Issue Open-EO#668 add OpenEOCapabilities.get_federation to list feder…

…ation backends

openeo/rest/capabilities.py

@@ -1,4 +1,4 @@
-from typing import List, Optional, Union
+from typing import Dict, List, Optional, Union
 
 from openeo.internal.jupyter import render_component
 from openeo.util import deep_get
@@ -53,3 +53,13 @@ def list_plans(self) -> List[dict]:
 
     def _repr_html_(self):
         return render_component("capabilities", data=self.capabilities, parameters={"url": self.url})
+
+    def get_federation(self) -> Union[Dict[str, dict], None]:
+        """
+        Lists all back-ends (with details, such as URL) that are part of the federation
+        if this backend acts as a federated backend,
+        as specified in the openEO Federation Extension.
+        Returns ``None`` otherwise
+        """
+        # TODO: also check related conformance class in `/conformance`?
+        return self.get("federation")

tests/rest/test_capabilities.py

@@ -49,3 +49,20 @@ def test_list_plans(self):
         assert OpenEoCapabilities({"billing": None}).list_plans() == []
         assert OpenEoCapabilities({"billing": {"plans": []}}).list_plans() == []
         assert OpenEoCapabilities({"billing": {"plans": [{"name": "free"}]}}).list_plans() == [{"name": "free"}]
+
+    def test_federation_absent(self):
+        assert OpenEoCapabilities({}).get_federation() is None
+
+    def test_federation_present(self):
+        data = {
+            "api_version": "1.2.3",
+            "federation": {
+                "a": {"url": "https://a.test/openeo/v2", "title": "A backend"},
+                "bb": {"url": "https://openeo.b.test/v9"},
+            },
+        }
+        capabilities = OpenEoCapabilities(data)
+        assert capabilities.get_federation() == {
+            "a": {"url": "https://a.test/openeo/v2", "title": "A backend"},
+            "bb": {"url": "https://openeo.b.test/v9"},
+        }