[primer] Create a class for easier comparison of pylint results

pylint/testutils/_primer/comparator.py

@@ -0,0 +1,41 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
+# Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
+
+from __future__ import annotations
+
+import json
+from collections.abc import Generator
+from pathlib import Path
+
+from pylint.testutils._primer.primer_command import Messages, PackageMessages
+
+
+class Comparator:
+    def __init__(self, main_json: Path, pr_json: Path):
+        main_messages = self._load_json(main_json)
+        self.pr_messages = self._load_json(pr_json)
+        self.missing_messages: PackageMessages = {}
+        for package, messages in main_messages.items():
+            self.missing_messages[package] = []
+            for message in messages:
+                try:
+                    self.pr_messages[package].remove(message)
+                except ValueError:
+                    self.missing_messages[package].append(message)
+
+    def __iter__(
+        self,
+    ) -> Generator[tuple[str, Messages, Messages], None, None]:
+        for package, missing_messages in self.missing_messages.items():
+            new_messages = self.pr_messages[package]
+            if not missing_messages and not new_messages:
+                print(f"PRIMER: No changes in {package}.")
+                continue
+            yield package, missing_messages, new_messages
+
+    @staticmethod
+    def _load_json(file_path: Path | str) -> PackageMessages:
+        with open(file_path, encoding="utf-8") as f:
+            result: PackageMessages = json.load(f)
+        return result

pylint/testutils/_primer/primer_command.py

@@ -11,7 +11,8 @@
 
 from pylint.testutils._primer import PackageToLint
 
-PackageMessages = Dict[str, List[Dict[str, Union[str, int]]]]
+Messages = List[Dict[str, Union[str, int]]]
+PackageMessages = Dict[str, Messages]
 
 
 class PrimerCommand:

pylint/testutils/_primer/primer_compare_command.py

@@ -3,55 +3,24 @@
 # Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
 from __future__ import annotations
 
-import json
-from pathlib import Path
-
-from pylint.testutils._primer.primer_command import PackageMessages, PrimerCommand
+from pylint.testutils._primer.comparator import Comparator
+from pylint.testutils._primer.primer_command import Messages, PrimerCommand
 
 MAX_GITHUB_COMMENT_LENGTH = 65536
 
 
 class CompareCommand(PrimerCommand):
     def run(self) -> None:
-        main_messages = self._load_json(self.config.base_file)
-        pr_messages = self._load_json(self.config.new_file)
-        missing_messages, new_messages = self._cross_reference(
-            main_messages, pr_messages
-        )
-        comment = self._create_comment(missing_messages, new_messages)
+        comparator = Comparator(self.config.base_file, self.config.new_file)
+        comment = self._create_comment(comparator)
         with open(self.primer_directory / "comment.txt", "w", encoding="utf-8") as f:
             f.write(comment)
 
-    @staticmethod
-    def _cross_reference(
-        main_dict: PackageMessages, pr_messages: PackageMessages
-    ) -> tuple[PackageMessages, PackageMessages]:
-        missing_messages: PackageMessages = {}
-        for package, messages in main_dict.items():
-            missing_messages[package] = []
-            for message in messages:
-                try:
-                    pr_messages[package].remove(message)
-                except ValueError:
-                    missing_messages[package].append(message)
-        return missing_messages, pr_messages
-
-    @staticmethod
-    def _load_json(file_path: Path | str) -> PackageMessages:
-        with open(file_path, encoding="utf-8") as f:
-            result: PackageMessages = json.load(f)
-        return result
-
-    def _create_comment(
-        self, all_missing_messages: PackageMessages, all_new_messages: PackageMessages
-    ) -> str:
+    def _create_comment(self, comparator: Comparator) -> str:
         comment = ""
-        for package, missing_messages in all_missing_messages.items():
+        for package, missing_messages, new_messages in comparator:
             if len(comment) >= MAX_GITHUB_COMMENT_LENGTH:
                 break
-            new_messages = all_new_messages[package]
-            if not missing_messages and not new_messages:
-                continue
             comment += self._create_comment_for_package(
                 package, new_messages, missing_messages
             )
@@ -67,7 +36,7 @@ def _create_comment(
         return self._truncate_comment(comment)
 
     def _create_comment_for_package(
-        self, package: str, new_messages, missing_messages
+        self, package: str, new_messages: Messages, missing_messages: Messages
     ) -> str:
         comment = f"\n\n**Effect on [{package}]({self.packages[package].url}):**\n"
         # Create comment for new messages