refactor: move tests folder structure and update pytest commands (#2785)

* refactor: move tests folder to src/backend

* chore(Makefile): update pytest commands to run tests from the correct directory paths for unit and integration tests

* refactor: update file path in test_custom_component.py

The file path in the test_custom_component.py file has been updated to use the correct relative path to the component_multiple_outputs.py file. This change ensures that the test code can access the correct file and improves the reliability of the test.

src/backend/tests/unit/test_template.py

@@ -0,0 +1,93 @@
+import importlib
+from typing import Dict, List, Optional
+
+import pytest
+from langflow.utils.util import build_template_from_function, get_base_classes, get_default_factory
+from pydantic import BaseModel
+
+
+# Dummy classes for testing purposes
+class Parent(BaseModel):
+    """Parent Class"""
+
+    parent_field: str
+
+
+class Child(Parent):
+    """Child Class"""
+
+    child_field: int
+
+
+class ExampleClass1(BaseModel):
+    """Example class 1."""
+
+    def __init__(self, data: Optional[List[int]] = None):
+        self.data = data or [1, 2, 3]
+
+
+class ExampleClass2(BaseModel):
+    """Example class 2."""
+
+    def __init__(self, data: Optional[Dict[str, int]] = None):
+        self.data = data or {"a": 1, "b": 2, "c": 3}
+
+
+def example_loader_1() -> ExampleClass1:
+    """Example loader function 1."""
+    return ExampleClass1()
+
+
+def example_loader_2() -> ExampleClass2:
+    """Example loader function 2."""
+    return ExampleClass2()
+
+
+def test_build_template_from_function():
+    type_to_loader_dict = {
+        "example1": example_loader_1,
+        "example2": example_loader_2,
+    }
+
+    # Test with valid name
+    result = build_template_from_function("ExampleClass1", type_to_loader_dict)
+
+    assert result is not None
+    assert "template" in result
+    assert "description" in result
+    assert "base_classes" in result
+
+    # Test with add_function=True
+    result_with_function = build_template_from_function("ExampleClass1", type_to_loader_dict, add_function=True)
+    assert result_with_function is not None
+    assert "Callable" in result_with_function["base_classes"]
+
+    # Test with invalid name
+    with pytest.raises(ValueError, match=r".* not found"):
+        build_template_from_function("NonExistent", type_to_loader_dict)
+
+
+# Test get_base_classes
+def test_get_base_classes():
+    base_classes_parent = get_base_classes(Parent)
+    base_classes_child = get_base_classes(Child)
+
+    assert "Parent" in base_classes_parent
+    assert "Child" in base_classes_child
+    assert "Parent" in base_classes_child
+
+
+# Test get_default_factory
+def test_get_default_factory():
+    module_name = "langflow.utils.util"
+    function_repr = "<function dummy_function>"
+
+    def dummy_function():
+        return "default_value"
+
+    # Add dummy_function to your_module
+    setattr(importlib.import_module(module_name), "dummy_function", dummy_function)
+
+    default_value = get_default_factory(module_name, function_repr)
+
+    assert default_value == "default_value"