diff --git a/src/flake8/style_guide.py b/src/flake8/style_guide.py
index 24b87c3..07d9e06 100644
--- a/src/flake8/style_guide.py
+++ b/src/flake8/style_guide.py
@@ -126,7 +126,7 @@ class DecisionEngine(object):
 
         return Selected.Implicitly
 
-    def decision_for(self, code):
+    def more_specific_decision_for(self, code):
         # type: (Error) -> Decision
         select = find_first_match(code, self.all_selected)
         extra_select = find_first_match(code, self.extended_selected)
@@ -145,7 +145,7 @@ class DecisionEngine(object):
             return Decision.Ignored
         return Decision.Selected
 
-    def should_report_error(self, code):
+    def decision_for(self, code):
         # type: (str) -> Decision
         """Determine if the error code should be reported or ignored.
 
@@ -174,7 +174,7 @@ class DecisionEngine(object):
                   ignored is Ignored.Explicitly) or
                   (selected is Ignored.Implicitly and
                    ignored is Selected.Implicitly)):
-                decision = self.decision_for(code)
+                decision = self.more_specific_decision_for(code)
             elif (selected is Ignored.Implicitly or
                   ignored is Ignored.Explicitly):
                 decision = Decision.Ignored  # pylint: disable=R0204
@@ -187,7 +187,7 @@ class DecisionEngine(object):
 class StyleGuide(object):
     """Manage a Flake8 user's style guide."""
 
-    def __init__(self, options, listener_trie, formatter):
+    def __init__(self, options, listener_trie, formatter, decider=None):
         """Initialize our StyleGuide.
 
         .. todo:: Add parameter documentation.
@@ -196,39 +196,9 @@ class StyleGuide(object):
         self.listener = listener_trie
         self.formatter = formatter
         self.stats = statistics.Statistics()
-        self.decider = DecisionEngine(options)
+        self.decider = decider or DecisionEngine(options)
         self._parsed_diff = {}
 
-    def is_user_selected(self, code):
-        # type: (str) -> Union[Selected, Ignored]
-        """Determine if the code has been selected by the user.
-
-        :param str code:
-            The code for the check that has been run.
-        :returns:
-            Selected.Implicitly if the selected list is empty,
-            Selected.Explicitly if the selected list is not empty and a match
-            was found,
-            Ignored.Implicitly if the selected list is not empty but no match
-            was found.
-        """
-        return self.decider.was_selected(code)
-
-    def is_user_ignored(self, code):
-        # type: (str) -> Union[Selected, Ignored]
-        """Determine if the code has been ignored by the user.
-
-        :param str code:
-            The code for the check that has been run.
-        :returns:
-            Selected.Implicitly if the ignored list is empty,
-            Ignored.Explicitly if the ignored list is not empty and a match was
-            found,
-            Selected.Implicitly if the ignored list is not empty but no match
-            was found.
-        """
-        return self.decider.was_ignored(code)
-
     @contextlib.contextmanager
     def processing_file(self, filename):
         """Record the fact that we're processing the file's results."""
@@ -249,7 +219,7 @@ class StyleGuide(object):
         :param str code:
             The code for the check that has been run.
         """
-        return self.decider.should_report_error(code)
+        return self.decider.decision_for(code)
 
     def is_inline_ignored(self, error):
         # type: (Error) -> bool
diff --git a/tests/unit/test_decision_engine.py b/tests/unit/test_decision_engine.py
index 18aca78..aad0176 100644
--- a/tests/unit/test_decision_engine.py
+++ b/tests/unit/test_decision_engine.py
@@ -118,12 +118,12 @@ def test_was_selected_excludes_errors(select_list, error_code):
     (defaults.SELECT, defaults.IGNORE, 'E126', style_guide.Decision.Ignored),
     (defaults.SELECT, defaults.IGNORE, 'W391', style_guide.Decision.Selected),
 ])
-def test_should_report_error(select_list, ignore_list, error_code, expected):
+def test_decision_for(select_list, ignore_list, error_code, expected):
     """Verify we decide when to report an error."""
     decider = style_guide.DecisionEngine(create_options(select=select_list,
                                                         ignore=ignore_list))
 
-    assert decider.should_report_error(error_code) is expected
+    assert decider.decision_for(error_code) is expected
 
 
 @pytest.mark.parametrize(
@@ -164,9 +164,10 @@ def test_should_report_error(select_list, ignore_list, error_code, expected):
             style_guide.Decision.Selected),
     ]
 )
-def test_decision_for_logic(select, ignore, extend_select, enabled_extensions,
-                            error_code, expected):
-    """Verify the complicated logic of DecisionEngine.decision_for."""
+def test_more_specific_decision_for_logic(select, ignore, extend_select,
+                                          enabled_extensions, error_code,
+                                          expected):
+    """Verify the logic of DecisionEngine.more_specific_decision_for."""
     decider = style_guide.DecisionEngine(
         create_options(
             select=select, ignore=ignore,
@@ -175,4 +176,4 @@ def test_decision_for_logic(select, ignore, extend_select, enabled_extensions,
         ),
     )
 
-    assert decider.decision_for(error_code) is expected
+    assert decider.more_specific_decision_for(error_code) is expected