Update test to load from HF Hub

test/test_invariants.py

@@ -2,14 +2,14 @@
 Invariant tests for cterdam/iata-metro dataset.
 
 Run from dataset root after cloning:
+    pip install datasets pytest
     pytest test/test_invariants.py -v
 
 Verifies:
 - name field matches lang selection (name_en/ru/zh)
 - hash = SHA256(name)
-- lang matches region's language rule
+- lang matches region-based language rule
 - hash format is 64-char hex string
-- coordinates are valid (if present)
 """
 
 import hashlib
@@ -26,11 +26,11 @@ SINOPHONE_REGIONS = {
 }
 
 
-def determine_expected_lang(region: str) -> str:
+def determine_expected_lang(region_code: str) -> str:
     """Determine expected lang from region code."""
-    if region in SINOPHONE_REGIONS:
+    if region_code in SINOPHONE_REGIONS:
         return 'zh'
-    elif region in SLAVIC_REGIONS:
+    elif region_code in SLAVIC_REGIONS:
         return 'ru'
     else:
         return 'en'
@@ -38,7 +38,8 @@ def determine_expected_lang(region: str) -> str:
 
 @pytest.fixture(scope="session")
 def dataset():
-    return load_dataset('.', split='train')
+    """Load dataset from HF Hub."""
+    return load_dataset('cterdam/iata-metro', split='train')
 
 
 def test_lang_values_valid(dataset):
@@ -114,7 +115,7 @@ def test_lang_matches_region(dataset):
             if len(mismatches) >= 5:
                 break
     
-    assert mismatches == [], f"Lang mismatches: {mismatches}"
+    assert mismatches == [], f"Lang mismatches: {{mismatches}}"
 
 
 def test_coordinates_valid(dataset):
@@ -125,4 +126,5 @@ def test_coordinates_valid(dataset):
         if (e.get('lat') is not None and (e['lat'] < -90 or e['lat'] > 90)) or
            (e.get('lon') is not None and (e['lon'] < -180 or e['lon'] > 180))
     ]
-    assert invalid == [], f"Invalid coordinates: {invalid[:5]}"
+    assert invalid == [], f"Invalid coordinates: {{invalid[:5]}}"
+