Add a test illustrating python and postgres encoding mismatch

See #348 (comment)

tests/test_data.py

@@ -139,6 +139,24 @@ def test_encoding(postgresql, data, execute):
     assert blocking.query and "blocking éléphant" in blocking.query
 
 
+@pytest.mark.parametrize(
+    "pyenc, pgenc",
+    [
+        ("utf8", "UTF8"),
+        pytest.param("ascii", "SQL_ASCII", marks=pytest.mark.xfail),
+    ],
+)
+def test_postgres_and_python_encoding(pyenc: str, pgenc: str, data, postgresql) -> None:
+    dbname = pyenc
+    with psycopg.connect(postgresql.info.dsn, autocommit=True) as conn:
+        conn.execute(f"CREATE DATABASE {dbname} ENCODING {pgenc} TEMPLATE template0")
+    with psycopg.connect(postgresql.info.dsn, dbname=dbname) as conn:
+        conn.execute("SELECT 'encoding'")
+        (running,) = data.pg_get_activities()
+    assert "'encoding'" in running.query
+    assert running.encoding.lower() == pyenc
+
+
 def test_filters_dbname(data, execute):
     data_filtered = attr.evolve(data, filters=types.Filters(dbname="temp"))
     execute("SELECT pg_sleep(2)", dbname="template1", autocommit=True)