support make check tests too

[cgwalters]

I was probably too agressive with OSTree in relying on only on https://wiki.gnome.org/GnomeGoals/InstalledTests . Let's take a look at a project which is doing both make check and installed, and handle both. glib/json-glib? Cockpit also has invested a lot in tests, should look there too.

[mbarnes]

Would it make sense to split things such that the installed tests exercise the CLI and the "make check" tests ring out the libostree API to a reasonable extent?

Also, Philip Withnall's uhttpmock might be useful for simulating fetches. We used that with E-D-S to some success. https://www.openhub.net/p/uhttpmock

[cgwalters]

A starting point in ostreedev/ostree#28

[cgwalters]

#76

[cgwalters]

WRT splitting installed/make check - I would prefer if installedtests was a superset of makecheck. For tests which don't access data, this is quite easy. It is harder if you need to read data, but newer GLib testing has some bits for that. I'm starting to use that in #76 .

[cgwalters]

#76