Flake8 refactor node selector

core/dbt/graph/selector.py

@@ -9,7 +9,7 @@
 from dbt.logger import GLOBAL_LOGGER as logger
 from dbt.utils import coalesce
 from dbt.node_types import NodeType
-from dbt.exceptions import RuntimeException,InternalException, warn_or_error
+from dbt.exceptions import RuntimeException, InternalException, warn_or_error
 
 SELECTOR_PARENTS = '+'
 SELECTOR_CHILDREN = '+'
@@ -81,7 +81,10 @@ def __str__(self):
 
 def alert_non_existance(raw_spec, nodes):
     if len(nodes) == 0:
-        warn_or_error(f"The selector '{str(raw_spec)}' does not match any nodes and will be ignored")
+        warn_or_error(
+            f"The selector '{str(raw_spec)}' does not match any nodes and will"
+            f" be ignored"
+        )
 
 
 def split_specs(node_specs: Iterable[str]):
@@ -385,31 +388,47 @@ def get_nodes_from_spec(self, graph, spec):
 
         return collected
 
-    def get_nodes_from_multiple_specs(self, graph, specs, selected_nodes=None, check_existence=False, exclude=False):
-        selected_nodes: Set[str] = coalesce(selected_nodes, set())
+    def get_nodes_from_multiple_specs(
+            self,
+            graph: Graph,
+            specs: Iterable[str],
+            nodes: Set[str] = None,
+            check_existence=False,
+            exclude=False
+    ):
+        selected_nodes: Set[str] = coalesce(nodes, set())
         operator = set.difference_update if exclude else set.update
 
         for raw_spec in split_specs(specs):
             spec = SelectionCriteria(raw_spec)
-            included_nodes = self.get_nodes_from_spec(graph, spec)
+            nodes = self.get_nodes_from_spec(graph, spec)
 
             if check_existence:
-                alert_non_existance(raw_spec, included_nodes)
+                alert_non_existance(raw_spec, nodes)
 
-            operator(selected_nodes, included_nodes)
+            operator(selected_nodes, nodes)
 
         return selected_nodes
 
     def select_nodes(self, graph, raw_include_specs, raw_exclude_specs):
+        raw_exclude_specs = coalesce(raw_exclude_specs, [])
         check_existance = True
 
         if not raw_include_specs:
             check_existance = False
             raw_include_specs = ['fqn:*', 'source:*']
 
-        selected_nodes = self.get_nodes_from_multiple_specs(graph, raw_include_specs, check_existence=check_existance)
-        selected_nodes = self.get_nodes_from_multiple_specs(graph, raw_exclude_specs, selected_nodes=selected_nodes,
-                                                            exclude=True)
+        selected_nodes = self.get_nodes_from_multiple_specs(
+            graph,
+            raw_include_specs,
+            check_existence=check_existance
+        )
+        selected_nodes = self.get_nodes_from_multiple_specs(
+            graph,
+            raw_exclude_specs,
+            nodes=selected_nodes,
+            exclude=True
+        )
 
         return selected_nodes