adjust output to correspond to unittest

Generally speaking, expected occurrences are lowercase whereas
anything exceptional and worthy of notice is uppercase. Examples of
the former include tests passing, skips and expected failures;
examples of the latter include failures, errors and unexpected
successes.

Author: danchr

xmlrunner/result.py

@@ -313,7 +313,7 @@ def addSuccess(self, test):
         """
         self._save_output_data()
         self._prepare_callback(
-            self.infoclass(self, test), self.successes, 'OK', '.'
+            self.infoclass(self, test), self.successes, 'ok', '.'
         )
 
     @failfast
@@ -380,8 +380,10 @@ def addSkip(self, test, reason):
         self._save_output_data()
         testinfo = self.infoclass(
             self, test, self.infoclass.SKIP, reason)
+        testinfo.test_exception_name = 'skip'
+        testinfo.test_exception_message = reason
         self.skipped.append((testinfo, reason))
-        self._prepare_callback(testinfo, [], 'SKIP', 'S')
+        self._prepare_callback(testinfo, [], 'skip', 's')
 
     def addExpectedFailure(self, test, err):
         """
@@ -390,11 +392,11 @@ def addExpectedFailure(self, test, err):
         self._save_output_data()
 
         testinfo = self.infoclass(self, test, self.infoclass.ERROR, err)
-        testinfo.test_exception_name = 'ExpectedFailure'
-        testinfo.test_exception_message = 'EXPECTED FAILURE: {}'.format(testinfo.test_exception_message)
+        testinfo.test_exception_name = 'XFAIL'
+        testinfo.test_exception_message = 'expected failure: {}'.format(testinfo.test_exception_message)
 
         self.expectedFailures.append((testinfo, self._exc_info_to_string(err, test)))
-        self._prepare_callback(testinfo, [], 'EXPECTED FAILURE', 'X')
+        self._prepare_callback(testinfo, [], 'expected failure', 'x')
 
     @failfast
     def addUnexpectedSuccess(self, test):
@@ -407,11 +409,11 @@ def addUnexpectedSuccess(self, test):
         testinfo.outcome = self.infoclass.ERROR
         # But since we want to have error outcome, we need to provide additional fields:
         testinfo.test_exception_name = 'UnexpectedSuccess'
-        testinfo.test_exception_message = ('UNEXPECTED SUCCESS: This test was marked as expected failure but passed, '
+        testinfo.test_exception_message = ('Unexpected success: This test was marked as expected failure but passed, '
                                            'please review it')
 
-        self.unexpectedSuccesses.append(testinfo)
-        self._prepare_callback(testinfo, [], 'UNEXPECTED SUCCESS', 'U')
+        self.unexpectedSuccesses.append((testinfo, 'unexpected success'))
+        self._prepare_callback(testinfo, [], 'unexpected success', 'u')
 
     def printErrorList(self, flavour, errors):
         """