Add testcase for mapped over discovered dataset consumption

test/api/test_workflows.py

@@ -1130,6 +1130,41 @@ steps:
             assert len(identifiers) == 6
             assert "oe1-ie1" in identifiers
 
+    @skip_without_tool("collection_paired_test")
+    def test_workflow_flatten_with_mapped_over_execution(self):
+        with self.dataset_populator.test_history() as history_id:
+            self._run_jobs(r"""
+class: GalaxyWorkflow
+inputs:
+  input_fastqs: collection
+steps:
+  split_up:
+    tool_id: collection_split_on_column
+    in:
+      input1: input_fastqs
+  flatten:
+    tool_id: '__FLATTEN__'
+    in:
+      input: split_up/split_output
+    join_identifier: '-'
+test_data:
+  input_fastqs:
+    type: list
+    elements:
+      - identifier: samp1
+        content: "0\n1"
+""", history_id=history_id)
+            history = self._get('histories/%s/contents' % history_id).json()
+            flattened_collection = history[-1]
+            assert flattened_collection['history_content_type'] == 'dataset_collection'
+            assert flattened_collection['collection_type'] == 'list'
+            assert flattened_collection['element_count'] == 2
+            nested_collection = self.dataset_populator.get_history_collection_details(history_id, hid=3)
+            assert nested_collection['collection_type'] == 'list:list'
+            assert nested_collection['element_count'] == 1
+            assert nested_collection['elements'][0]['object']['populated']
+            assert nested_collection['elements'][0]['object']['element_count'] == 2
+
     @skip_without_tool("__APPLY_RULES__")
     def test_workflow_run_apply_rules(self):
         with self.dataset_populator.test_history() as history_id: