Ignore teardown failure if it's caused by removing missing file or directory

[chying]

Summary

This is aiming to workaround this issue:
When test is decorated with expectedFlakey* and has teardown hook attached, the teardown hook will be added and executed twice,
the second execution will fail due to "missing file".

[vharron]

Maybe we should call teardown from expectedFlakey instead?

[tberghammer]

I agree that we should call a tear-down after each run of the test case because without it the 2 run might effect each other. Also the same is true for calling set-up before each run.

[chying]

Based on feedback, handle teardown and setup inside of expectedFlakey function.
Don't run retry if the test case is already marked as xfail or skip.

[tberghammer]

LGTM

test/unittest2/case.py

def run(self, result=None):
                     self._addSkip(result, str(e))
                 except Exception:
                     result.addError(self, sys.exc_info())
                 else:
                     success = True
 
                 try:
                     self.tearDown()
-                except Exception:
+                except Exception, e:
+                    # ignore teardown failure if it's caused by removing missing file or directory
+                    if isinstance(e, OSError) and "No such file or directory" in e.args:
+                        warnings.warn(sys.exc_info())
+                    else:
                         result.addError(self, sys.exc_info())
                         success = False
 
             cleanUpSuccess = self.doCleanups()
             success = success and cleanUpSuccess
             if success:
                 result.addSuccess(self)
         finally:
             result.stopTest(self)
             if orig_result is None: