Add union link connection type support (#5806)

* Add union type support

* Move code

* nit

tests-unit/execution_test/validate_node_input_test.py

@@ -0,0 +1,75 @@
+import pytest
+from comfy_execution.validation import validate_node_input
+
+
+def test_exact_match():
+    """Test cases where types match exactly"""
+    assert validate_node_input("STRING", "STRING")
+    assert validate_node_input("STRING,INT", "STRING,INT")
+    assert (
+        validate_node_input("INT,STRING", "STRING,INT")
+    )  # Order shouldn't matter
+
+
+def test_strict_mode():
+    """Test strict mode validation"""
+    # Should pass - received type is subset of input type
+    assert validate_node_input("STRING", "STRING,INT", strict=True)
+    assert validate_node_input("INT", "STRING,INT", strict=True)
+    assert validate_node_input("STRING,INT", "STRING,INT,BOOLEAN", strict=True)
+
+    # Should fail - received type is not subset of input type
+    assert not validate_node_input("STRING,INT", "STRING", strict=True)
+    assert not validate_node_input("STRING,BOOLEAN", "STRING", strict=True)
+    assert not validate_node_input("INT,BOOLEAN", "STRING,INT", strict=True)
+
+
+def test_non_strict_mode():
+    """Test non-strict mode validation (default behavior)"""
+    # Should pass - types have overlap
+    assert validate_node_input("STRING,BOOLEAN", "STRING,INT")
+    assert validate_node_input("STRING,INT", "INT,BOOLEAN")
+    assert validate_node_input("STRING", "STRING,INT")
+
+    # Should fail - no overlap in types
+    assert not validate_node_input("BOOLEAN", "STRING,INT")
+    assert not validate_node_input("FLOAT", "STRING,INT")
+    assert not validate_node_input("FLOAT,BOOLEAN", "STRING,INT")
+
+
+def test_whitespace_handling():
+    """Test that whitespace is handled correctly"""
+    assert validate_node_input("STRING, INT", "STRING,INT")
+    assert validate_node_input("STRING,INT", "STRING, INT")
+    assert validate_node_input(" STRING , INT ", "STRING,INT")
+    assert validate_node_input("STRING,INT", " STRING , INT ")
+
+
+def test_empty_strings():
+    """Test behavior with empty strings"""
+    assert validate_node_input("", "")
+    assert not validate_node_input("STRING", "")
+    assert not validate_node_input("", "STRING")
+
+
+def test_single_vs_multiple():
+    """Test single type against multiple types"""
+    assert validate_node_input("STRING", "STRING,INT,BOOLEAN")
+    assert validate_node_input("STRING,INT,BOOLEAN", "STRING", strict=False)
+    assert not validate_node_input("STRING,INT,BOOLEAN", "STRING", strict=True)
+
+
+@pytest.mark.parametrize(
+    "received,input_type,strict,expected",
+    [
+        ("STRING", "STRING", False, True),
+        ("STRING,INT", "STRING,INT", False, True),
+        ("STRING", "STRING,INT", True, True),
+        ("STRING,INT", "STRING", True, False),
+        ("BOOLEAN", "STRING,INT", False, False),
+        ("STRING,BOOLEAN", "STRING,INT", False, True),
+    ],
+)
+def test_parametrized_cases(received, input_type, strict, expected):
+    """Parametrized test cases for various scenarios"""
+    assert validate_node_input(received, input_type, strict) == expected