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_validate_code.py

@@ -0,0 +1,104 @@
+from pathlib import Path
+from unittest import mock
+
+import pytest
+from requests.exceptions import MissingSchema
+
+from langflow.utils.validate import create_function, execute_function, extract_function_name, validate_code
+
+
+def test_create_function():
+    code = """
+from pathlib import Path
+
+def my_function(x: str) -> Path:
+    return Path(x)
+"""
+
+    function_name = extract_function_name(code)
+    function = create_function(code, function_name)
+    result = function("test")
+    assert result == Path("test")
+
+
+def test_validate_code():
+    # Test case with a valid import and function
+    code1 = """
+import math
+
+def square(x):
+    return x ** 2
+"""
+    errors1 = validate_code(code1)
+    assert errors1 == {"imports": {"errors": []}, "function": {"errors": []}}
+
+    # Test case with an invalid import and valid function
+    code2 = """
+import non_existent_module
+
+def square(x):
+    return x ** 2
+"""
+    errors2 = validate_code(code2)
+    assert errors2 == {
+        "imports": {"errors": ["No module named 'non_existent_module'"]},
+        "function": {"errors": []},
+    }
+
+    # Test case with a valid import and invalid function syntax
+    code3 = """
+import math
+
+def square(x)
+    return x ** 2
+"""
+    errors3 = validate_code(code3)
+    assert errors3 == {
+        "imports": {"errors": []},
+        "function": {"errors": ["expected ':' (<unknown>, line 4)"]},
+    }
+
+
+def test_execute_function_success():
+    code = """
+import math
+
+def my_function(x):
+    return math.sin(x) + 1
+    """
+    result = execute_function(code, "my_function", 0.5)
+    assert result == 1.479425538604203
+
+
+def test_execute_function_missing_module():
+    code = """
+import some_missing_module
+
+def my_function(x):
+    return some_missing_module.some_function(x)
+    """
+    with pytest.raises(ModuleNotFoundError):
+        execute_function(code, "my_function", 0.5)
+
+
+def test_execute_function_missing_function():
+    code = """
+import math
+
+def my_function(x):
+    return math.some_missing_function(x)
+    """
+    with pytest.raises(AttributeError):
+        execute_function(code, "my_function", 0.5)
+
+
+def test_execute_function_missing_schema():
+    code = """
+import requests
+
+def my_function(x):
+    return requests.get(x).text
+    """
+    with mock.patch("requests.get", side_effect=MissingSchema):
+        with pytest.raises(MissingSchema):
+            execute_function(code, "my_function", "invalid_url")