Rails: rake db:create:all fails to connect to PostgreSQL database

@Riateche: Finally, I saw that the database configuration for test environment misses the explicit settings for host and port. After I added the settings to the test environment, I was able to run the command bundle exec rake db:create:all successfully.
I must say, I do not like that they suggest those settings for the development enviroment, but did not add them for the other environments. That makes it very likely to miss them, as I proofed.

test:
  adapter: postgresql
  encoding: unicode
  database: my_test_app_test
  pool: 5
  username: johndoe
  password: password
  host: localhost
  port: 5433