[lldb-dev] Questions about the LLDB testsuite and improving its reliability

[Adrian Prantl via lldb-dev]

Hi lldb-dev!

I've been investigating some spurious LLDB test suite failures on http://green.lab.llvm.org/green/ that had to do with build artifacts from previous runs lying around in the test directories and this prompted me to ask a couple of general noob questions about the LLDB testsuite.

My understanding is that all execution tests are compiled using using `make` in-tree. I.e.: the test driver (dotest.py) effectively executes something equivalent to `cd $srcdir/packages/.../mytest && make`. And it does this in a serial fashion for all configurations (dwarf, dSYM, dwo, ...) and relies on the `clean` target to be implemented correctly.

I don't understand all the design decisions that went into the LLDB testsuite, but my naive intuition tells me that this is sub-optimal (because of the serialization of the configurations) and dangerous (because it relies on make clean being implemented correctly). It seems to me that a better approach would be to create a separate build directory for each test variant and then invoke something like `cd $builddir/test/mytest.dwarf && make -C $srcdir/packages/.../mytest`. This way all configurations can build in parallel, and we can simply nuke the build directory afterwards and this way get rid of all custom implementations of the `clean` target.

- Is this already possible, and/or am I misunderstanding how it works?
- Would this be a goal that is worthwhile to pursue?
- Is there a good reason why we are not already doing it this way?

thanks,
adrian