Unit test for black-approved coding style

setup.py

@@ -22,7 +22,7 @@ setup(
     packages=find_packages(),
     install_requires=["click==6.7"],
     setup_requires=["pytest-runner"],
-    tests_require=["pytest==3.2.3"],
+    tests_require=["pytest==3.2.3", "black==18.6b4"],
     entry_points="""
         [console_scripts]
         sqlite-utils=sqlite_utils.cli:cli

tests/test_black.py

@@ -0,0 +1,14 @@
+import black
+from click.testing import CliRunner
+from pathlib import Path
+
+code_root = Path(__file__).parent.parent
+
+
+def test_black():
+    runner = CliRunner()
+    result = runner.invoke(
+        black.main,
+        [str(code_root / "tests"), str(code_root / "sqlite_utils"), "--check"],
+    )
+    assert result.exit_code == 0, result.output