add readme test

Author: nschloe

test/test_readme.py

@@ -0,0 +1,14 @@
+import pathlib
+
+import exdown
+import pytest
+
+this_dir = pathlib.Path(__file__).resolve().parent
+
+
+@pytest.mark.parametrize(
+    "string,lineno",
+    exdown.extract(this_dir.parent / "README.md", syntax_filter="python"),
+)
+def test_readme(string, lineno):
+    exec(string)