diff --git a/core/src/test/java/ImageNodeTest.java b/core/src/test/java/ImageNodeTest.java
index bc50636..fdbb5ec 100644
--- a/core/src/test/java/ImageNodeTest.java
+++ b/core/src/test/java/ImageNodeTest.java
@@ -21,6 +21,6 @@
 	public void testToString() {
 		PImage aNode = new PImage(new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB));
 		aNode.getFullBoundsReference();
-		System.out.println(aNode.toString());
+		assertNotNull(aNode.toString());
 	}
 }
diff --git a/core/src/test/java/NodeTest.java b/core/src/test/java/NodeTest.java
index a6cd08e..413c627 100644
--- a/core/src/test/java/NodeTest.java
+++ b/core/src/test/java/NodeTest.java
@@ -197,7 +197,7 @@
 		d.addChild(e);
 		e.addChild(f);
 		
-		System.out.println(a.toString());
+		assertNotNull(a.toString());
 	}
 	
 	public void testRecursiveLayout() {
diff --git a/core/src/test/java/TextNodeTest.java b/core/src/test/java/TextNodeTest.java
index 324ca1f..2afa59f 100644
--- a/core/src/test/java/TextNodeTest.java
+++ b/core/src/test/java/TextNodeTest.java
@@ -35,6 +35,6 @@
 	public void testToString() {
 		PText t = new PText();
 		t.setText("hello world");
-		System.out.println(t.toString());
+		assertNotNull(t.toString());
 	}
 }
diff --git a/core/src/test/java/TransformActivityTest.java b/core/src/test/java/TransformActivityTest.java
index ef78be4..30c2c24 100644
--- a/core/src/test/java/TransformActivityTest.java
+++ b/core/src/test/java/TransformActivityTest.java
@@ -9,6 +9,7 @@
 	}
 	
 	public void testToString() {
-		System.out.println(new PTransformActivity(1000, 0, null).toString());
+		PTransformActivity transformActivity = new PTransformActivity(1000, 0, null);
+		assertNotNull(transformActivity.toString());
 	}
 }
diff --git a/core/src/test/java/ZoomEventHandlerTest.java b/core/src/test/java/ZoomEventHandlerTest.java
index 28c7a1f..b344f66 100644
--- a/core/src/test/java/ZoomEventHandlerTest.java
+++ b/core/src/test/java/ZoomEventHandlerTest.java
@@ -9,6 +9,7 @@
 	}
 	
 	public void testToString() {
-		System.out.println(new PZoomEventHandler().toString());
+		PZoomEventHandler zoomEventHandler = new PZoomEventHandler();
+		assertNotNull(zoomEventHandler.toString());
 	}
 }