Remove "Enter .help" message; Redirect error to stderr

Author: tanloong

Lib/sqlite3/__main__.py

@@ -58,10 +58,11 @@ def runsource(self, source, filename="<input>", symbol="single"):
                     print("Enter SQL code and press enter.")
                 case "quit":
                     sys.exit(0)
+                case "":
+                    pass
                 case _ as unknown:
-                    if unknown:
-                        print("Error: unknown command or invalid arguments:"
-                              f'  "{unknown}". Enter ".help" for help')
+                    self.write("Error: unknown command or invalid arguments:"
+                               f'  "{unknown}".\n')
         else:
             if not sqlite3.complete_statement(source):
                 return True

Lib/test/test_sqlite3/test_cli.py

@@ -124,15 +124,21 @@ def test_interact_empty_source(self):
         self.assertEqual(out.count(self.PS2), 0)
 
     def test_interact_dot_commands_unknown(self):
-        out, err = self.run_cli(commands=(".unknown_command", "."))
+        out, err = self.run_cli(commands=(".unknown_command"))
         self.assertIn(self.MEMORY_DB_MSG, err)
         self.assertEndsWith(out, self.PS1)
-        self.assertEqual(out.count(self.PS1), 3)
+        self.assertEqual(out.count(self.PS1), 2)
         self.assertEqual(out.count(self.PS2), 0)
+        self.assertIn("Error", err)
         # test "unknown_command" is pointed out in the error message
-        self.assertIn("unknown_command", out)
-        # test ignore empty dot command "." to mimic sqlite3 CLI
-        self.assertEqual(out.count('Error'), 1)
+        self.assertIn("unknown_command", err)
+
+    def test_interact_dot_commands_empty(self):
+        out, err = self.run_cli(commands=("."))
+        self.assertIn(self.MEMORY_DB_MSG, err)
+        self.assertEndsWith(out, self.PS1)
+        self.assertEqual(out.count(self.PS1), 2)
+        self.assertEqual(out.count(self.PS2), 0)
 
     def test_interact_dot_commands_with_whitespaces(self):
         out, err = self.run_cli(commands=(".version ", ". version"))