diff --git a/src/reportengine/tests/test_executor.py b/src/reportengine/tests/test_executor.py
index a3c3b7b..925c28a 100644
--- a/src/reportengine/tests/test_executor.py
+++ b/src/reportengine/tests/test_executor.py
@@ -15,30 +15,34 @@
 from reportengine.dag import DAG
 from reportengine.utils import ChainMap
 from reportengine import namespaces
-from reportengine.resourcebuilder import (ResourceExecutor, CallSpec)
+from reportengine.resourcebuilder import ResourceExecutor, CallSpec
 
 """
 Define some simple functions that will be used as nodes in the DAG.
 """
 
+
 def node_1(param):
     print("Executing node_1")
     time.sleep(0.1)
     return "node_1_result: %s" % param
 
+
 def node_2_1(node_1_result):
     print("Executing node_2_1")
     time.sleep(0.2)
-    return node_1_result*2
+    return node_1_result * 2
+
 
 def node_2_2(node_1_result):
     print("Executing node_2_2")
     time.sleep(0.2)
-    return node_1_result*3
+    return node_1_result * 3
+
 
 def node_3(node_2_1_result, node_2_2_result, param=None):
     print("executing node_3")
-    return (node_2_1_result+node_2_2_result)*(param//2)
+    return (node_2_1_result + node_2_2_result) * (param // 2)
 
 
 class TestResourceExecutor(unittest.TestCase, ResourceExecutor):
@@ -57,46 +61,48 @@ def setUp(self):
                         node_3
 
         """
-        self.rootns = ChainMap({'param':4, 'inner': {}})
+        self.rootns = ChainMap({"param": 4, "inner": {}})
+
         def nsspec(x, beginning=()):
             ns = namespaces.resolve(self.rootns, beginning)
-            default_label =  '_default' + str(x)
+            default_label = "_default" + str(x)
             namespaces.push_nslevel(ns, default_label)
             return beginning + (default_label,)
 
         self.graph = DAG()
 
-        node_1_call = CallSpec(node_1, ('param',), 'node_1_result',
-                         nsspec(node_1))
+        node_1_call = CallSpec(node_1, ("param",), "node_1_result", nsspec(node_1))
 
-        node_2_1_call = CallSpec(node_2_1, ('node_1_result',), 'node_2_1_result',
-                         nsspec(node_2_1))
-
-        node_2_2_call = CallSpec(node_2_2, ('node_1_result',), 'node_2_2_result',
-                         nsspec(node_2_2))
-
-        node_3_call = CallSpec(node_3, ('node_2_1_result','node_2_2_result','param'), 'node_3_result',
-                         nsspec(node_3))
+        node_2_1_call = CallSpec(
+            node_2_1, ("node_1_result",), "node_2_1_result", nsspec(node_2_1)
+        )
 
+        node_2_2_call = CallSpec(
+            node_2_2, ("node_1_result",), "node_2_2_result", nsspec(node_2_2)
+        )
 
+        node_3_call = CallSpec(
+            node_3,
+            ("node_2_1_result", "node_2_2_result", "param"),
+            "node_3_result",
+            nsspec(node_3),
+        )
 
         self.graph.add_node(node_1_call)
         self.graph.add_node(node_2_1_call, inputs={node_1_call})
         self.graph.add_node(node_2_2_call, inputs={node_1_call})
         self.graph.add_node(node_3_call, inputs={node_2_1_call, node_2_2_call})
 
-
     def _test_ns(self, promise=False):
         """
         Asserts that the namespace contains the expected results.
         """
-        node_3_result = 'node_1_result: 4'*10
+        node_3_result = "node_1_result: 4" * 10
         namespace = self.rootns
         if promise:
-            self.assertEqual(namespace['node_3_result'].result(), node_3_result)
+            self.assertEqual(namespace["node_3_result"].result(), node_3_result)
         else:
-            self.assertEqual(namespace['node_3_result'], node_3_result)
-
+            self.assertEqual(namespace["node_3_result"], node_3_result)
 
     def test_seq_execute(self):
         """
@@ -113,5 +119,6 @@ def test_parallel_execute(self):
         self.execute_parallel()
         self._test_ns(promise=True)
 
-if __name__ =='__main__':
+
+if __name__ == "__main__":
     unittest.main()