Analyze what heap consumes JUnit JavaFx

Is there any tool to check if I have a memory leak in my JUnit Test? Or is there a tool where I can check what the whole heap is used up?

My problem is this: I have many tests, but I just wrote new ones and now at some point I get java.lang.OutOfMemoryError: Java heap space. So I suppose I'm doing something wrong somewhere and I don't clean something up properly because the tests themselves (individually they are relatively lightly weighted) and always work with the GUI.

Im using Intellij, Java 11 and working with JavaFx.