[tune] Fix sort (#5111)

* fix sort

* fix tune list-experiments

* Update python/ray/tune/tests/test_commands.py

python/ray/tune/commands.py

@@ -163,8 +163,10 @@ def list_trials(experiment_path,
         checkpoints_df = checkpoints_df[filtered_index]
 
     if sort:
-        if sort not in checkpoints_df:
-            raise KeyError("{} not in: {}".format(sort, list(checkpoints_df)))
+        for key in sort:
+            if key not in checkpoints_df:
+                raise KeyError("{} not in: {}".format(key,
+                                                      list(checkpoints_df)))
         ascending = not desc
         checkpoints_df = checkpoints_df.sort_values(
             by=sort, ascending=ascending)
@@ -274,8 +276,9 @@ def list_experiments(project_path,
         info_df = info_df[filtered_index]
 
     if sort:
-        if sort not in info_df:
-            raise KeyError("{} not in: {}".format(sort, list(info_df)))
+        for key in sort:
+            if key not in info_df:
+                raise KeyError("{} not in: {}".format(key, list(info_df)))
         ascending = not desc
         info_df = info_df.sort_values(by=sort, ascending=ascending)
 

python/ray/tune/tests/test_commands.py

@@ -90,6 +90,7 @@ def test_ls(start_ray, tmpdir):
     with Capturing() as output:
         commands.list_trials(
             experiment_path,
+            sort=["status"],
             info_keys=("status", ),
             filter_op="status == TERMINATED")
     lines = output.captured
@@ -126,6 +127,7 @@ def test_lsx(start_ray, tmpdir):
     with Capturing() as output:
         commands.list_experiments(
             project_path,
+            sort=["total_trials"],
             info_keys=("total_trials", ),
             filter_op="total_trials == 1")
     lines = output.captured