Add Google Generative AI Conversation system prompt user_name and llm_context variables (#118510)

* Google Generative AI Conversation: Add variables to the system prompt

* User name and llm_context

* test for template variables

* test for template variables

---------

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

tests/components/google_generative_ai_conversation/test_conversation.py

@@ -449,6 +449,51 @@ async def test_template_error(
     assert result.response.error_code == "unknown", result
 
 
+async def test_template_variables(
+    hass: HomeAssistant, mock_config_entry: MockConfigEntry
+) -> None:
+    """Test that template variables work."""
+    context = Context(user_id="12345")
+    mock_user = MagicMock()
+    mock_user.id = "12345"
+    mock_user.name = "Test User"
+
+    hass.config_entries.async_update_entry(
+        mock_config_entry,
+        options={
+            "prompt": (
+                "The user name is {{ user_name }}. "
+                "The user id is {{ llm_context.context.user_id }}."
+            ),
+        },
+    )
+    with (
+        patch("google.generativeai.GenerativeModel") as mock_model,
+        patch("homeassistant.auth.AuthManager.async_get_user", return_value=mock_user),
+    ):
+        await hass.config_entries.async_setup(mock_config_entry.entry_id)
+        await hass.async_block_till_done()
+        mock_chat = AsyncMock()
+        mock_model.return_value.start_chat.return_value = mock_chat
+        chat_response = MagicMock()
+        mock_chat.send_message_async.return_value = chat_response
+        mock_part = MagicMock()
+        mock_part.text = "Model response"
+        chat_response.parts = [mock_part]
+        result = await conversation.async_converse(
+            hass, "hello", None, context, agent_id=mock_config_entry.entry_id
+        )
+
+    assert (
+        result.response.response_type == intent.IntentResponseType.ACTION_DONE
+    ), result
+    assert (
+        "The user name is Test User."
+        in mock_model.mock_calls[1][2]["history"][0]["parts"]
+    )
+    assert "The user id is 12345." in mock_model.mock_calls[1][2]["history"][0]["parts"]
+
+
 async def test_conversation_agent(
     hass: HomeAssistant,
     mock_config_entry: MockConfigEntry,