John Cai [off-list ref] writes:

Let me see if I understand you. What I'm hearing is that it's hard to test a git
processes (A) that read/write from/to pipes without knowing exactly how (A) will
behave. By necessity, the test logic will have embedded some logic in it that
assumes certain behavior from (A), which might or might not be the case.

This can lead to a hanging test if, say, it is waiting around for (A) to output
data when due to a bug in the code, it never does. Did I get that right?

Exactly.  And we've seen such tests that are designed to hang, when
they detect bugs, which made us very unhappy and we fixed them not
to hang but reliably fail.  Otherwise, such tests weren't very
useful in unattended CI environment, which we do not want to wait
for 3 hours to timeout and leave later steps in the same script
untested.

Thanks.