feat: adds test cases for loop component compatibility with the APIs, Loop component updates to support API

[edwinjosechittilappilly]

This pull request includes significant changes to the LoopComponent class and its associated tests. The most important changes include refactoring the initialize_data method, adding new methods for loop control, and updating the test configurations and fixtures.

Refactoring and new methods in LoopComponent:

• src/backend/base/langflow/components/logic/loop.py: Refactored initialize_data to use a new _validate_data method. Added evaluate_stop_loop, done_output, loop_variables, and aggregated_output methods to improve loop control and data handling. [1] [2] [3]

Test configuration and fixtures:

• src/backend/tests/conftest.py: Added a new fixture json_loop_test and included pytest.LOOP_TEST in the test configuration. Changed the blockbuster fixture to not auto-use. [1] [2] [3] [4]

New test cases for LoopComponent:

• src/backend/tests/unit/components/logic/test_loop.py: Added a new test class TestLoopComponentWithAPI with test cases for building and running flow loops using the API.

Additional method in CustomComponent:

• src/backend/base/langflow/custom/custom_component/custom_component.py: Added a start method to complement the existing stop method for better flow control.

[ogabrielluiz]

Could you take a look at the TestBatchRunComponent test and build these tests using the same structure?

[codspeed-hq]

CodSpeed Performance Report

Merging #5615 will degrade performances by 49.6%

_{Comparing fix-loop (df3cefd) with main (43d22fd)}

Summary

❌ 1 regressions
✅ 14 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	fix-loop	Change
❌	test_get_and_cache_all_types_dict	1.1 ms	2.1 ms	-49.6%