from_global_id should work same as in relay-js (#39)

Author: Cito

Diff for: src/graphql_relay/node/node.py

@@ -92,7 +92,10 @@ def from_global_id(global_id: str) -> ResolvedGlobalId:
     Takes the "global ID" created by to_global_id, and returns the type name and ID
     used to create it.
     """
-    return ResolvedGlobalId(*unbase64(global_id).split(":", 1))
+    global_id = unbase64(global_id)
+    if ":" not in global_id:
+        return ResolvedGlobalId("", global_id)
+    return ResolvedGlobalId(*global_id.split(":", 1))
 
 
 def global_id_field(

Diff for: tests/node/test_global.py

@@ -202,3 +202,15 @@ def allows_to_refetch_the_ids(schema):
             },
             None,
         )
+
+    def handles_valid_global_ids():
+        assert from_global_id("Zm9v") == ("", "foo")
+        assert from_global_id(b"Zm9v") == ("", "foo")  # type: ignore
+        assert from_global_id("Zm9vOmJhcg==") == ("foo", "bar")
+        assert from_global_id(b"Zm9vOmJhcg==") == ("foo", "bar")  # type: ignore
+
+    def handles_invalid_global_ids():
+        assert from_global_id("") == ("", "")
+        assert from_global_id("Og==") == ("", "")
+        assert from_global_id("bad!") == ("", "")
+        assert from_global_id("invalid") == ("", "")