diff --git a/simplemind/__init__.py b/simplemind/__init__.py
index 53f6a7e..33d4229 100644
--- a/simplemind/__init__.py
+++ b/simplemind/__init__.py
@@ -64,16 +64,16 @@ def create_conversation(
     """Create a new conversation."""
 
     # Create the conversation.
-    conversation = Conversation(
+    conv = Conversation(
         llm_model=llm_model,
         llm_provider=llm_provider or settings.DEFAULT_LLM_PROVIDER,
     )
 
     # Add plugins to the conversation.
     for plugin in plugins or []:
-        conversation.add_plugin(plugin)
+        conv.add_plugin(plugin)
 
-    return conversation
+    return conv
 
 
 def generate_data(
diff --git a/simplemind/models.py b/simplemind/models.py
index 8a32fb9..e2e22ab 100644
--- a/simplemind/models.py
+++ b/simplemind/models.py
@@ -116,17 +116,23 @@ class Conversation(SMBaseModel):
                 except NotImplementedError:
                     pass
 
-    def prepend_system_message(
-        self, text: str, meta: Dict[str, Any] | None = None
-    ):
+    def prepend_system_message(self, text: str, meta: Dict[str, Any] | None = None):
         """Prepend a system message to the conversation."""
-        self.messages = [Message(role="system", text=text, meta=meta or {})] + self.messages
+        self.messages = [
+            Message(role="system", text=text, meta=meta or {})
+        ] + self.messages
 
     def add_message(
-        self, role: MESSAGE_ROLE, text: str, meta: Optional[Dict[str, Any]] = None
+        self,
+        role: MESSAGE_ROLE = "user",
+        text: str | None = None,
+        *,
+        meta: Optional[Dict[str, Any]] = None,
     ):
         """Add a new message to the conversation."""
 
+        assert text is not None
+
         # Ensure meta is a dict.
         if meta is None:
             meta = {}
@@ -151,6 +157,8 @@ class Conversation(SMBaseModel):
     ) -> Message:
         """Send the conversation to the LLM."""
 
+        # TODO: llm_model and llm_provider should override the conversation's.
+
         # Execute all pre send hooks.
         for plugin in self.plugins:
             if hasattr(plugin, "pre_send_hook"):
diff --git a/tests/test_conversations.py b/tests/test_conversations.py
new file mode 100644
index 0000000..b0c85dd
--- /dev/null
+++ b/tests/test_conversations.py
@@ -0,0 +1,28 @@
+import pytest
+
+from simplemind.providers import Anthropic, Gemini, OpenAI, Groq, Ollama, Amazon
+
+import simplemind as sm
+
+
+@pytest.mark.parametrize(
+    "provider_cls",
+    [
+        Anthropic,
+        Gemini,
+        OpenAI,
+        Groq,
+        Ollama,
+        # Amazon
+    ],
+)
+def test_generate_data(provider_cls):
+    conv = sm.create_conversation(
+        llm_model=provider_cls.DEFAULT_MODEL, llm_provider=provider_cls.NAME
+    )
+
+    conv.add_message(text="hey")
+    data = conv.send()
+
+    assert isinstance(data.text, str)
+    assert len(data.text) > 0
diff --git a/tests/test_generate_data.py b/tests/test_generate_data.py
index dc07300..610c96a 100644
--- a/tests/test_generate_data.py
+++ b/tests/test_generate_data.py
@@ -1,4 +1,3 @@
-
 import pytest
 
 from simplemind.providers import Anthropic, Gemini, OpenAI, Groq, Ollama, Amazon
@@ -18,7 +17,7 @@ class ResponseModel(BaseModel):
         OpenAI,
         Groq,
         Ollama,
-        Amazon
+        # Amazon
     ],
 )
 def test_generate_data(provider_cls):
diff --git a/tests/test_generate_text.py b/tests/test_generate_text.py
index 0611b1d..4ab62cf 100644
--- a/tests/test_generate_text.py
+++ b/tests/test_generate_text.py
@@ -11,7 +11,7 @@ from simplemind.providers import Anthropic, Gemini, OpenAI, Groq, Ollama, Amazon
         OpenAI,
         Groq,
         Ollama,
-        Amazon,
+        # Amazon,
     ],
 )
 def test_generate_text(provider_cls):