fix: Make from_template_and_variables async for backwards compatibility, add sync version, add tests and small fixes (#4500)

* Refactor `trace_name` property to use `_id` instead of `_vertex.id` for component identification

* Handle missing session_id attribute in component and agent classes

* Add SUPPORTED_VERSIONS constant for version tracking in tests

* Add utility to download components from GitHub in integration tests

* Rename TestComponent to ComponentForTesting to avoid conflict with pytest

* test: enhance PromptComponent tests for version support

Add parameterized testing for supported versions and a validation for the latest PromptComponent. This improves test coverage and ensures compatibility across different versions.

* refactor: move build_component_instance_for_tests utility to integration utils

* Make `from_template_and_variables` async for backwards compatibility and add sync version

* Refactor `PromptComponent` to use `Message.from_template` method across starter projects JSON files.

* add await to `from_template_and_variables` call

* Add async test for message prompt serialization and update cache directory handling

- Introduced `async` in `test_message_prompt_serialization` for asynchronous message creation.
- Added `test_message_sync_prompt_serialization` for synchronous message testing.
- Updated cache directory paths to "langflow_test" for test isolation.
- Utilized `monkeypatch` to set environment variable for cache directory in `langflow_cache_dir` fixture.

* Add fixture and existence check in test_schema_message.py

- Use `langflow_cache_dir` fixture in `test_message_with_single_image`.
- Add assertion to verify the existence of `second_image`.

* Add base test class to ensure file names are defined for all supported versions

* Remove default value for 'file_name' parameter in 'build_component_instance_for_tests' function

* Enhance `TestPromptComponent` with version-specific file name handling and base class integration

* Refactor test_prompt_component_versions to use FILE_NAMES_MAPPING directly

* Add component version tests and base classes for testing with/without client

* Simplify `build_component_instance_for_tests` by returning `cc_class` directly

* Refactor `TestPromptComponent` to use `ComponentTestBaseWithClient` and remove version tests

* Add assertion for LANGFLOW_CONFIG_DIR in test_message_with_multiple_images

* Refactor: update method call to `from_template` in `langchain_hub.py`

* Handle missing '_id' attribute in 'trace_name' method of custom_component.py

* Optimize `get_and_cache_all_types_dict` call by removing unnecessary thread usage in test.

src/backend/tests/base.py

@@ -0,0 +1,39 @@
+from typing import Any
+
+import pytest
+
+from tests.constants import SUPPORTED_VERSIONS
+from tests.integration.utils import build_component_instance_for_tests
+
+# Sentinel value to mark undefined test cases
+DID_NOT_EXIST = object()
+
+
+class ComponentTestBase:
+    component_class = None
+    DEFAULT_KWARGS: dict[str, Any] = {}
+    FILE_NAMES_MAPPING: dict[str, object | str] = {}
+
+    def test_all_versions_have_a_file_name_defined(self):
+        for version in SUPPORTED_VERSIONS:
+            assert version in self.FILE_NAMES_MAPPING
+            assert self.FILE_NAMES_MAPPING[version] is not None
+
+    def test_component_versions(self):
+        """Test if the component works across different versions."""
+        for version, file_name in self.FILE_NAMES_MAPPING.items():
+            if file_name is DID_NOT_EXIST:
+                continue
+
+            instance = build_component_instance_for_tests(version, file_name=file_name, **self.DEFAULT_KWARGS)
+            result = instance()
+            assert result is not None, f"{self.component_class.__name__} failed to execute in version {version}"
+
+
+@pytest.mark.usefixtures("client")
+class ComponentTestBaseWithClient:
+    pass
+
+
+class ComponentTestBaseWithoutClient:
+    pass

src/backend/tests/constants.py

@@ -0,0 +1 @@
+SUPPORTED_VERSIONS = ["1.0.15", "1.0.16", "1.0.17", "1.0.18", "1.0.19"]

src/backend/tests/integration/utils.py

@@ -7,6 +7,7 @@ import requests
 from astrapy.admin import parse_api_endpoint
 from langflow.api.v1.schemas import InputValueRequest
 from langflow.custom import Component
+from langflow.custom.eval import eval_custom_component_code
 from langflow.field_typing import Embeddings
 from langflow.graph import Graph
 from langflow.processing.process import run_graph_internal
@@ -105,6 +106,16 @@ def download_flow_from_github(name: str, version: str) -> JSONFlow:
     return JSONFlow(json=as_json)
 
