avocado.core.result: Handle incorrect number of total tests

When the total number of tests is lower than number of executed tests,
avocado reports incorrect number of tests. Let's increase the number of
tests in such case.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/result.py

@@ -137,7 +137,10 @@ class TestResult(object):
                                self.failed + self.warned +
                                self.skipped + self.interrupted)
         other_skipped_count = self.tests_total - valid_results_count
-        self.skipped += other_skipped_count
+        if other_skipped_count > 0:
+            self.skipped += other_skipped_count
+        else:
+            self.tests_total -= other_skipped_count
 
     def start_tests(self):
         """

selftests/unit/test_jsonresult.py

@@ -85,5 +85,20 @@ class JSONResultTest(unittest.TestCase):
         check_item("[skip]", res["skip"], 4)
         check_item("[total]", res["total"], 13)
 
+    def testNegativeStatus(self):
+        def check_item(name, value, exp):
+            self.assertEqual(value, exp, "Result%s is %s and not %s\n%s"
+                             % (name, value, exp, res))
+
+        self.test_result.tests_total = 0
+        self.test_result.start_test(self.test1)
+        self.test_result.check_test(self.test1.get_state())
+        self.test_result.end_tests()
+        res = json.loads(self.test_result.json)
+        check_item("[total]", res["total"], 1)
+        check_item("[skip]", res["skip"], 0)
+        check_item("[pass]", res["pass"], 1)
+
+
 if __name__ == '__main__':
     unittest.main()