Fail if no tests were successfully executed

This commit adds another sanity check to ensure we didn't have a test
run with just skipped tests.

Change-Id: Ie4bd185c209d9e9230ca8a3f54e8a433e82d9c14

os_testr/subunit_trace.py

@@ -354,6 +354,12 @@ def main():
         print_fails(sys.stdout)
     if not args.no_summary:
         print_summary(sys.stdout, elapsed_time)
+
+    # NOTE(mtreinish): Ideally this should live in testtools streamSummary
+    # this is just in place until the behavior lands there (if it ever does)
+    if count_tests('status', '^success$') == 0:
+        print("\nNo tests were successful during the run")
+        exit(1)
     exit(0 if summary.wasSuccessful() else 1)
 
 

os_testr/tests/test_subunit_trace.py

@@ -14,6 +14,8 @@
 # under the License.
 
 from datetime import datetime as dt
+import os
+import subprocess
 
 from ddt import data
 from ddt import ddt
@@ -59,3 +61,21 @@ class TestSubunitTrace(base.TestCase):
         }
         with patch.dict(subunit_trace.RESULTS, patched_res, clear=True):
             self.assertEqual(subunit_trace.run_time(), expected_result)
+
+    def test_return_code_all_skips(self):
+        skips_stream = os.path.join(
+            os.path.dirname(os.path.abspath(__file__)),
+            'sample_streams/all_skips.subunit')
+        p = subprocess.Popen(['subunit-trace'], stdin=subprocess.PIPE)
+        with open(skips_stream, 'rb') as stream:
+            p.communicate(stream.read())
+        self.assertEqual(1, p.returncode)
+
+    def test_return_code_normal_run(self):
+        regular_stream = os.path.join(
+            os.path.dirname(os.path.abspath(__file__)),
+            'sample_streams/successful.subunit')
+        p = subprocess.Popen(['subunit-trace'], stdin=subprocess.PIPE)
+        with open(regular_stream, 'rb') as stream:
+            p.communicate(stream.read())
+        self.assertEqual(0, p.returncode)