🧪 test: add test for missing pandas import fallback in validate

pysus/api/validate.py

@@ -12,6 +12,11 @@
 
 from __future__ import annotations
 
+try:
+    import pandas as pd
+except ImportError:
+    pd = None
+
 from difflib import get_close_matches
 
 from pysus.api.errors import ValidationError

pysus/tests/api/test_validate.py

@@ -1,6 +1,10 @@
 """Tests for pysus.api.validate — input validation with suggestions."""
 
+import importlib
+import sys
+
 import pytest
+
 from pysus.api.errors import ValidationError
 from pysus.api.validate import (
     validate_choice,
@@ -9,6 +13,23 @@
 )
 
 
+def test_pandas_import_error_fallback(monkeypatch):
+    """Test that missing pandas falls back to pd = None."""
+    import pysus.api.validate
+    original_pd = pysus.api.validate.pd
+
+    monkeypatch.setitem(sys.modules, "pandas", None)
+
+    importlib.reload(pysus.api.validate)
+
+    assert pysus.api.validate.pd is None
+
+    # Clean up
+    monkeypatch.delitem(sys.modules, "pandas", raising=False)
+    importlib.reload(pysus.api.validate)
+    pysus.api.validate.pd = original_pd
+
+
 class TestValidateChoice:
     def test_exact_match(self):
         result = validate_choice("SINAN", ["SINAN", "SIA", "SIM"])