The previous version of the plugin manager's method
get_remote_plugin_info() was suitable for installing missing
dependencies only. To make use of for installing new plugins and/or
available updates, it must be clear that we are requesting information
for the particular plugin version only, not "given or higher" version.
The patch improves the dependencies resolution in the plugin manager so
that the information about availability of the missing dependency is
included and can be displayed at the Plugins check screen during the
upgrade.
The actual loading of available updates info objects is moved back to
the plugin manager class. As we can now mockup the manager in unit
tests, this allows us to bypass the real \core\update\checker and have
unit tests for \core\plugininfo\base::available_updates().
We can now override the plugin manager's methods in the testable
subclass while still keeping the singleton behaviour of it. The change
makes use of late static binding.
David Mudrák