Skip files if no rules are enabled

To avoid unnecessary processing of files if no rules are enabled for a given file the config is now checked before processing a file and if no rules are enabled the file is skipped.

src/fixit/api.py

@@ -119,6 +119,8 @@ def fixit_file(
     """
     Lint a single file on disk, detecting and generating appropriate configuration.
 
+    If no rules are enabled for the file, the file will be skipped.
+
     Generates a merged :ref:`configuration` based on all applicable config files.
     Reads file from disk as raw bytes, and uses :func:`fixit_bytes` to lint and apply
     any fixes to the content. Writes content back to disk if changes are detected.
@@ -130,9 +132,13 @@ def fixit_file(
     path = path.resolve()
 
     try:
-        content: FileContent = path.read_bytes()
         config = generate_config(path, options=options)
 
+        if not config.enable:
+            return
+
+        content: FileContent = path.read_bytes()
+
         updated = yield from fixit_bytes(path, content, config=config, autofix=autofix)
         if updated and updated != content:
             LOG.info(f"{path}: writing changes to file")

src/fixit/tests/smoke.py

@@ -228,3 +228,51 @@ def foo():
                     sorted(errors[multi]),
                 )
                 self.assertEqual(expected, multi.read_text())
+
+    def test_lint_directory_with_no_rules_enabled(self) -> None:
+        content = dedent(
+            """\
+                import foo
+                import bar
+
+                def func():
+                    value = f"hello world"
+            """
+        )
+        with self.subTest("lint"):
+            with TemporaryDirectory() as td:
+                tdp = Path(td).resolve()
+                path = tdp / "file.py"
+
+                (tdp / "pyproject.toml").write_text(
+                    "[tool.fixit]\ndisable=['fixit.rules']\n"
+                )
+
+                path.write_text(content)
+                result = self.runner.invoke(
+                    main,
+                    ["lint", path.as_posix()],
+                    catch_exceptions=False,
+                )
+
+                self.assertEqual(result.output, "")
+                self.assertEqual(result.exit_code, 0)
+
+        with self.subTest("fix"):
+            with TemporaryDirectory() as td:
+                tdp = Path(td).resolve()
+                path = tdp / "file.py"
+
+                (tdp / "pyproject.toml").write_text(
+                    "[tool.fixit]\ndisable=['fixit.rules']\n"
+                )
+
+                path.write_text(content)
+                result = self.runner.invoke(
+                    main,
+                    ["fix", "--automatic", path.as_posix()],
+                    catch_exceptions=False,
+                )
+
+                self.assertEqual(result.output, "")
+                self.assertEqual(result.exit_code, 0)