[lit] Do a better job at parsing unsupported tests.

[JDevlieghere]

Summary

When all the tests run by dotest are unsupported, it still reports RESULT: PASSED which we translate to success for lit. We can better report the status as unsupported when we see that there are unsupported tests but no passing tests. This will not affect the situation where there are failures or unexpected passes, because those report a non-zero exit code.

[xiaobai]

LGTM

[aprantl]

lldb/lit/Suite/lldbtest.py

105

'UNSUPPORTED:' in out + err ?

[JDevlieghere]

lldb/lit/Suite/lldbtest.py

105

Is that actually faster? If not I'd like to keep things consistent with the rest of the code above and below it.

[aprantl]

lldb/lit/Suite/lldbtest.py

105

I was optimizing for readability, not speed :-)
The principled solution would be to emit the same kind of junit XML output that lit produces or some other machine-readable format.

[JDevlieghere]

lldb/lit/Suite/lldbtest.py

105

I agree. It's on my todo list :-)

lldb/lit/Suite/lldbtest.py

def execute(self, test, litConfig):
             # Match FAIL but not XFAIL.
             for line in out.splitlines() + err.splitlines():
                 if line.startswith('FAIL:'):
                     return lit.Test.FAIL, out + err
 
             if 'XPASS:' in out or 'XPASS:' in err:
                 return lit.Test.XPASS, out + err
 
+        has_unsupported_tests = 'UNSUPPORTED:' in out or 'UNSUPPORTED:' in err
+        has_passing_tests = 'PASS:' in out or 'PASS:' in err
+        if has_unsupported_tests and not has_passing_tests:
+            return lit.Test.UNSUPPORTED, out + err
+
         passing_test_line = 'RESULT: PASSED'
         if passing_test_line not in out and passing_test_line not in err:
             msg = ('Unable to find %r in dotest output (exit code %d):\n\n%s%s'
                    % (passing_test_line, exitCode, out, err))
             return lit.Test.UNRESOLVED, msg
 
         return lit.Test.PASS, ''