server_test, ibus_test and xim_adapter_test each ran their own copy of
the same alt loop that stands in for imthread, and two of them had
private checkstr/checkenginepreedit variants. test_util.c now provides
Pump (trace, optional hold on a chosen op, stop) in its own proc so a
test may block in socket I/O while the engine runs, and test.h declares
the engine hooks once; every .c includes dat.h and fn.h itself as the
rest of the tree does. server_test's three copies of fixture setup and
teardown became serverbegin/serverend.
font.c exported three wrappers for one function, and the fit == -1 mode
existed only for the tests; textdraw() takes fit and colour. win.c
tested the empty picture in the thread and again in winshow, interned
two atoms by hand next to getatom(), kept a consumer-side drain that the
producer's already guarantees never finds anything, zeroed ten globals
before returning from the only thread that read them, and re-checked
sizes that resizebacking had just established. The page marker is laid
out once and drawn from the layout instead of being recomputed.
