Fix FeatureCollection item validation

geojson/feature.py

@@ -50,10 +50,16 @@ def __init__(self, features, **extra):
         ]
 
     def errors(self):
-        return self.check_list_errors(lambda x: x.errors(), self.features)
+        return self.check_list_errors(_feature_errors, self.features)
 
     def __getitem__(self, key):
         try:
             return self.get("features", ())[key]
         except (KeyError, TypeError, IndexError):
             return super(GeoJSON, self).__getitem__(key)
+
+
+def _feature_errors(feature):
+    if not isinstance(feature, Feature):
+        return "FeatureCollection features must be Features"
+    return feature.errors()

tests/test_validation.py

@@ -193,3 +193,31 @@ def test_valid_geometrycollection(self):
                 geometries=[point, poly]
             )
         self.assertTrue(geom_collection.is_valid)
+
+
+class TestValidationFeatureCollection(unittest.TestCase):
+
+    def test_featurecollection_rejects_geometry_items(self):
+        collection = geojson.FeatureCollection([geojson.Point((0, 0))])
+
+        self.assertFalse(collection.is_valid)
+        self.assertIn("FeatureCollection features must be Features",
+                      collection.errors())
+
+    def test_featurecollection_rejects_nested_featurecollections(self):
+        collection = geojson.FeatureCollection([
+            geojson.FeatureCollection([
+                geojson.Feature(geometry=geojson.Point((0, 0)))
+            ])
+        ])
+
+        self.assertFalse(collection.is_valid)
+        self.assertIn("FeatureCollection features must be Features",
+                      collection.errors())
+
+    def test_valid_featurecollection(self):
+        collection = geojson.FeatureCollection([
+            geojson.Feature(geometry=geojson.Point((0, 0)))
+        ])
+
+        self.assertTrue(collection.is_valid)