+		if ( !options._root ) {
+			this._fragment.create();
+			this._fragment.mount( this.attachShadow({ mode: 'open' }), null );
+		}
+	}
+
+	static get observedAttributes() {
+		return [];
+	}
+
+
+
+	attributeChangedCallback ( attr, oldValue, newValue ) {
+		this.set({ [attr]: newValue });
+	}
+}
+
+customElements.define('custom-element', SvelteComponent);
+
+assign( SvelteComponent.prototype, proto );
+
+export default SvelteComponent;
\ No newline at end of file
diff --git a/test/js/samples/custom-element-slot/input.html b/test/js/samples/custom-element-slot/input.html
new file mode 100644
index 0000000000..7a8e47c7ee
--- /dev/null
+++ b/test/js/samples/custom-element-slot/input.html
@@ -0,0 +1,15 @@
+<div>
+	<slot>
+		<p>default fallback content</p>
+	</slot>
+
+	<slot name='foo'>
+		<p>foo fallback content</p>
+	</slot>
+</div>
+
+<script>
+	export default {
+		tag: 'custom-element'
+	};
+</script>
\ No newline at end of file