`ERROR: no spiders found` when running tests

I'm trying to use the library for the first time. This is the directory hierarchy for my project:

├── LICENSE
├── README.md
├── requirements.txt
├── scrapper
│   ├── database.py
│   ├── __init__.py
│   ├── items.py
│   ├── middlewares.py
│   ├── pipelines.py
│   ├── settings.py
│   ├── spiders
│   │   ├── angeloni.py
│   │   ├── bistek.py
│   │   ├── hippo.py
│   │   └── __init__.py
│   └── utils.py
├── scrapy.cfg
├── setup.py
└── tests
    ├── __init__.py
    ├── items.py
    └── spiders.py

And this is the content of my scrapy.cfg file:

[settings]
default = scrapper.settings

[test]
root = tests
settings = scrapper.settings

[deploy]
#url = http://localhost:6800/
project = scrapper

But when I try to use the command scrapy-test at the root directory, I receive the following message:

ERROR: no spiders found

Is this a problem with my scrapy.cfg file?