Javascript using AVA and JEST in same project

I have a project which currently uses "AVA" for testing but I also want to use "JEST".

I have installed both and the package.json part looks like this:

"test": "ava",
    "test:watch": "ava --watch",
    "test:verbose": "ava --verbose",

I now want to add JEST too so I added:

"testj": "jest",

So it now looks like this:

"test": "ava",
    "test:watch": "ava --watch",
    "test:verbose": "ava --verbose",
    "testj": "jest"

In theory I should be able to run:

npm testj to get JEST running right?

It just says: command not found.

Have I forgotten something? Can this not be done?

via JakeBrown777