add code and unit test for detecting missing pydantic dependency and …

…output to stdout

bump_pydantic/codemods/replace_imports.py

@@ -13,10 +13,12 @@
 from dataclasses import dataclass
 from typing import Sequence
 
+import sys
 import libcst as cst
 import libcst.matchers as m
 from libcst.codemod import CodemodContext, VisitorBasedCodemodCommand
 from libcst.codemod.visitors import AddImportsVisitor
+from importlib.util import find_spec
 
 IMPORTS = {
     "pydantic:BaseSettings": ("pydantic_settings", "BaseSettings"),
@@ -35,6 +37,13 @@
 }
 
 
+def find_package_install(package_name: str) -> bool:
+    try:
+        return find_spec(package_name) is not None
+    except ModuleNotFoundError:
+        return False
+
+
 def resolve_module_parts(module_parts: list[str]) -> m.Attribute | m.Name:
     if len(module_parts) == 1:
         return m.Name(module_parts[0])
@@ -98,11 +107,20 @@ class ImportInfo:
 class ReplaceImportsCodemod(VisitorBasedCodemodCommand):
     @m.leave(IMPORT_MATCH)
     def leave_replace_import(self, _: cst.ImportFrom, updated_node: cst.ImportFrom) -> cst.ImportFrom:
+        to_do_warnings = set()
         for import_info in IMPORT_INFOS:
             if m.matches(updated_node, import_info.import_from):
                 aliases: Sequence[cst.ImportAlias] = updated_node.names  # type: ignore
                 # If multiple objects are imported in a single import statement,
                 # we need to remove only the one we're replacing.
+                package_not_installed = not find_package_install(import_info.to_import_str[0])
+                if package_not_installed:
+                    import_info_part = import_info.to_import_str[0].split('.')[0]
+                    to_do_warning = f" #todo: please install {import_info_part}\n"
+                    if to_do_warning not in to_do_warnings:
+                        sys.stdout.write(to_do_warning)
+                        sys.stdout.flush()
+                        to_do_warnings.add(to_do_warning)
                 AddImportsVisitor.add_needed_import(self.context, *import_info.to_import_str)
                 if len(updated_node.names) > 1:  # type: ignore
                     names = [alias for alias in aliases if alias.name.value != import_info.to_import_str[-1]]

tests/unit/test_replace_imports.py

@@ -1,12 +1,31 @@
 import pytest
+import sys
+import io
+import importlib
 from libcst.codemod import CodemodTest
-
+from contextlib import contextmanager
 from bump_pydantic.codemods.replace_imports import ReplaceImportsCodemod
 
 
+def is_package_installed(package_name):
+    try:
+        importlib.import_module(package_name)
+        return True
+    except ImportError:
+        return False
+
+
 class TestReplaceImportsCommand(CodemodTest):
     TRANSFORM = ReplaceImportsCodemod
 
+    @contextmanager
+    def capture_stdout(self):
+        new_stdout = io.StringIO()
+        old_stdout = sys.stdout
+        sys.stdout = new_stdout
+        yield new_stdout
+        sys.stdout = old_stdout
+
     def test_base_settings(self) -> None:
         before = """
         from pydantic import BaseSettings
@@ -16,11 +35,22 @@ def test_base_settings(self) -> None:
         """
         self.assertCodemod(before, after)
 
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_settings"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_settings"
+            assert captured.getvalue().strip() == expected_stdout
+
     def test_noop_base_settings(self) -> None:
         code = """
         from potato import BaseSettings
         """
-        self.assertCodemod(code, code)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(code, code)
+        assert captured.getvalue().strip() == "", "stdout is not empty as expected."
 
     @pytest.mark.xfail(reason="To be implemented.")
     def test_base_settings_as(self) -> None:
@@ -39,7 +69,15 @@ def test_color(self) -> None:
         after = """
         from pydantic_extra_types.color import Color
         """
-        self.assertCodemod(before, after)
+
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_extra_types"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_extra_types"
+            assert captured.getvalue().strip() == expected_stdout
 
     def test_color_full(self) -> None:
         before = """
@@ -48,13 +86,23 @@ def test_color_full(self) -> None:
         after = """
         from pydantic_extra_types.color import Color
         """
-        self.assertCodemod(before, after)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_extra_types"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_extra_types"
+            assert captured.getvalue().strip() == expected_stdout
 
     def test_noop_color(self) -> None:
         code = """
         from potato import Color
         """
         self.assertCodemod(code, code)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(code, code)
+        assert captured.getvalue().strip() == "", "stdout is not empty as expected."
 
     def test_payment_card_number(self) -> None:
         before = """
@@ -63,7 +111,14 @@ def test_payment_card_number(self) -> None:
         after = """
         from pydantic_extra_types.payment import PaymentCardNumber
         """
-        self.assertCodemod(before, after)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_extra_types"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_extra_types"
+            assert captured.getvalue().strip() == expected_stdout
 
     def test_payment_card_brand(self) -> None:
         before = """
@@ -72,19 +127,30 @@ def test_payment_card_brand(self) -> None:
         after = """
         from pydantic_extra_types.payment import PaymentCardBrand
         """
-        self.assertCodemod(before, after)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_extra_types"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_extra_types"
+            assert captured.getvalue().strip() == expected_stdout
 
     def test_noop_payment_card_number(self) -> None:
         code = """
         from potato import PaymentCardNumber
         """
-        self.assertCodemod(code, code)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(code, code)
+        assert captured.getvalue().strip() == "", "stdout is not empty as expected."
 
     def test_noop_payment_card_brand(self) -> None:
         code = """
         from potato import PaymentCardBrand
         """
-        self.assertCodemod(code, code)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(code, code)
+        assert captured.getvalue().strip() == "", "stdout is not empty as expected."
 
     def test_both_payment(self) -> None:
         before = """
@@ -93,4 +159,11 @@ def test_both_payment(self) -> None:
         after = """
         from pydantic_extra_types.payment import PaymentCardBrand, PaymentCardNumber
         """
-        self.assertCodemod(before, after)
+        with self.capture_stdout() as captured:
+            self.assertCodemod(before, after)
+
+        if is_package_installed("pydantic_extra_types"):
+            assert captured.getvalue().strip() == "", "stdout is not empty as expected."
+        else:
+            expected_stdout = "#todo: please install pydantic_extra_types"
+            assert captured.getvalue().strip() == expected_stdout