 
+def download_component_from_github(module: str, file_name: str, version: str) -> Component:
+    version_string = f"v{version}" if version != "main" else version
+    response = requests.get(
+        f"https://raw.githubusercontent.com/langflow-ai/langflow/{version_string}/src/backend/base/langflow/components/{module}/{file_name}.py",
+        timeout=10,
+    )
+    response.raise_for_status()
+    return Component(_code=response.text)
+
+
 async def run_json_flow(
     json_flow: JSONFlow, run_input: Any | None = None, session_id: str | None = None
 ) -> dict[str, Any]:
@@ -170,3 +181,9 @@ async def run_single_component(
         graph, flow_id, session_id=session_id, inputs=graph_run_inputs, outputs=[component_id]
     )
     return graph.get_vertex(component_id).built_object
+
+
+def build_component_instance_for_tests(version: str, file_name: str, **kwargs):
+    component = download_component_from_github("prompts", file_name, version)
+    cc_class = eval_custom_component_code(component._code)
+    return cc_class(**kwargs)

src/backend/tests/unit/components/prompts/test_prompt_component.py

@@ -1,12 +1,30 @@
+import pytest
 from langflow.components.prompts import PromptComponent
 
+from tests.base import ComponentTestBaseWithClient
+
+
+@pytest.mark.usefixtures("client")
+class TestPromptComponent(ComponentTestBaseWithClient):
+    component_class = PromptComponent
+    DEFAULT_KWARGS = {"template": "Hello {name}!", "name": "John", "_session_id": "123"}
+    FILE_NAMES_MAPPING = {
+        "1.0.15": "Prompt",
+        "1.0.16": "Prompt",
+        "1.0.17": "Prompt",
+        "1.0.18": "Prompt",
+        "1.0.19": "Prompt",
+    }
 
-class TestPromptComponent:
     def test_post_code_processing(self):
-        component = PromptComponent(template="Hello {name}!", name="John")
+        component = self.component_class(**self.DEFAULT_KWARGS)
         frontend_node = component.to_frontend_node()
         node_data = frontend_node["data"]["node"]
         assert node_data["template"]["template"]["value"] == "Hello {name}!"
         assert "name" in node_data["custom_fields"]["template"]
         assert "name" in node_data["template"]
         assert node_data["template"]["name"]["value"] == "John"
+
+    def test_prompt_component_latest(self):
+        result = PromptComponent(**self.DEFAULT_KWARGS)()
+        assert result is not None

src/backend/tests/unit/custom/custom_component/test_component_events.py

@@ -17,7 +17,7 @@ async def create_event_queue():
     return asyncio.Queue()
 
 
-class TestComponent(Component):
+class ComponentForTesting(Component):
     """Test component that implements basic functionality."""
 
     def build(self) -> None:
@@ -40,7 +40,7 @@ async def test_component_message_sending():
     event_manager = EventManager(queue)
 
     # Create component
-    component = TestComponent()
+    component = ComponentForTesting()
     component.set_event_manager(event_manager)
 
     # Create a message
@@ -68,7 +68,7 @@ async def test_component_tool_output():
     event_manager = EventManager(queue)
 
     # Create component
-    component = TestComponent()
+    component = ComponentForTesting()
     component.set_event_manager(event_manager)
 
     # Create a message with tool content
@@ -101,7 +101,7 @@ async def test_component_error_handling():
     event_manager = EventManager(queue)
 
     # Create component
-    component = TestComponent()
+    component = ComponentForTesting()
     component.set_event_manager(event_manager)
 
     # Trigger an error
@@ -133,7 +133,7 @@ async def test_component_build_results():
     event_manager = EventManager(queue)
 
     # Create component
-    component = TestComponent()
+    component = ComponentForTesting()
     component.set_event_manager(event_manager)
 
     # Add outputs to the component
@@ -165,7 +165,7 @@ async def test_component_logging():
     event_manager = EventManager(queue)
 
     # Create component
-    component = TestComponent()
+    component = ComponentForTesting()
     component.set_event_manager(event_manager)
 
     # Set current output (required for logging)
@@ -205,7 +205,7 @@ async def test_component_streaming_message():
     mock_graph.flow_id = "12345678-1234-5678-1234-567812345678"  # Valid UUID string
     vertex.graph = mock_graph
 
-    component = TestComponent(_vertex=vertex)
+    component = ComponentForTesting(_vertex=vertex)
     component.set_event_manager(event_manager)
 
     # Create a chunk class that mimics LangChain's streaming format

src/backend/tests/unit/schema/test_schema_message.py

@@ -49,7 +49,7 @@ def sample_image(langflow_cache_dir):
 
 def test_message_prompt_serialization():
     template = "Hello, {name}!"
-    message = Message.from_template_and_variables(template, name="Langflow")
+    message = Message.from_template(template, name="Langflow")
     assert message.text == "Hello, Langflow!"
 
     prompt = message.load_lc_prompt()