CT-710 fix test graph selection (#5324)

* Fix test_graph_selection so it can run separately

* Changie

.changes/unreleased/Under the Hood-20220601-112648.yaml

@@ -0,0 +1,7 @@
+kind: Under the Hood
+body: Fix unit test test_graph_selection
+time: 2022-06-01T11:26:48.725831-04:00
+custom:
+ Author: gshank
+ Issue: "5323"
+ PR: "5324"

core/dbt/graph/selector_spec.py

@@ -2,7 +2,7 @@
 import re
 from abc import ABCMeta, abstractmethod
 from dataclasses import dataclass
-from dbt.dataclass_schema import StrEnum
+from dbt.dataclass_schema import StrEnum, dbtClassMixin
 
 from typing import Set, Iterator, List, Optional, Dict, Union, Any, Iterable, Tuple
 from .graph import UniqueId
@@ -169,7 +169,7 @@ def from_single_spec(
  )
 
 
-class BaseSelectionGroup(Iterable[SelectionSpec], metaclass=ABCMeta):
+class BaseSelectionGroup(dbtClassMixin, Iterable[SelectionSpec], metaclass=ABCMeta):
  def __init__(
  self,
  components: Iterable[SelectionSpec],

test/unit/test_graph_selection.py

@@ -11,6 +11,13 @@
 
 import networkx as nx
 
+from dbt import flags
+
+from argparse import Namespace
+from dbt.contracts.project import UserConfig
+
+flags.set_from_args(Namespace(), UserConfig())
+
 
 def _get_graph():
  integer_graph = nx.balanced_tree(2, 2, nx.DiGraph())