Return non-zero exit codes for violations/errors

This tracks exit codes based on the existence of violations and/or
errors when linting files.

- 0: everything clean
- 1: violations only
- 2: errors only
- 3: both violations and errors

Fixes #258

[ghstack-poisoned]

src/fixit/api.py

@@ -36,9 +36,9 @@ def print_result(result: Result, debug: bool = False) -> None:
         # An exception occurred while processing a file
         error, tb = result.error
         if debug:
-            click.secho(f"{error}: {tb}", fg="red")
+            click.secho(f"{path}: {error}: {tb}", fg="red")
         else:
-            click.secho(f"{error}", fg="red")
+            click.secho(f"{path}: {error}", fg="red")
 
 
 def _make_result(path: Path, violations: Iterable[LintViolation]) -> Iterable[Result]:

src/fixit/tests/smoke.py

@@ -4,6 +4,7 @@
 # LICENSE file in the root directory of this source tree.
 
 from pathlib import Path
+from tempfile import TemporaryDirectory
 from unittest import TestCase
 
 from click.testing import CliRunner
@@ -30,3 +31,35 @@ def test_this_project_is_clean(self) -> None:
         result = self.runner.invoke(main, ["lint", project_dir], catch_exceptions=False)
         self.assertEqual(result.output, "")
         self.assertEqual(result.exit_code, 0)
+
+    def test_directory_with_violations(self) -> None:
+        with TemporaryDirectory() as td:
+            tdp = Path(td).resolve()
+            (tdp / "clean.py").write_text("name = 'Kirby'\nprint(f'hello {name}')")
+            (tdp / "dirty.py").write_text("name = 'Kirby'\nprint('hello %s' % name)\n")
+
+            result = self.runner.invoke(main, ["lint", td])
+            self.assertIn("dirty.py@2:6 UseFstringRule:", result.output)
+            self.assertEqual(result.exit_code, 1)
+
+    def test_directory_with_errors(self) -> None:
+        with TemporaryDirectory() as td:
+            tdp = Path(td).resolve()
+            (tdp / "clean.py").write_text("name = 'Kirby'\nprint(f'hello {name}')")
+            (tdp / "broken.py").write_text("print)\n")
+
+            result = self.runner.invoke(main, ["lint", td])
+            self.assertIn("broken.py: Syntax Error @ 1:6.", result.output)
+            self.assertEqual(result.exit_code, 2)
+
+    def test_directory_with_violations_and_errors(self) -> None:
+        with TemporaryDirectory() as td:
+            tdp = Path(td).resolve()
+            (tdp / "clean.py").write_text("name = 'Kirby'\nprint(f'hello {name}')")
+            (tdp / "dirty.py").write_text("name = 'Kirby'\nprint('hello %s' % name)\n")
+            (tdp / "broken.py").write_text("print)\n")
+
+            result = self.runner.invoke(main, ["lint", td])
+            self.assertIn("dirty.py@2:6 UseFstringRule:", result.output)
+            self.assertIn("broken.py: Syntax Error @ 1:6.", result.output)
+            self.assertEqual(result.exit_code, 3)