Add test case clarifying datasets do get "renamed" by rename PJA in c…

…ollections.

xref galaxyproject#1675

This is of limited utility since we don't really expose the name - and intentionally so. Related open bugs/enhancements that still need to be addressed are:

 - Applying rename to the collection (in addition to the elements) - galaxyproject#1680.
 - Download of collection elements with element identifier instead of the name: galaxyproject#2023 / galaxyproject#2140.

test/api/test_workflows.py

@@ -1289,6 +1289,37 @@ def test_run_with_pja( self ):
         content = self.dataset_populator.get_history_dataset_details( history_id, wait=True, assert_ok=True )
         assert content[ "name" ] == "foo was replaced"
 
+    @skip_without_tool( "cat" )
+    def test_run_rename_collection_element( self ):
+        history_id = self.dataset_populator.new_history()
+        self._run_jobs("""
+class: GalaxyWorkflow
+inputs:
+  - id: input1
+    type: data_collection_input
+    collection_type: list
+steps:
+  - tool_id: cat
+    label: first_cat
+    state:
+      input1:
+        $link: input1
+    outputs:
+      out_file1:
+        rename: "my new name"
+test_data:
+  input1:
+    type: list
+    name: the_dataset_list
+    elements:
+      - identifier: el1
+        value: 1.fastq
+        type: File
+""", history_id=history_id)
+        content = self.dataset_populator.get_history_dataset_details( history_id, hid=3, wait=True, assert_ok=True )
+        name = content[ "name" ]
+        assert name == "my new name", name
+
     @skip_without_tool( "cat" )
     def test_run_rename_based_on_input( self ):
         history_id = self.dataset_populator.new_history()