Accept no param in connect()

More friendly towards ``connect(**parse_dsn())``, and what psycopg3 does.

Close #1250

3 files changed, 21 insertions, 8 deletions

diff --git a/NEWS b/NEWS
index 3bd03f3..bf58d8e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,12 @@
 Current release
 ---------------
 
+What's new in psycopg 2.8.7
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Accept empty params as `~psycopg2.connect()` (:ticket:`#1250).
+
+
 What's new in psycopg 2.8.6
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/lib/__init__.py b/lib/__init__.py
index 3cd4640..52c82bc 100644
--- a/lib/__init__.py
+++ b/lib/__init__.py
@@ -120,9 +120,6 @@ def connect(dsn=None, connection_factory=None, cursor_factory=None, **kwargs):
     if 'async_' in kwargs:
         kwasync['async_'] = kwargs.pop('async_')
 
-    if dsn is None and not kwargs:
-        raise TypeError('missing dsn and no parameters')
-
     dsn = _ext.make_dsn(dsn, **kwargs)
     conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
     if cursor_factory is not None:
diff --git a/tests/test_module.py b/tests/test_module.py
index 78f4e43..f37dccd 100755
--- a/tests/test_module.py
+++ b/tests/test_module.py
@@ -50,12 +50,22 @@ class ConnectTestCase(unittest.TestCase):
     def tearDown(self):
         psycopg2._connect = self._connect_orig
 
-    def test_there_has_to_be_something(self):
-        self.assertRaises(TypeError, psycopg2.connect)
-        self.assertRaises(TypeError, psycopg2.connect,
+    def test_there_might_be_nothing(self):
+        psycopg2.connect()
+        self.assertEqual(self.args[0], '')
+        self.assertEqual(self.args[1], None)
+        self.assertEqual(self.args[2], False)
+
+        psycopg2.connect(
             connection_factory=lambda dsn, async_=False: None)
-        self.assertRaises(TypeError, psycopg2.connect,
-            async_=True)
+        self.assertEqual(self.args[0], '')
+        self.assertNotEqual(self.args[1], None)
+        self.assertEqual(self.args[2], False)
+
+        psycopg2.connect(async_=True)
+        self.assertEqual(self.args[0], '')
+        self.assertEqual(self.args[1], None)
+        self.assertEqual(self.args[2], True)
 
     def test_no_keywords(self):
         psycopg2.connect('')