Added stricter controls over the returned values by the datasource

force_bdss/core_evaluation_driver.py

@@ -3,6 +3,7 @@ import logging
 
 from traits.api import on_trait_change
 
+from force_bdss.core.data_value import DataValue
 from force_bdss.ids import InternalPluginID
 from .base_core_driver import BaseCoreDriver
 
@@ -142,6 +143,17 @@ def _compute_layer_results(environment_data_values,
                 "Run method raised exception.")
             raise
 
+        if not isinstance(res, list):
+            error_txt = (
+                "The run method of data source {} must return a list." 
+                " It returned instead {}. Fix the run() method to return"
+                " the appropriate entity.".format(
+                    factory.name,
+                    type(res)
+                ))
+            log.error(error_txt)
+            raise RuntimeError(error_txt)
+
         if len(res) != len(out_slots):
             error_txt = (
                 "The number of data values ({} values) returned"
@@ -169,6 +181,23 @@ def _compute_layer_results(environment_data_values,
             log.error(error_txt)
             raise RuntimeError(error_txt)
 
+        for idx, dv in enumerate(res):
+            if not isinstance(dv, DataValue):
+                error_txt = (
+                    "The result list returned by DataSource {} contains"
+                    " an entry that is not a DataValue. An entry of type"
+                    " {} was instead found in position {}."
+                    " Fix the DataSource.run() method"
+                    " to return the appropriate entity.".format(
+                        factory.name,
+                        type(dv),
+                        idx
+                    )
+                )
+                log.error(error_txt)
+                raise RuntimeError(error_txt)
+
+
         # At this point, the returned data values are unnamed.
         # Add the names as specified by the user.
         for dv, output_slot_info in zip(res, model.output_slot_info):

force_bdss/tests/test_core_evaluation_driver.py

@@ -77,6 +77,40 @@ class TestCoreEvaluationDriver(unittest.TestCase):
                     " the number of output slots"):
                 driver.application_started()
 
+    def test_error_for_incorrect_return_type(self):
+        def run(self, *args, **kwargs):
+            return "hello"
+        ds_factory = self.registry.data_source_factories[0]
+        ds_factory.run_function = run
+        driver = CoreEvaluationDriver(application=self.mock_application)
+        with testfixtures.LogCapture():
+            with six.assertRaisesRegex(
+                    self,
+                    RuntimeError,
+                    "The run method of data source test_data_source must"
+                    " return a list. It returned instead <type 'str'>. Fix"
+                    " the run\(\) method to return the appropriate entity."):
+                driver.application_started()
+
+    def test_error_for_incorrect_data_value_entries(self):
+        def run(self, *args, **kwargs):
+            return ["hello"]
+        ds_factory = self.registry.data_source_factories[0]
+        ds_factory.run_function = run
+        driver = CoreEvaluationDriver(application=self.mock_application)
+        with testfixtures.LogCapture():
+            with six.assertRaisesRegex(
+                    self,
+                    RuntimeError,
+                    "The result list returned by DataSource test_data_source"
+                    " contains an entry that is not a DataValue."
+                    " An entry of type <type 'str'> was instead found"
+                    " in position 0."
+                    " Fix the DataSource.run\(\) method to"
+                    " return the appropriate entity."
+                    ):
+                driver.application_started()
+
     def test_error_for_missing_ds_output_names(self):
 
         def run(self, *args, **kwargs):