From eb6913c1d6adbc1943effd3e635ce0ce42583732 Mon Sep 17 00:00:00 2001
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Sat, 23 May 2020 13:29:15 +1200
Subject: [PATCH] Acept string subtypes as connection string

---
 psycopg3/conninfo.py           | 5 +++--
 tests/test_async_connection.py | 8 ++++++++
 tests/test_connection.py       | 8 ++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/psycopg3/conninfo.py b/psycopg3/conninfo.py
index 0fdce34c4..f5f07f361 100644
--- a/psycopg3/conninfo.py
+++ b/psycopg3/conninfo.py
@@ -14,10 +14,11 @@ def make_conninfo(conninfo: str = "", **kwargs: Any) -> str:
     if not conninfo and not kwargs:
         return ""
 
-    # If no kwarg is specified don't mung the conninfo but check if it's correct
+    # If no kwarg specified don't mung the conninfo but check if it's correct.
+    # Make sure to return a string, not a subtypep, to avoid making Liskov sad.
     if not kwargs:
         _parse_conninfo(conninfo)
-        return conninfo
+        return str(conninfo)
 
     # Override the conninfo with the parameters
     # Drop the None arguments
diff --git a/tests/test_async_connection.py b/tests/test_async_connection.py
index fa84c2bdd..4ea0ee068 100644
--- a/tests/test_async_connection.py
+++ b/tests/test_async_connection.py
@@ -24,6 +24,14 @@ async def test_connect_bad():
         await AsyncConnection.connect("dbname=nosuchdb")
 
 
+async def test_connect_str_subclass(dsn):
+    class MyString(str):
+        pass
+
+    conn = await AsyncConnection.connect(MyString(dsn))
+    assert conn.status == conn.ConnStatus.OK
+
+
 async def test_close(aconn):
     assert not aconn.closed
     await aconn.close()
diff --git a/tests/test_connection.py b/tests/test_connection.py
index 794295b55..0a83d2f9a 100644
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -16,6 +16,14 @@ def test_connect(dsn):
     assert conn.status == conn.ConnStatus.OK
 
 
+def test_connect_str_subclass(dsn):
+    class MyString(str):
+        pass
+
+    conn = Connection.connect(MyString(dsn))
+    assert conn.status == conn.ConnStatus.OK
+
+
 def test_connect_bad():
     with pytest.raises(psycopg3.OperationalError):
         Connection.connect("dbname=nosuchdb")
-- 
2.47.3