bpo-36096: IDLE: Refactor class variables in colorizer (GH-12002) (GH-12075)

(cherry picked from commit ed1deb0719f0ac1b08a374e30ad26a701d4d51a2)

Co-authored-by: Cheryl Sabella <cheryl.sabella@gmail.com>

3 files changed, 58 insertions, 21 deletions

diff --git a/Lib/idlelib/colorizer.py b/Lib/idlelib/colorizer.py
index 57942e8a7ca..fd13281fb29 100644
--- a/Lib/idlelib/colorizer.py
+++ b/Lib/idlelib/colorizer.py
@@ -55,26 +55,35 @@ def color_config(text):
 class ColorDelegator(Delegator):
     """Delegator for syntax highlighting (text coloring).
 
-    Class variables:
-        after_id: Identifier for scheduled after event.
+    Instance variables:
+        delegate: Delegator below this one in the stack, meaning the
+                one this one delegates to.
+
+        Used to track state:
+        after_id: Identifier for scheduled after event, which is a
+                timer for colorizing the text.
         allow_colorizing: Boolean toggle for applying colorizing.
         colorizing: Boolean flag when colorizing is in process.
         stop_colorizing: Boolean flag to end an active colorizing
                 process.
         close_when_done: Widget to destroy after colorizing process
                 completes (doesn't seem to be used by IDLE).
-
-    Instance variables:
-        delegate: Delegator below this one in the stack, meaning the
-                one this one delegates to.
     """
 
     def __init__(self):
         Delegator.__init__(self)
+        self.init_state()
         self.prog = prog
         self.idprog = idprog
         self.LoadTagDefs()
 
+    def init_state(self):
+        "Initialize variables that track colorizing state."
+        self.after_id = None
+        self.allow_colorizing = True
+        self.stop_colorizing = False
+        self.colorizing = False
+
     def setdelegate(self, delegate):
         """Set the delegate for this instance.
 
@@ -134,11 +143,6 @@ class ColorDelegator(Delegator):
         self.delegate.delete(index1, index2)
         self.notify_range(index1)
 
-    after_id = None
-    allow_colorizing = True
-    stop_colorizing = False
-    colorizing = False
-
     def notify_range(self, index1, index2=None):
         "Mark text changes for processing and restart colorizing, if active."
         self.tag_add("TODO", index1, index2)
diff --git a/Lib/idlelib/idle_test/test_colorizer.py b/Lib/idlelib/idle_test/test_colorizer.py
index 4ade5a149b4..c31c49236ca 100644
--- a/Lib/idlelib/idle_test/test_colorizer.py
+++ b/Lib/idlelib/idle_test/test_colorizer.py
@@ -100,7 +100,7 @@ class ColorConfigTest(unittest.TestCase):
         eq(text['inactiveselectbackground'], 'gray')
 
 
-class ColorDelegatorTest(unittest.TestCase):
+class ColorDelegatorInstantiationTest(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
@@ -108,25 +108,19 @@ class ColorDelegatorTest(unittest.TestCase):
         root = cls.root = Tk()
         root.withdraw()
         text = cls.text = Text(root)
-        cls.percolator = Percolator(text)
-        # Delegator stack = [Delagator(text)]
 
     @classmethod
     def tearDownClass(cls):
-        cls.percolator.redir.close()
-        del cls.percolator, cls.text
+        del cls.text
         cls.root.update_idletasks()
         cls.root.destroy()
         del cls.root
 
     def setUp(self):
         self.color = colorizer.ColorDelegator()
-        self.percolator.insertfilter(self.color)
-        # Calls color.setdelagate(Delagator(text)).
 
     def tearDown(self):
         self.color.close()
-        self.percolator.removefilter(self.color)
         self.text.delete('1.0', 'end')
         self.color.resetcache()
         del self.color
@@ -134,12 +128,50 @@ class ColorDelegatorTest(unittest.TestCase):
     def test_init(self):
         color = self.color
         self.assertIsInstance(color, colorizer.ColorDelegator)
-        # The following are class variables.
+
+    def test_init_state(self):
+        # init_state() is called during the instantiation of
+        # ColorDelegator in setUp().
+        color = self.color
+        self.assertIsNone(color.after_id)
         self.assertTrue(color.allow_colorizing)
         self.assertFalse(color.colorizing)
+        self.assertFalse(color.stop_colorizing)
+
+
+class ColorDelegatorTest(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        requires('gui')
+        root = cls.root = Tk()
+        root.withdraw()
+        text = cls.text = Text(root)
+        cls.percolator = Percolator(text)
+        # Delegator stack = [Delegator(text)]
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.percolator.redir.close()
+        del cls.percolator, cls.text
+        cls.root.update_idletasks()
+        cls.root.destroy()
+        del cls.root
+
+    def setUp(self):
+        self.color = colorizer.ColorDelegator()
+        self.percolator.insertfilter(self.color)
+        # Calls color.setdelegate(Delegator(text)).
+
+    def tearDown(self):
+        self.color.close()
+        self.percolator.removefilter(self.color)
+        self.text.delete('1.0', 'end')
+        self.color.resetcache()
+        del self.color
 
     def test_setdelegate(self):
-        # Called in setUp.
+        # Called in setUp when filter is attached to percolator.
         color = self.color
         self.assertIsInstance(color.delegate, colorizer.Delegator)
         # It is too late to mock notify_range, so test side effect.
diff --git a/Misc/NEWS.d/next/IDLE/2019-02-23-17-53-53.bpo-36096.mN5Ly3.rst b/Misc/NEWS.d/next/IDLE/2019-02-23-17-53-53.bpo-36096.mN5Ly3.rst
new file mode 100644
index 00000000000..cd6f76e9ac2
--- /dev/null
+++ b/Misc/NEWS.d/next/IDLE/2019-02-23-17-53-53.bpo-36096.mN5Ly3.rst
@@ -0,0 +1 @@
+Refactor class variables to instance variables in colorizer.