Avoid calling libtool to link every single test case, by building just one
binary from all the sources.
This binary is then given the task of choosing tests to run (based on user
selection and individual test requirement), forking each test into its own
process and accumulating the results.
By keeping a static reference to the user font face, it is erroneously kept
alive during a call to cairo_debug_reset_static_data(). (A violation of
the caller's contract to ensure that no active reference to a cairo object
is held by the caller.)
In order to run under memfault, the framework is first extended to handle
running concurrent tests - i.e. multi-threading. (Not that this is a
requirement for memfault, instead it shares a common goal of storing
per-test data). To that end all the global data is moved into a per-test
context and the targets are adjusted to avoid overlap on shared, global
resources (such as output files and frame buffers). In order to preserve
the simplicity of the standard draw routines, the context is not passed
explicitly as a parameter to the routines, but is instead attached to the
cairo_t via the user_data.
For the masochist, to enable the tests to be run across multiple threads
simply set the environment variable CAIRO_TEST_NUM_THREADS to the desired
number.
In the long run, we can hope the need for memfault (runtime testing of
error paths) will be mitigated by static analysis. A promising candidate
for this task would appear to be http://hal.cs.berkeley.edu/cil/.
The init func does not actually need to draw anything, but having a cairo_t
similar to that passed to render_glyph is handy for computing font extents.
This is because cairo makes doing some things really hard (if not impossible)
without a cairo_t.
The user-font-proxy test case is a great example of how the added cairo_t
makes life much easier.
This way the same callback code can be used to render multiple different
glyph arrays. Change done for education purposes, otherwise doesn't
make any difference in the test.
