You can move the views around by grabbing them, put the cursor on the tab hold it down and drag it to the destination move it around and you will see green rectangles or lines showing where the component will go. When you let go the view is moved. You can always move it back. If you can’t find a perspective, maybe you inadvertently closed it, you can get the perspective back by going to window and then Open Perspectives, click the one you want.
This is what it will look like after you move junit to be underneath the other views in the same column. You could have moved it someplace. If it turns greed then it is a valid drop area.