EP-4012: add support for process graph validation

Author: soxofaan

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add proper support for child callbacks in `fit_curve` and `predict_curve` ([#229](https://github.com/Open-EO/openeo-python-client/issues/229))
 - `ProcessBuilder`: Add support for `array_element(data, n)` through `data[n]` syntax ([#228](https://github.com/Open-EO/openeo-python-client/issues/228))
 - `ProcessBuilder`: Add support for `eq` and `neq` through `==` and `!=` operators (EP-4011)
+- Add `DataCube.validate()` for process graph validation (EP-4012 related)
 
 
 ### Changed

openeo/rest/connection.py

@@ -753,9 +753,15 @@ def user_defined_process(self, user_defined_process_id: str) -> RESTUserDefinedP
         """
         return RESTUserDefinedProcess(user_defined_process_id=user_defined_process_id, connection=self)
 
-    def validate_processgraph(self, process_graph):
-        # Endpoint: POST /validate
-        raise NotImplementedError()
+    def validate_process_graph(self, process_graph: dict) -> List[dict]:
+        """
+        Validate a process graph without executing it.
+
+        :param process_graph: (flat) dict representing process graph
+        :return: list of errors (dictionaries with "code" and "message" fields)
+        """
+        request = {"process_graph": process_graph}
+        return self.post(path="/validation", json=request, expected_status=200).json()["errors"]
 
     @property
     def _api_version(self) -> ComparableVersion:

openeo/rest/datacube.py

@@ -1483,6 +1483,14 @@ def download(self, outputfile: Union[str, pathlib.Path, None] = None, format: st
         cube = self.save_result(format=format, options=options)
         return self._connection.download(cube.flat_graph(), outputfile)
 
+    def validate(self) -> List[dict]:
+        """
+        Validate a process graph without executing it.
+
+        :return: list of errors (dictionaries with "code" and "message" fields)
+        """
+        return self._connection.validate_process_graph(self.flat_graph())
+
     def tiled_viewing_service(self, type: str, **kwargs) -> Service:
         return self._connection.create_service(self.flat_graph(), type=type, **kwargs)
 

tests/rest/datacube/test_datacube100.py

@@ -1271,3 +1271,22 @@ def model(x, parameters):
         },
     }
     assert res.graph == expected
+
+
+def test_validation(con100, requests_mock):
+    def validation(request, context):
+        assert request.json() == {"process_graph": {
+            'loadcollection1': {
+                'process_id': 'load_collection',
+                'arguments': {'id': 'S2', 'spatial_extent': None, 'temporal_extent': None},
+                'result': True,
+            }
+        }}
+        return {"errors": [{"code": "Invalid", "message": "Invalid process graph"}]}
+
+    m = requests_mock.post(API_URL + "/validation", json=validation)
+
+    cube = con100.load_collection("S2")
+    errors = cube.validate()
+    assert errors == [{"code": "Invalid", "message": "Invalid process graph"}]
+    assert m.call_count == 1