[Error] Excepción al acceder a BD en tests en docker

[AndresJR]

Tras levantar la aplicación con docker-compose, al intentar correr las pruebas con docker run ./manage.py test se devuelve un fallo que parece estar relacionado con la no accesibilidad del contenedor "db" para la base de datos. Copia del error:

/usr/local/lib/python3.8/site-packages/django/db/backends/postgresql/base.py:253: RuntimeWarning: Normally Django will use a connection to the 'postgres' database to avoid running initialization queries against the production database when it's not needed (for example, when running tests). Django was unable to create a connection to the 'postgres' database and will use the default database instead.
warnings.warn(
nosetests --verbosity=1
Creating test database for alias 'default'...
Traceback (most recent call last):
File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 216, in ensure_connection
self.connect()
File "/usr/local/lib/python3.8/site-packages/django/db/backends/base/base.py", line 194, in connect
self.connection = self.get_new_connection(conn_params)
File "/usr/local/lib/python3.8/site-packages/django/db/backends/postgresql/base.py", line 168, in get_new_connection
connection = Database.connect(**conn_params)
File "/usr/local/lib/python3.8/site-packages/psycopg2/init.py", line 126, in connect
conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError: could not translate host name "db" to address: Name does not resolve