Implemented new check consider-using-from-import (pylint-dev#4491)

ChangeLog

@@ -67,6 +67,11 @@ modules are added.
 
   Closes #4470
 
+* New checker``consider-using-from-import``. Emitted when a submodule/member of a package is imported and aliased
+  with the same name.
+
+  Closes #2309
+
 
 What's New in Pylint 2.8.2?
 ===========================

doc/whatsnew/2.9.rst

@@ -23,6 +23,8 @@ New checkers
 * ``unnecessary-dict-index-lookup``: Emitted when iterating over dictionary items
   (key-value pairs) and accessing the value by index lookup.
 
+* ``consider-using-from-import``: Emitted when a submodule/member of a package is imported and aliased with the same name.
+
 Other Changes
 =============
 

pylint/checkers/imports.py

@@ -48,7 +48,7 @@
 import os
 import sys
 from distutils import sysconfig
-from typing import Dict, List
+from typing import Dict, List, Union
 
 import astroid
 
@@ -236,6 +236,14 @@ def _make_graph(filename: str, dep_info: Dict[str, List[str]], sect: VNode, gtyp
         "cyclic-import",
         "Used when a cyclic import between two or more modules is detected.",
     ),
+    "R0402": (
+        "Use 'from %s import %s' instead",
+        "consider-using-from-import",
+        "Emitted when a submodule/member of a package is imported and "
+        "aliased with the same name. "
+        "E.g., instead of ``import pandas.DataFrame as DataFrame`` use "
+        "``from pandas import DataFrame``",
+    ),
     "W0401": (
         "Wildcard import %s",
         "wildcard-import",
@@ -865,22 +873,28 @@ def _check_preferred_module(self, node, mod_path):
                 args=(self.preferred_modules[mod_path], mod_path),
             )
 
-    def _check_import_as_rename(self, node):
+    def _check_import_as_rename(
+        self, node: Union[astroid.Import, astroid.ImportFrom]
+    ) -> None:
         names = node.names
         for name in names:
             if not all(name):
                 return
 
-            real_name = name[0]
-            splitted_packages = real_name.rsplit(".")
-            real_name = splitted_packages[-1]
-            imported_name = name[1]
-            # consider only following cases
-            # import x as x
-            # and ignore following
-            # import x.y.z as z
-            if real_name == imported_name and len(splitted_packages) == 1:
+            splitted_packages = name[0].rsplit(".", maxsplit=1)
+            import_name = splitted_packages[-1]
+            aliased_name = name[1]
+            if import_name != aliased_name:
+                continue
+
+            if len(splitted_packages) == 1:
                 self.add_message("useless-import-alias", node=node)
+            elif len(splitted_packages) == 2:
+                self.add_message(
+                    "consider-using-from-import",
+                    node=node,
+                    args=(splitted_packages[0], import_name),
+                )
 
     def _check_reimport(self, node, basename=None, level=None):
         """check if the import is necessary (i.e. not already done)"""

tests/extensions/test_empty_comment.py

@@ -2,7 +2,7 @@
 
 import pytest
 
-import pylint.extensions.empty_comment as empty_comment
+from pylint.extensions import empty_comment
 
 
 @pytest.fixture(scope="module")

tests/functional/u/useless/useless-import-alias.py → tests/functional/i/import_aliasing.py

@@ -1,9 +1,13 @@
 # pylint: disable=unused-import, missing-docstring, invalid-name, reimported, import-error, wrong-import-order, no-name-in-module, relative-beyond-top-level
+# Functional tests for import aliasing
+# 1. useless-import-alias
+# 2. consider-using-from-import
+
 from collections import OrderedDict as OrderedDict # [useless-import-alias]
 from collections import OrderedDict as o_dict
-import os.path as path
+import os.path as path  # [consider-using-from-import]
 import os.path as p
-import foo.bar.foobar as foobar
+import foo.bar.foobar as foobar  # [consider-using-from-import]
 import os
 import os as OS
 from sys import version

tests/functional/i/import_aliasing.txt

@@ -0,0 +1,9 @@
+useless-import-alias:6:0::Import alias does not rename original package
+consider-using-from-import:8:0::Use 'from os import path' instead
+consider-using-from-import:10:0::Use 'from foo.bar import foobar' instead
+useless-import-alias:14:0::Import alias does not rename original package
+useless-import-alias:17:0::Import alias does not rename original package
+useless-import-alias:18:0::Import alias does not rename original package
+useless-import-alias:20:0::Import alias does not rename original package
+useless-import-alias:21:0::Import alias does not rename original package
+useless-import-alias:23:0::Import alias does not rename original package