[refs #263] Add initial transform code for text choices

Why:

- Transform tuples to include value and label properties

This change addresses the need by:

- Adding the text_choices transform file
- Integrating in the transforms init file
- Focusing on the predicate for the rule to trigger the transform

pylint_django/transforms/__init__.py

@@ -13,10 +13,10 @@
 
 import astroid
 
-from pylint_django.transforms import fields
+from pylint_django.transforms import fields, text_choices
 
 fields.add_transforms(astroid.MANAGER)
-
+text_choices.add_transforms(astroid.MANAGER)
 
 def _add_transform(package_name):
     def fake_module_builder():

pylint_django/transforms/text_choices.py

@@ -0,0 +1,70 @@
+from astroid import MANAGER, scoped_nodes, nodes, inference_tip
+
+from pylint_django import utils
+
+class_names = set()
+
+def is_tuple_in_text_choices(node):
+    # file_name = node.root().file
+    # if file_name not in file_names:
+    #     file_names.update({file_name})
+    #     import ipdb; ipdb.set_trace()
+    # else:
+    #     return False
+
+    if not (isinstance(node.parent, nodes.Assign)
+            or isinstance(node.parent, nodes.FunctionDef)) :
+        return False
+    if not isinstance(node.parent.parent, nodes.ClassDef):
+        return False
+    if "TextChoices" in [i.name for i in node.parent.parent.bases]:
+        import ipdb; ipdb.set_trace()
+
+    class_name = node.parent.parent.name
+    if class_name not in class_names:
+        class_names.update({class_name})
+        # import ipdb; ipdb.set_trace()
+    else:
+        return False
+
+    # if node.parent.parent.name == "SomeTextChoices":
+    #     import ipdb; ipdb.set_trace()
+    # else:
+    #     return False
+
+    # if node.parent.parent.parent.name in ["TextChoices", "SomeClass", "ChoicesMeta", "TextChoices"]:
+    #     import ipdb; ipdb.set_trace()
+    # else:
+    #     return False
+
+    # if node.root().file.endswith("enums.py"):
+    #     import ipdb; ipdb.set_trace()
+    # else:
+    #     return False
+
+    # try:
+    #     if node.root().file.endswith("model_enum.py"):
+    #         import ipdb; ipdb.set_trace()
+    # except:
+    #     import ipdb; ipdb.set_trace()
+    # if (node.parent.parent.name != "LazyObject"
+    #         and node.parent.parent.parent.name != "django.db.models.expressions"
+    #         and node.parent.parent.parent.name != "django.db.models.fields"):
+    #     import ipdb; ipdb.set_trace()
+
+    if isinstance(node.func, nodes.Attribute):
+        attr = node.func.attrname
+    elif isinstance(node.func, nodes.Name):
+        attr = node.func.name
+    else:
+        return False
+    return True
+
+
+def infer_key_classes(node, context=None):
+    pass
+
+
+def add_transforms(manager):
+    manager.register_transform(nodes.Call, inference_tip(infer_key_classes),
+                               is_tuple_in_text_choices)