Question: How do I check if a component is not present, i.e. that a specific component has not been rendered?

Answer: 
You can use enzymes [`contains`](http://airbnb.io/enzyme/docs/api/ShallowWrapper/contains.html) to check if the component was rendered:

```
expect(component.contains(<ComponentName />)).toBe(false)

```
If you are using react-testing-library, then this also will work:

```
expect(component.queryByText("Text I care about").toBeNull());
expect(within(component).queryByText("Text I care about")).toBeNull();

```

Note: In my case, I needed to use `queryBy*` because it doesn´t error out when the text element (that contains the text: Text I care about) does not exist. Therefore, I could evaluate whether there is an existence of a text component or not.