diff --git a/.travis.yml b/.travis.yml
index 2c9f0f0df..c9f601144 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,7 @@ before_install: pip install --upgrade pip setuptools six
 install: pip install black flake8
 notifications:
     webhooks: https://www.travisbuddy.com/
+    on_success: never
 before_script:
   - black --check . || true
   - flake8 --ignore=E203,W503 --max-complexity=25 --max-line-length=120 --statistics --count .
diff --git a/greedy_method/test_knapsack.py b/greedy_method/test_knapsack.py
index 8f8107bc7..9d556d2d2 100644
--- a/greedy_method/test_knapsack.py
+++ b/greedy_method/test_knapsack.py
@@ -67,7 +67,9 @@ class TestClass(unittest.TestCase):
         # profit = [10, 20, 30, 40, 50]
         # weight = [2, 4, 6, 8, 10, 12]
         # max_weight = 100
-        self.assertRaisesRegex(IndexError, "The length of profit and weight must be same.")
+        self.assertRaisesRegex(
+            IndexError, "The length of profit and weight must be same."
+        )
 
 
 if __name__ == "__main__":