feat: add a unified language model component. (#6994)

* add a unified language model component with a few providers

* [autofix.ci] apply automated fixes

* fix errors and add tests

* [autofix.ci] apply automated fixes

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Edwin Jose <edwin.jose@datastax.com>

src/backend/tests/unit/components/models/test_language_model_component.py

@@ -0,0 +1,128 @@
+from unittest.mock import MagicMock, patch
+
+import pytest
+from langflow.base.models.anthropic_constants import ANTHROPIC_MODELS
+from langflow.base.models.openai_constants import OPENAI_MODEL_NAMES
+from langflow.components.models import LanguageModelComponent
+
+from tests.base import ComponentTestBaseWithClient
+
+
+@pytest.mark.usefixtures("client")
+class TestLanguageModelComponent(ComponentTestBaseWithClient):
+    @pytest.fixture
+    def component_class(self):
+        return LanguageModelComponent
+
+    @pytest.fixture
+    def default_kwargs(self):
+        return {
+            "provider": "OpenAI",
+            "model_name": "gpt-3.5-turbo",
+            "api_key": "test-api-key",
+            "temperature": 0.1,
+            "system_message": "You are a helpful assistant.",
+            "input_value": "Hello, how are you?",
+            "stream": False,
+        }
+
+    @pytest.fixture
+    def file_names_mapping(self):
+        """Return the file names mapping for version-specific files."""
+
+    async def test_update_build_config_openai(self, component_class, default_kwargs):
+        component = component_class(**default_kwargs)
+        build_config = {
+            "model_name": {"options": [], "value": ""},
+            "api_key": {"display_name": "API Key"},
+        }
+        updated_config = component.update_build_config(build_config, "OpenAI", "provider")
+        assert updated_config["model_name"]["options"] == OPENAI_MODEL_NAMES
+        assert updated_config["model_name"]["value"] == OPENAI_MODEL_NAMES[0]
+        assert updated_config["api_key"]["display_name"] == "OpenAI API Key"
+
+    async def test_update_build_config_anthropic(self, component_class, default_kwargs):
+        component = component_class(**default_kwargs)
+        build_config = {
+            "model_name": {"options": [], "value": ""},
+            "api_key": {"display_name": "API Key"},
+        }
+        updated_config = component.update_build_config(build_config, "Anthropic", "provider")
+        assert updated_config["model_name"]["options"] == ANTHROPIC_MODELS
+        assert updated_config["model_name"]["value"] == ANTHROPIC_MODELS[0]
+        assert updated_config["api_key"]["display_name"] == "Anthropic API Key"
+
+    @patch("langflow.components.models.language_model.ChatOpenAI")
+    async def test_build_model_openai(self, mock_chat_openai, component_class, default_kwargs):
+        # Setup mock
+        mock_instance = MagicMock()
+        mock_chat_openai.return_value = mock_instance
+
+        # Create and configure the component
+        component = component_class(**default_kwargs)
+        component.provider = "OpenAI"
+        component.model_name = "gpt-3.5-turbo"
+        component.api_key = "test-key"
+        component.temperature = 0.5
+        component.stream = False
+
+        # Build the model
+        model = component.build_model()
+
+        # Verify the ChatOpenAI was called with the correct parameters
+        mock_chat_openai.assert_called_once_with(
+            model_name="gpt-3.5-turbo",
+            temperature=0.5,
+            streaming=False,
+            openai_api_key="test-key",
+        )
+        assert model == mock_instance
+
+    @patch("langflow.components.models.language_model.ChatAnthropic")
+    async def test_build_model_anthropic(self, mock_chat_anthropic, component_class, default_kwargs):
+        # Setup mock
+        mock_instance = MagicMock()
+        mock_chat_anthropic.return_value = mock_instance
+
+        # Create and configure the component
+        component = component_class(**default_kwargs)
+        component.provider = "Anthropic"
+        component.model_name = ANTHROPIC_MODELS[0]  # Use the first model from the constants
+        component.api_key = "test-key"
+        component.temperature = 0.7
+        component.stream = False
+
+        # Build the model
+        model = component.build_model()
+
+        # Verify the ChatAnthropic was called with the correct parameters
+        mock_chat_anthropic.assert_called_once_with(
+            model=ANTHROPIC_MODELS[0],
+            temperature=0.7,
+            streaming=False,
+            anthropic_api_key="test-key",
+        )
+        assert model == mock_instance
+
+    async def test_build_model_openai_missing_api_key(self, component_class, default_kwargs):
+        component = component_class(**default_kwargs)
+        component.provider = "OpenAI"
+        component.api_key = None
+
+        with pytest.raises(ValueError, match="OpenAI API key is required when using OpenAI provider"):
+            component.build_model()
+
+    async def test_build_model_anthropic_missing_api_key(self, component_class, default_kwargs):
+        component = component_class(**default_kwargs)
+        component.provider = "Anthropic"
+        component.api_key = None
+
+        with pytest.raises(ValueError, match="Anthropic API key is required when using Anthropic provider"):
+            component.build_model()
+
+    async def test_build_model_unknown_provider(self, component_class, default_kwargs):
+        component = component_class(**default_kwargs)
+        component.provider = "Unknown"
+
+        with pytest.raises(ValueError, match="Unknown provider: Unknown"):
+            component.build_model()