fix: Ensure password is overrideable

Removes the explicit naming of the password parameter for asyncpg, and
moves the setting of the password to the kwargs. Further adds tests to
ensure that the password argument is preserved.

databases/backends/postgres.py

@@ -43,6 +43,7 @@ def _get_dialect(self) -> Dialect:
 
     def _get_connection_kwargs(self) -> dict:
         url_options = self._database_url.options
+        password = self._database_url.password
 
         kwargs = {}
         min_size = url_options.get("min_size")
@@ -56,6 +57,9 @@ def _get_connection_kwargs(self) -> dict:
         if ssl is not None:
             kwargs["ssl"] = {"true": True, "false": False}[ssl.lower()]
 
+        if password is not None:
+            kwargs["password"] = password
+
         kwargs.update(self._options)
 
         return kwargs
@@ -67,7 +71,6 @@ async def connect(self) -> None:
             host=self._database_url.hostname,
             port=self._database_url.port,
             user=self._database_url.username,
-            password=self._database_url.password,
             database=self._database_url.database,
             **kwargs,
         )

tests/test_connection_options.py

@@ -43,6 +43,30 @@ def test_postgres_explicit_ssl():
     assert kwargs == {"ssl": True}
 
 
+def test_postgres_no_extra_options():
+    backend = PostgresBackend("postgres://localhost/database")
+    kwargs = backend._get_connection_kwargs()
+    assert kwargs == {}
+
+
+def test_postgres_password_in_kwargs():
+    backend = PostgresBackend("postgres://:password@localhost/database")
+    kwargs = backend._get_connection_kwargs()
+    assert kwargs == {"password": "password"}
+
+
+def test_postgres_password_as_callable():
+    def gen_password():
+        return "Foo"
+
+    backend = PostgresBackend(
+        "postgres://:password@localhost/database", password=gen_password
+    )
+    kwargs = backend._get_connection_kwargs()
+    assert kwargs == {"password": gen_password}
+    assert kwargs["password"]() == "Foo"
+
+
 def test_mysql_pool_size():
     backend = MySQLBackend("mysql://localhost/database?min_size=1&max_size=20")
     kwargs = backend._get_connection_kwargs()