Scenarios in acceptance tests must be independent one of each other.
That is, the execution of one scenario can not affect the execution of
another scenario, nor it can depend on the result of the execution of a
different scenario. Each scenario must be isolated and self-contained.
As the acceptance tests are run against a Nextcloud server the server
must be in a known and predefined initial state each time a scenario
begins.
The NextcloudTestServerContext is introduced to automatically set up the
Nextcloud test server for each scenario.
This can be achieved using Docker containers. Before an scenario begins
a new Docker container with a Nextcloud server is run; the scenario is
then run against the server provided by the container. When the scenario
ends the container is destroyed. As long as the Nextcloud server uses
local data storage each scenario is thus isolated from the rest.
The NextcloudTestServerContext also notifies its sibling RawMinkContexts
about the base URL of the Nextcloud test server being used in each
scenario.
Although it uses the Behat context system, NextcloudTestServerContext is
not really part of the acceptance tests, but a provider of core features
needed by them; it can be seen as part of a Nextcloud acceptance test
library. Therefore, those classes are stored in the "core" directory
instead of the "bootstrap" directory. Besides its own (quite limited)
autoload configuration, Behat also uses the Composer autoloader, so the
"core" directory has to be added there for its classes to be found by
Behat.
Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>