style: Format test_sendchat.py with consistent newlines

tests/basic/test_sendchat.py

@@ -96,18 +96,21 @@ def test_simple_send_non_retryable_error(self, mock_print, mock_completion):
 
     def test_ensure_alternating_roles_empty(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = []
         result = ensure_alternating_roles(messages)
         assert result == []
 
     def test_ensure_alternating_roles_single_message(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = [{"role": "user", "content": "Hello"}]
         result = ensure_alternating_roles(messages)
         assert result == messages
 
     def test_ensure_alternating_roles_already_alternating(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = [
             {"role": "user", "content": "Hello"},
             {"role": "assistant", "content": "Hi there"},
@@ -118,6 +121,7 @@ def test_ensure_alternating_roles_already_alternating(self):
 
     def test_ensure_alternating_roles_consecutive_user(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = [
             {"role": "user", "content": "Hello"},
             {"role": "user", "content": "Are you there?"},
@@ -132,6 +136,7 @@ def test_ensure_alternating_roles_consecutive_user(self):
 
     def test_ensure_alternating_roles_consecutive_assistant(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = [
             {"role": "assistant", "content": "Hi there"},
             {"role": "assistant", "content": "How can I help?"},
@@ -146,6 +151,7 @@ def test_ensure_alternating_roles_consecutive_assistant(self):
 
     def test_ensure_alternating_roles_mixed_sequence(self):
         from aider.sendchat import ensure_alternating_roles
+
         messages = [
             {"role": "user", "content": "Hello"},
             {"role": "user", "content": "Are you there?"},