Sort commits using isort

Also added lint test to ensure they stay sorted.

tests/test_lint.py

@@ -0,0 +1,38 @@
+import io
+import sys
+from pathlib import Path
+
+import isort
+import pytest
+from click.testing import CliRunner
+
+code_root = Path(__file__).parent.parent
+
+
+@pytest.mark.skipif(
+    sys.version_info[:2] < (3, 6), reason="Black requires Python 3.6 or later"
+)
+def test_black():
+    # Do not import at top of module because Python 3.5 will not have it installed
+    import black
+
+    runner = CliRunner()
+    result = runner.invoke(
+        black.main, [str(code_root / "tests"), str(code_root / "datasette"), "--check"]
+    )
+    assert result.exit_code == 0, result.output
+
+
+@pytest.mark.parametrize(
+    "path",
+    list(code_root.glob("tests/**/*.py")) + list(code_root.glob("datasette/**/*.py")),
+)
+def test_isort(path):
+    # Have to capture stdout because isort uses print() directly
+    stdout = sys.stdout
+    sys.stdout = io.StringIO()
+    result = isort.SortImports(path, check=True)
+    assert (
+        not result.incorrectly_sorted
+    ), "{} has incorrectly sorted imports, fix with 'isort -rc tests && isort -rc datasette && black tests datasette'"
+    sys.stdout = stdout