added migration from 1.1 to 1.2

Author: jonas-hurst

pystac/extensions/mlm.py

@@ -2092,7 +2092,18 @@ def _migrate_1_0_to_1_1(obj: dict[str, Any]) -> None:
 
     @staticmethod
     def _migrate_1_1_to_1_2(obj: dict[str, Any]) -> None:
-        pass
+        if "assets" not in obj:
+            return
+        assets = obj["assets"]
+        model_in_assets = any(
+            ["mlm:model" in assets[asset]["roles"] for asset in assets]
+        )
+        if not model_in_assets:
+            raise pystac.errors.STACError(
+                'Error migrating stac:mlm version: An asset with role "mlm:model" is '
+                "required in mlm>=1.2. Include at least one asset with role "
+                '"mlm:model" '
+            )
 
     @staticmethod
     def _migrate_1_2_to_1_3(obj: dict[str, Any]) -> None:

tests/extensions/test_mlm.py

@@ -1107,6 +1107,20 @@ def test_migration_1_0_to_1_1(
     assert bool(re.match(pattern, data["properties"]["mlm:framework"]))
 
 
+def test_migration_1_1_to_1_2() -> None:
+    data: dict[str, Any] = {}
+    MLMExtensionHooks._migrate_1_1_to_1_2(data)
+
+    data["assets"] = {"asset1": {"roles": ["data"]}, "asset2": {"roles": ["labels"]}}
+
+    with pytest.raises(pystac.errors.STACError):
+        MLMExtensionHooks._migrate_1_1_to_1_2(data)
+
+    data["assets"]["asset3"] = {"roles": ["mlm:model"]}
+
+    MLMExtensionHooks._migrate_1_1_to_1_2(data)
+
+
 @pytest.mark.parametrize(
     ("norm_by_channel", "norm_type", "norm_clip", "statistics", "value_scaling"),
     (