Update TargetFiltering args for applying criteria (#7280)

Update the class to take the criteria in the constructor, and helper methods take the targets against which to apply said criteria.

From suggestion https://github.com/pantsbuild/pants/pull/7275\#discussion_r259554586

src/python/pants/build_graph/target_filter_subsystem.py

@@ -31,15 +31,14 @@ def register_options(cls, register):
 
   def apply(self, targets):
     exclude_tags = set(self.get_options().exclude_tags)
-    return TargetFiltering(targets, exclude_tags).apply_tag_blacklist()
+    return TargetFiltering(exclude_tags).apply_tag_blacklist(targets)
 
 
 class TargetFiltering(object):
   """Apply filtering logic against targets."""
 
-  def __init__(self, targets, exclude_tags):
-    self.targets = targets
+  def __init__(self, exclude_tags):
     self.exclude_tags = exclude_tags
 
-  def apply_tag_blacklist(self):
-    return [t for t in self.targets if not self.exclude_tags.intersection(t.tags)]
+  def apply_tag_blacklist(self, targets):
+    return [t for t in targets if not self.exclude_tags.intersection(t.tags)]

tests/python/pants_test/build_graph/test_target_filter_subsystem.py

@@ -41,21 +41,21 @@ def test_filtering_single_tag(self):
     b = self.make_target('b', tags=['skip-me'])
     c = self.make_target('c', tags=['tag1', 'skip-me'])
 
-    filtered_targets = TargetFiltering([a, b, c], {'skip-me'}).apply_tag_blacklist()
+    filtered_targets = TargetFiltering({'skip-me'}).apply_tag_blacklist([a, b, c])
     self.assertEqual([a], filtered_targets)
 
   def test_filtering_multiple_tags(self):
     a = self.make_target('a', tags=['tag1', 'skip-me'])
     b = self.make_target('b', tags=['tag1', 'tag2', 'skip-me'])
     c = self.make_target('c', tags=['tag2'])
 
-    filtered_targets = TargetFiltering([a, b, c], {'skip-me', 'tag2'}).apply_tag_blacklist()
+    filtered_targets = TargetFiltering({'skip-me', 'tag2'}).apply_tag_blacklist([a, b, c])
     self.assertEqual([], filtered_targets)
 
   def test_filtering_no_tags(self):
     a = self.make_target('a', tags=['tag1'])
     b = self.make_target('b', tags=['tag1', 'tag2'])
     c = self.make_target('c', tags=['tag2'])
 
-    filtered_targets = TargetFiltering([a, b, c], set()).apply_tag_blacklist()
+    filtered_targets = TargetFiltering(set()).apply_tag_blacklist([a, b, c])
     self.assertEqual([a, b, c], filtered_targets)