Add warning for future change of argument name for timeseries from asel -> atomgroup

package/CHANGELOG

@@ -59,6 +59,8 @@ Changes
     `analysis.nucleicacids.WatsonCrickDist.results.distances` (Issue #3720, PR #3735)
 
 Deprecations
+  * The `asel` argument to timeseries will be renamed to `atomgroup` in 3.0.0.
+    (Issue #3911)
   * MDAnalysis.lib.util is deprecated and will be removed in version 3.0
     (Issue #3649)
   * The TRZ reader & writer are deprecated and will be removed in version 3.0

package/MDAnalysis/coordinates/DCD.py

@@ -315,6 +315,11 @@ def timeseries(self,
             ValueError now raised instead of NoDataError for empty input
             AtomGroup
         """
+        if asel:
+            warnings.warn(
+                "asel argument to timeseries will be renamed to"
+                "'atomgroup' in 3.0, see #3911",
+                category=DeprecationWarning)
 
         start, stop, step = self.check_slice_indices(start, stop, step)
 

package/MDAnalysis/coordinates/base.py

@@ -1023,6 +1023,12 @@ def timeseries(self, asel: Optional['AtomGroup']=None,
 
         .. versionadded:: 2.4.0
         """
+        if asel:
+            warnings.warn(
+                "asel argument to timeseries will be renamed to"
+                "'atomgroup' in 3.0, see #3911",
+                category=DeprecationWarning)
+
         start, stop, step = self.check_slice_indices(start, stop, step)
         nframes = len(range(start, stop, step))
 

package/MDAnalysis/coordinates/memory.py

@@ -525,6 +525,12 @@ def timeseries(self, asel=None, start=0, stop=-1, step=1, order='afc'):
             ValueError now raised instead of NoDataError for empty input
             AtomGroup
         """
+        if asel:
+            warnings.warn(
+                "asel argument to timeseries will be renamed to"
+                "'atomgroup' in 3.0, see #3911",
+                category=DeprecationWarning)
+
         if stop != -1:
             warnings.warn("MemoryReader.timeseries inclusive `stop` "
                       "indexing will be removed in 3.0 in favour of exclusive "

testsuite/MDAnalysisTests/coordinates/base.py

@@ -501,6 +501,12 @@ def test_timeseries_empty_asel(self, reader):
         with pytest.raises(ValueError, match="Timeseries requires at least"):
             reader.timeseries(atoms)
 
+    def test_timeseries_asel_warns_deprecation(self, reader):
+        atoms = mda.Universe(reader.filename).select_atoms("index 1")
+        with pytest.warns(DeprecationWarning, match="asel argument to"):
+            timeseries = reader.timeseries(asel=atoms, order='fac')
+
+
 class MultiframeReaderTest(BaseReaderTest):
     def test_last_frame(self, ref, reader):
         ts = reader[-1]

testsuite/MDAnalysisTests/coordinates/test_dcd.py

@@ -236,7 +236,12 @@ def test_timeseries_empty_selection(universe_dcd):
         asel = universe_dcd.select_atoms('name FOO')
         universe_dcd.trajectory.timeseries(asel=asel)
 
-
+def test_timeseries_asel_warns_deprecation(universe_dcd):
+    allframes = universe_dcd.trajectory.timeseries(order='afc')
+    asel = universe_dcd.atoms[[1, 2, 3, 4]]
+    with pytest.warns(DeprecationWarning, match="asel argument to"):
+        xyz = universe_dcd.trajectory.timeseries(asel=asel, order='afc')
+
 def test_reader_set_dt():
     dt = 100
     frame = 3

testsuite/MDAnalysisTests/coordinates/test_memory.py

@@ -202,6 +202,11 @@ def test_timeseries_warns_deprecation(self, reader):
                           "inclusive"):
             reader.timeseries(start=0, stop=3, step=1)
 
+    def test_timeseries_asel_warns_deprecation(self, ref, reader):
+        selection = ref.universe.atoms
+        with pytest.warns(DeprecationWarning, match="asel argument to"):
+            reader.timeseries(asel=selection)
+
 
 class TestMemoryReaderVelsForces(object):
     @staticmethod