New codemod: remove-future-imports

integration_tests/test_remove_future_imports.py

@@ -0,0 +1,36 @@
+from textwrap import dedent
+
+from core_codemods.remove_future_imports import RemoveFutureImports
+from integration_tests.base_test import (
+    BaseIntegrationTest,
+    original_and_expected_from_code_path,
+)
+
+
+class TestRemoveFutureImports(BaseIntegrationTest):
+    codemod = RemoveFutureImports
+    code_path = "tests/samples/future_imports.py"
+
+    original_code, _ = original_and_expected_from_code_path(code_path, [])
+    expected_new_code = dedent(
+        """\
+    from __future__ import annotations
+
+    print("HEY")
+    """
+    )
+
+    expected_diff = """\
+--- 
++++ 
+@@ -1,4 +1,3 @@
+-from __future__ import absolute_import
+-from __future__ import *
++from __future__ import annotations
+ 
+ print("HEY")
+"""
+
+    num_changes = 2
+    expected_line_change = "1"
+    change_description = RemoveFutureImports.CHANGE_DESCRIPTION

src/codemodder/scripts/generate_docs.py

@@ -170,6 +170,10 @@ class DocMetadata:
         importance="Low",
         guidance_explained="A statement with an exception by itself has no effect. Raising the exception is most likely the intended effect and thus we deem it safe.",
     ),
+    "remove-future-imports": DocMetadata(
+        importance="Low",
+        guidance_explained="Removing future imports is safe and will not cause any issues.",
+    ),
 }
 
 

src/core_codemods/__init__.py

@@ -15,6 +15,7 @@
 from .lxml_safe_parsing import LxmlSafeParsing
 from .order_imports import OrderImports
 from .process_creation_sandbox import ProcessSandbox
+from .remove_future_imports import RemoveFutureImports
 from .remove_unnecessary_f_str import RemoveUnnecessaryFStr
 from .remove_unused_imports import RemoveUnusedImports
 from .requests_verify import RequestsVerify
@@ -57,6 +58,7 @@
         LxmlSafeParsing,
         OrderImports,
         ProcessSandbox,
+        RemoveFutureImports,
         RemoveUnnecessaryFStr,
         RemoveUnusedImports,
         RequestsVerify,

src/core_codemods/docs/pixee_python_remove-future-imports.md

@@ -0,0 +1,11 @@
+Many older codebases have `__future__` imports for forwards compatibility with features. As of this writing, all but one of those features is now stable in all currently supported versions of Python and so the imports are no longer needed. While such imports are harmless, they are also unnecessary and in most cases you probably just forgot to remove them. 
+
+This codemod removes all such `__future__` imports, preserving only those that are still necessary for forwards compatibility. 
+
+Our changes look like the following:
+```diff
+ import os
+-from __future__ import print_function
+
+ print("HELLO")
+```

src/core_codemods/remove_future_imports.py

@@ -0,0 +1,57 @@
+import libcst as cst
+
+from codemodder.codemods.api import BaseCodemod, ReviewGuidance
+
+
+DEPRECATED_NAMES = [
+    "print_function",
+    "unicode_literals",
+    "division",
+    "absolute_import",
+    "generators",
+    "nested_scopes",
+    "with_statement",
+    "generator_stop",
+]
+CURRENT_NAMES = [
+    "annotations",
+]
+
+
+class RemoveFutureImports(BaseCodemod):
+    NAME = "remove-future-imports"
+    SUMMARY = "Remove deprecated `__future__` imports"
+    REVIEW_GUIDANCE = ReviewGuidance.MERGE_WITHOUT_REVIEW
+    DESCRIPTION = "Remove deprecated `__future__` imports"
+    REFERENCES = [
+        {
+            "url": "https://docs.python.org/3/library/__future__.html",
+            "description": "",
+        },
+    ]
+
+    def leave_ImportFrom(
+        self, original_node: cst.ImportFrom, updated_node: cst.ImportFrom
+    ):
+        match original_node:
+            case cst.ImportFrom(module=cst.Name(value="__future__"), names=names):
+                match names:
+                    case cst.ImportStar():
+                        names = [
+                            cst.ImportAlias(name=cst.Name(value=name))
+                            for name in CURRENT_NAMES
+                        ]
+                        self.add_change(original_node, self.CHANGE_DESCRIPTION)
+                        return original_node.with_changes(names=names)
+
+                updated_names: list[cst.ImportAlias] = [
+                    name for name in names if name.name.value not in DEPRECATED_NAMES
+                ]
+                self.add_change(original_node, self.CHANGE_DESCRIPTION)
+                return (
+                    updated_node.with_changes(names=updated_names)
+                    if updated_names
+                    else cst.RemoveFromParent()
+                )
+
+        return updated_node

tests/codemods/test_remove_future_imports.py

@@ -0,0 +1,39 @@
+import pytest
+
+from core_codemods.remove_future_imports import RemoveFutureImports, DEPRECATED_NAMES
+from tests.codemods.base_codemod_test import BaseCodemodTest
+
+
+class TestRemoveFutureImports(BaseCodemodTest):
+    codemod = RemoveFutureImports
+
+    @pytest.mark.parametrize("name", DEPRECATED_NAMES)
+    def test_remove_future_imports(self, tmpdir, name):
+        original_code = f"""
+        import os
+        from __future__ import {name}
+        print("HEY")
+        """
+        expected_code = """
+        import os
+        print("HEY")
+        """
+        self.run_and_assert(tmpdir, original_code, expected_code)
+
+    def test_update_import_star(self, tmpdir):
+        original_code = """
+        from __future__ import *
+        """
+        expected_code = """
+        from __future__ import annotations
+        """
+        self.run_and_assert(tmpdir, original_code, expected_code)
+
+    def test_update_import_deprecated_and_annotations(self, tmpdir):
+        original_code = """
+        from __future__ import print_function, annotations
+        """
+        expected_code = """
+        from __future__ import annotations
+        """
+        self.run_and_assert(tmpdir, original_code, expected_code)

tests/samples/future_imports.py

@@ -0,0 +1,4 @@
+from __future__ import absolute_import
+from __future__ import *
+
+print("HEY")