While working on r370054, i've found it frustrating that the test output
was compeletely unhelpful in case of failures. Therefore I've decided to
improve that. In this I reuse the PExpectTest class, which was one of
our mechanisms for running pexpect tests, but which has gotten orhpaned
in the mean time.
I've replaced the existing send methods with a "expect" method, which
I've tried to design so that it has a similar interface to the expect
method in regular non-pexpect dotest tests (as it essentially does
something very similar). I've kept the ability to dump the transcript of
the pexpect communication to stdout in the "trace" mode, as that is a
very handy way to figure out what the test is doing. I've also removed
the "expect_string" method used in the existing tests -- I've found this
to be unhelpful because it hides the message that would be normally
displayed by the EOF exception. Although vebose, this message includes
some important information, like what strings we were searching for,
what were the last bits of lldb output, etc. I've also beefed up the
class to automatically disable the debug info test duplication, and
auto-skip tests when the host platform does not support pexpect.
This patch ports TestMultilineCompletion and TestIOHandlerCompletion to
the new class. It also deletes TestFormats as it is not testing anything
(definitely not formats) -- it used to test something at one point, but
then the testing code was commented out, and later deleted in (r356000).