diff --git a/test/js/samples/collapses-text-around-comments/expected-bundle.js b/test/js/samples/collapses-text-around-comments/expected-bundle.js
index c6c7723883..59faec43c0 100644
--- a/test/js/samples/collapses-text-around-comments/expected-bundle.js
+++ b/test/js/samples/collapses-text-around-comments/expected-bundle.js
@@ -115,9 +115,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/computed-collapsed-if/expected-bundle.js b/test/js/samples/computed-collapsed-if/expected-bundle.js
index 35b70e4100..6e24c4c163 100644
--- a/test/js/samples/computed-collapsed-if/expected-bundle.js
+++ b/test/js/samples/computed-collapsed-if/expected-bundle.js
@@ -91,9 +91,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/each-block-changed-check/expected-bundle.js b/test/js/samples/each-block-changed-check/expected-bundle.js
index b5a15f5630..8aeafdeb12 100644
--- a/test/js/samples/each-block-changed-check/expected-bundle.js
+++ b/test/js/samples/each-block-changed-check/expected-bundle.js
@@ -124,9 +124,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/event-handlers-custom/expected-bundle.js b/test/js/samples/event-handlers-custom/expected-bundle.js
index 6019667c51..de76233275 100644
--- a/test/js/samples/event-handlers-custom/expected-bundle.js
+++ b/test/js/samples/event-handlers-custom/expected-bundle.js
@@ -109,9 +109,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/if-block-no-update/expected-bundle.js b/test/js/samples/if-block-no-update/expected-bundle.js
index 53cca6fa20..5c46a788ad 100644
--- a/test/js/samples/if-block-no-update/expected-bundle.js
+++ b/test/js/samples/if-block-no-update/expected-bundle.js
@@ -115,9 +115,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/if-block-simple/expected-bundle.js b/test/js/samples/if-block-simple/expected-bundle.js
index 9636f3d99a..723df41e99 100644
--- a/test/js/samples/if-block-simple/expected-bundle.js
+++ b/test/js/samples/if-block-simple/expected-bundle.js
@@ -115,9 +115,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/js/samples/non-imported-component/expected-bundle.js b/test/js/samples/non-imported-component/expected-bundle.js
index 04bd9f8588..1b29740949 100644
--- a/test/js/samples/non-imported-component/expected-bundle.js
+++ b/test/js/samples/non-imported-component/expected-bundle.js
@@ -103,9 +103,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
@@ -194,9 +197,13 @@ function SvelteComponent ( options ) {
 		this._fragment.mount( options.target, null );
 	}
 
-	callAll(this._beforecreate);
-	callAll(this._oncreate);
-	callAll(this._aftercreate);
+	if ( !options._root ) {
+		this._block = true;
+		callAll(this._beforecreate);
+		callAll(this._oncreate);
+		callAll(this._aftercreate);
+		this._block = false;
+	}
 }
 
 assign( SvelteComponent.prototype, proto );
diff --git a/test/js/samples/non-imported-component/expected.js b/test/js/samples/non-imported-component/expected.js
index 61c2cceee1..065ebc0a72 100644
--- a/test/js/samples/non-imported-component/expected.js
+++ b/test/js/samples/non-imported-component/expected.js
@@ -76,9 +76,13 @@ function SvelteComponent ( options ) {
 		this._fragment.mount( options.target, null );
 	}
 
-	callAll(this._beforecreate);
-	callAll(this._oncreate);
-	callAll(this._aftercreate);
+	if ( !options._root ) {
+		this._block = true;
+		callAll(this._beforecreate);
+		callAll(this._oncreate);
+		callAll(this._aftercreate);
+		this._block = false;
+	}
 }
 
 assign( SvelteComponent.prototype, proto );
diff --git a/test/js/samples/onrender-onteardown-rewritten/expected-bundle.js b/test/js/samples/onrender-onteardown-rewritten/expected-bundle.js
index 02ccad5144..61de8b261e 100644
--- a/test/js/samples/onrender-onteardown-rewritten/expected-bundle.js
+++ b/test/js/samples/onrender-onteardown-rewritten/expected-bundle.js
@@ -91,9 +91,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
@@ -159,7 +162,10 @@ function SvelteComponent ( options ) {
 		this._fragment.create();
 		this._fragment.mount( options.target, null );
 	}
-	callAll(this._oncreate);
+
+	if ( !options._root ) {
+		callAll(this._oncreate);
+	}
 }
 
 assign( SvelteComponent.prototype, proto );
diff --git a/test/js/samples/onrender-onteardown-rewritten/expected.js b/test/js/samples/onrender-onteardown-rewritten/expected.js
index ff00f93928..1a1c10f7d6 100644
--- a/test/js/samples/onrender-onteardown-rewritten/expected.js
+++ b/test/js/samples/onrender-onteardown-rewritten/expected.js
@@ -51,7 +51,10 @@ function SvelteComponent ( options ) {
 		this._fragment.create();
 		this._fragment.mount( options.target, null );
 	}
-	callAll(this._oncreate);
+
+	if ( !options._root ) {
+		callAll(this._oncreate);
+	}
 }
 
 assign( SvelteComponent.prototype, proto );
diff --git a/test/js/samples/use-elements-as-anchors/expected-bundle.js b/test/js/samples/use-elements-as-anchors/expected-bundle.js
index ec2ceaf4af..8a42c00e2a 100644
--- a/test/js/samples/use-elements-as-anchors/expected-bundle.js
+++ b/test/js/samples/use-elements-as-anchors/expected-bundle.js
@@ -115,9 +115,12 @@ function on(eventName, handler) {
 
 function set(newState) {
 	this._set(assign({}, newState));
+	if (this._root._block) return;
+	this._root._block = true;
 	callAll(this._root._beforecreate);
 	callAll(this._root._oncreate);
 	callAll(this._root._aftercreate);
+	this._root._block = false;
 }
 
 function callAll(fns) {
diff --git a/test/runtime/index.js b/test/runtime/index.js
index 16d5820f0b..dea60082a3 100644
--- a/test/runtime/index.js
+++ b/test/runtime/index.js
@@ -137,10 +137,9 @@ describe("runtime", () => {
 						throw err;
 					}
 
+					let usedObjectAssign = false;
 					Object.assign = () => {
-						throw new Error(
-							"cannot use Object.assign in generated code, as it is not supported everywhere"
-						);
+						usedObjectAssign = true;
 					};
 
 					global.window = window;
@@ -182,14 +181,18 @@ describe("runtime", () => {
 						assert.htmlEqual(target.innerHTML, config.html);
 					}
 
-					Object.assign = Object_assign;
-
 					if (config.test) {
 						config.test(assert, component, target, window, raf);
 					} else {
 						component.destroy();
 						assert.equal(target.innerHTML, "");
 					}
+
+					if (usedObjectAssign) {
+						throw new Error(
+							"cannot use Object.assign in generated code, as it is not supported everywhere"
+						);
+					}
 				})
 				.catch(err => {
 					Object.assign = Object_assign;