diff --git a/src/openeo_aggregator/partitionedjobs/__init__.py b/src/openeo_aggregator/partitionedjobs/__init__.py
index 52fdc7b8..85671ba3 100644
--- a/src/openeo_aggregator/partitionedjobs/__init__.py
+++ b/src/openeo_aggregator/partitionedjobs/__init__.py
@@ -1,4 +1,4 @@
-from typing import NamedTuple, List, Dict, Sequence, Union, Any
+from typing import NamedTuple, List, Dict, Sequence, Union, Any, Optional
 
 from openeo_aggregator.utils import FlatPG, PGWithMetadata
 from openeo_driver.errors import OpenEOApiException
@@ -12,8 +12,8 @@ class SubJob(NamedTuple):
     """A part of a partitioned job, target at a particular, single back-end."""
     # Process graph of the subjob (derived in some way from original parent process graph)
     process_graph: FlatPG
-    # Id of target backend
-    backend_id: str
+    # Id of target backend (or None if there is no dedicated backend)
+    backend_id: Optional[str]
 
 
 class PartitionedJob(NamedTuple):
diff --git a/src/openeo_aggregator/partitionedjobs/crossbackend.py b/src/openeo_aggregator/partitionedjobs/crossbackend.py
index 0941a43b..18905bda 100644
--- a/src/openeo_aggregator/partitionedjobs/crossbackend.py
+++ b/src/openeo_aggregator/partitionedjobs/crossbackend.py
@@ -1,6 +1,5 @@
 import collections
 import logging
-from pprint import pprint
 from typing import Callable, Dict, List
 
 from openeo_aggregator.partitionedjobs import SubJob, PartitionedJob
@@ -35,7 +34,7 @@ def split(
             f"Extracted backend usage from `load_collection` nodes: {backend_usage}"
         )
 
-        primary_backend = backend_usage.most_common(1)[0][0]
+        primary_backend = backend_usage.most_common(1)[0][0] if backend_usage else None
         secondary_backends = {b for b in backend_usage if b != primary_backend}
         _log.info(f"Backend split: {primary_backend=} {secondary_backends=}")
 
@@ -80,45 +79,3 @@ def split(
             subjobs=PartitionedJob.to_subjobs_dict(subjobs),
             dependencies=dependencies,
         )
-
-
-def main():
-    # Simple proof of concept for cross-backend splitting
-    process_graph = {
-        "lc1": {"process_id": "load_collection", "arguments": {"id": "VITO_1"}},
-        "lc2": {"process_id": "load_collection", "arguments": {"id": "SH_1"}},
-        "mc1": {
-            "process_id": "merge_cubes",
-            "arguments": {"cube1": {"from_node": "lc1"}, "cube2": {"from_node": "lc2"}},
-        },
-        "sr1": {
-            "process_id": "save_result",
-            "arguments": {"format": "NetCDF"},
-        },
-    }
-    print("Original PG:")
-    pprint(process_graph)
-
-    splitter = CrossBackendSplitter(
-        backend_for_collection=lambda cid: cid.split("_")[0]
-    )
-
-    pjob = splitter.split({"process_graph": process_graph})
-
-    def namedtuples_to_dict(x):
-        """Walk data structure and convert namedtuples to dictionaries"""
-        if hasattr(x, "_asdict"):
-            return namedtuples_to_dict(x._asdict())
-        elif isinstance(x, list):
-            return [namedtuples_to_dict(i) for i in x]
-        elif isinstance(x, dict):
-            return {k: namedtuples_to_dict(v) for k, v in x.items()}
-        else:
-            return x
-
-    print("Cross-backend split:")
-    pprint(namedtuples_to_dict(pjob), width=120)
-
-
-if __name__ == "__main__":
-    main()
diff --git a/tests/partitionedjobs/test_crossbackend.py b/tests/partitionedjobs/test_crossbackend.py
new file mode 100644
index 00000000..f34dabc0
--- /dev/null
+++ b/tests/partitionedjobs/test_crossbackend.py
@@ -0,0 +1,78 @@
+from openeo_aggregator.partitionedjobs import SubJob
+from openeo_aggregator.partitionedjobs.crossbackend import (
+    CrossBackendSplitter,
+)
+
+
+class TestCrossBackendSplitter:
+    def test_simple(self):
+        process_graph = {
+            "add": {"process_id": "add", "arguments": {"x": 3, "y": 5}, "result": True}
+        }
+        splitter = CrossBackendSplitter(backend_for_collection=lambda cid: "foo")
+        res = splitter.split({"process_graph": process_graph})
+
+        assert res.subjobs == {"primary": SubJob(process_graph, backend_id=None)}
+        assert res.dependencies == {"primary": []}
+
+    def test_basic(self):
+        process_graph = {
+            "lc1": {"process_id": "load_collection", "arguments": {"id": "B1_NDVI"}},
+            "lc2": {"process_id": "load_collection", "arguments": {"id": "B2_FAPAR"}},
+            "mc1": {
+                "process_id": "merge_cubes",
+                "arguments": {
+                    "cube1": {"from_node": "lc1"},
+                    "cube2": {"from_node": "lc2"},
+                },
+            },
+            "sr1": {
+                "process_id": "save_result",
+                "arguments": {"format": "NetCDF"},
+            },
+        }
+        splitter = CrossBackendSplitter(
+            backend_for_collection=lambda cid: cid.split("_")[0]
+        )
+        res = splitter.split({"process_graph": process_graph})
+
+        assert res.subjobs == {
+            "primary": SubJob(
+                process_graph={
+                    "lc1": {
+                        "process_id": "load_collection",
+                        "arguments": {"id": "B1_NDVI"},
+                    },
+                    "lc2": {
+                        "process_id": "load_result",
+                        "arguments": {"id": "placeholder:B2:lc2"},
+                    },
+                    "mc1": {
+                        "process_id": "merge_cubes",
+                        "arguments": {
+                            "cube1": {"from_node": "lc1"},
+                            "cube2": {"from_node": "lc2"},
+                        },
+                    },
+                    "sr1": {
+                        "process_id": "save_result",
+                        "arguments": {"format": "NetCDF"},
+                    },
+                },
+                backend_id="B1",
+            ),
+            "B2:lc2": SubJob(
+                process_graph={
+                    "lc2": {
+                        "process_id": "load_collection",
+                        "arguments": {"id": "B2_FAPAR"},
+                    },
+                    "sr1": {
+                        "process_id": "save_result",
+                        "arguments": {"format": "NetCDF"},
+                    },
+                },
+                backend_id="B2",
+            ),
+        }
+        assert res.dependencies == {"primary": ["B2:lc2"]}