add explicit exit code 1 if tests fail

tests/run_all_tests.py

@@ -11,4 +11,7 @@ if __name__ == '__main__':
     test_suite.addTests(all_tests)
 
     runner = unittest.TextTestRunner(verbosity=2)
-    runner.run(test_suite)
+    result = runner.run(test_suite)
+
+    if not result.wasSuccessful():
+        exit(1)

tests/test_determinist.py

@@ -99,4 +99,7 @@ if __name__ == '__main__':
     )
 
     runner = unittest.TextTestRunner(verbosity=2)
-    runner.run(test_suite)
+    result = runner.run(test_suite)
+
+    if not result.wasSuccessful():
+        exit(1)

tests/test_probabilist.py

@@ -100,4 +100,7 @@ if __name__ == '__main__':
     )
 
     runner = unittest.TextTestRunner(verbosity=2)
-    runner.run(test_suite)
+    result = runner.run(test_suite)
+
+    if not result.wasSuccessful():
+        exit(1)