allow empty list to be a command/entrypoint

Signed-off-by: Sergei Biriukov <svbiriukov@gmail.com>

podman_compose.py

@@ -63,8 +63,6 @@ def is_list(list_object):
 
 def is_list_of_str(list_of_str_object):
     if is_list(list_of_str_object):
-        if len(list_of_str_object) == 0:
-            return False
         for element in list_of_str_object:
             if not is_str(element):
                 return False

pytests/test_is_list_of_str.py

@@ -2,9 +2,9 @@ from podman_compose import is_list_of_str
 
 
 def test_is_list_of_str():
+    assert is_list_of_str([])
     assert is_list_of_str(["foo", "bar"])
     assert not is_list_of_str(["foo", 1])
     assert not is_list_of_str("foo")
-    assert not is_list_of_str([])
     assert not is_list_of_str(1)
     assert not is_list_of_str(None)

pytests/test_rec_merge_one_cmd_ent.py

@@ -6,6 +6,10 @@ from podman_compose import rec_merge_one
 
 test_keys = ["command", "entrypoint"]
 test_cases = [
+    ({}, {"$$$": []}, {"$$$": []}),
+    ({"$$$": []}, {}, {"$$$": []}),
+    ({"$$$": []}, {"$$$": "sh-2"}, {"$$$": ["sh-2"]}),
+    ({"$$$": "sh-2"}, {"$$$": []}, {"$$$": []}),
     ({}, {"$$$": "sh"}, {"$$$": ["sh"]}),
     ({"$$$": "sh"}, {}, {"$$$": ["sh"]}),
     ({"$$$": "sh-1"}, {"$$$": "sh-2"}, {"$$$": ["sh-2"]}),
@@ -30,9 +34,6 @@ test_cases_with_exceptions = [
     ({"$$$": {}}, {}, ValueError),
     ({}, {"$$$": {}}, ValueError),
     ({"$$$": {}}, {"$$$": {}}, ValueError),
-    ({"$$$": []}, {}, ValueError),
-    ({}, {"$$$": []}, ValueError),
-    ({"$$$": []}, {"$$$": []}, ValueError),
 ]