oeqa: Add selftest parallelisation support

This allows oe-selftest to take a -j option which specifies how much test
parallelisation to use. Currently this is "module" based with each module
being split and run in a separate build directory. Further splitting could
be done but this seems a good compromise between test setup and parallelism.

You need python-testtools and python-subunit installed to use this but only
when the -j option is specified.

See notes posted to the openedmbedded-architecture list for more details
about the design choices here.

Some of this functionality may make more sense in the oeqa core ultimately.

(From OE-Core rev: 326ababfd620ae5ea29bf486b9d68ba3d60cad30)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/core/context.py

@@ -58,14 +58,20 @@ class OETestContext(object):
                 modules_required, filters)
         self.suites = self.loader.discover()
 
-    def runTests(self, skips=[]):
+    def runTests(self, processes=None, skips=[]):
         self.runner = self.runnerClass(self, descriptions=False, verbosity=2, buffer=True)
 
         # Dinamically skip those tests specified though arguments
         self.skipTests(skips)
 
         self._run_start_time = time.time()
-        result = self.runner.run(self.suites)
+        if processes:
+            from oeqa.core.utils.concurrencytest import ConcurrentTestSuite
+
+            concurrent_suite = ConcurrentTestSuite(self.suites, processes)
+            result = self.runner.run(concurrent_suite)
+        else:
+            result = self.runner.run(self.suites)
         self._run_end_time = time.time()
 
         return result