Add more tests to the number of users being removed

elvis.config

@@ -22,7 +22,7 @@
               {elvis_style, invalid_dynamic_call, #{ignore => [amoc_code_server_SUITE]}},
               {elvis_style, dont_repeat_yourself, #{min_complexity => 50}},
               {elvis_style, no_debug_call, disable},
-              {elvis_style, no_block_expressions, #{ignore => [amoc_code_server_SUITE]}},
+              {elvis_style, no_block_expressions, #{ignore => [amoc_code_server_SUITE, controller_SUITE]}},
               {elvis_style, no_throw, disable},
               {elvis_style, no_import, disable}
           ]},

src/users/amoc_users_sup.erl

@@ -19,10 +19,10 @@
 -export([incr_no_of_users/1, decr_no_of_users/1, count_no_of_users/0,
          start_child/3, stop_child/2, start_children/3, stop_children/2, terminate_all_children/0]).
 
--export([get_all_children/0]).
+-export([distribute/2, get_all_children/0]).
 
 -type count() :: non_neg_integer().
--type assignment() ::[{pid(), count()}].
+-type assignment() :: [{pid(), count()}].
 
 -record(storage, {
           %% an array of atomics whose index works as follows:

test/controller_SUITE.erl

@@ -1,18 +1,29 @@
 -module(controller_SUITE).
 -compile([export_all, nowarn_export_all]).
 
+-include_lib("proper/include/proper.hrl").
 -include_lib("stdlib/include/assert.hrl").
 
 all() ->
     [
+     {group, distribute},
      {group, all_tests}
     ].
 
 groups() ->
     [
+     {distribute, [parallel], distribute()},
      {all_tests, [], all_tests()}
     ].
 
+distribute() ->
+    [
+     each_assignment_is_less_than_or_equal_in_the_input,
+     total_count_is_always_less_than_or_equal_the_requested_amount,
+     total_count_is_equal_to_the_requested_amount_or_the_sum_of_values_in_the_input,
+     total_count_is_the_exact_sum_of_the_values_in_the_input
+    ].
+
 all_tests() ->
     [
      no_scenario_running_status_is_idle,
@@ -28,6 +39,7 @@ all_tests() ->
      remove_users_scenario_not_started_fails,
      check_status_with_running_users_is_correct,
      check_status_after_killing_one_user_is_correct,
+     check_status_after_killing_many_users_is_correct,
      killing_more_users_than_available_is_correct,
      killing_many_users_in_a_big_test_is_correct,
      stop_non_running_scenario_fails,
@@ -57,6 +69,47 @@ end_per_testcase(_TestCase, Config) ->
     Config.
 
 %% test cases
+
+each_assignment_is_less_than_or_equal_in_the_input(_) ->
+    Prop = ?FORALL({Total, Counts}, {pos_integer(), sups_with_counts()},
+              begin
+                  SupervisorWithCounts = [ {dummy_pid(), Count} || Count <- Counts ],
+                  {_, Assignments} = amoc_users_sup:distribute(Total, SupervisorWithCounts),
+                  Data = maps:from_list(SupervisorWithCounts),
+                  lists:all(fun({Pid, N}) -> N =< maps:get(Pid, Data) end, Assignments)
+              end),
+    run_prop(?FUNCTION_NAME, Prop, 100, 1).
+
+total_count_is_always_less_than_or_equal_the_requested_amount(_) ->
+    Prop = ?FORALL({Total, Counts}, {pos_integer(), sups_with_counts()},
+              begin
+                  SupervisorWithCounts = [ {dummy_pid(), Count} || Count <- Counts ],
+                  {Count, _} = amoc_users_sup:distribute(Total, SupervisorWithCounts),
+                  Count =< Total
+              end),
+    run_prop(?FUNCTION_NAME, Prop, 100, 1).
+
+total_count_is_equal_to_the_requested_amount_or_the_sum_of_values_in_the_input(_) ->
+    Prop = ?FORALL({Total, Counts}, {pos_integer(), sups_with_counts()},
+              begin
+                  SupervisorWithCounts = [ {dummy_pid(), Count} || Count <- Counts ],
+                  {Count, Assignments} = amoc_users_sup:distribute(Total, SupervisorWithCounts),
+                  Assinged = lists:sum([ N || {_, N} <- Assignments ]),
+                  Count =:= Total orelse Count =:= Assinged
+              end),
+    run_prop(?FUNCTION_NAME, Prop, 100, 1).
+
+% • The total count of the users is the exact sum of the values in the KV list
+total_count_is_the_exact_sum_of_the_values_in_the_input(_) ->
+    Prop = ?FORALL({Total, Counts}, {pos_integer(), sups_with_counts()},
+              begin
+                  SupervisorWithCounts = [ {dummy_pid(), Count} || Count <- Counts ],
+                  {Count, Assignments} = amoc_users_sup:distribute(Total, SupervisorWithCounts),
+                  Assinged = lists:sum([ N || {_, N} <- Assignments ]),
+                  Count =:= Assinged
+              end),
+    run_prop(?FUNCTION_NAME, Prop, 100, 1).
+
 no_scenario_running_status_is_idle(_) ->
     Status = amoc_controller:get_status(),
     ?assertMatch(idle, Status).
@@ -119,31 +172,16 @@ check_status_with_running_users_is_correct(_) ->
     test_helpers:wait_until_scenario_has_users(testing_scenario, EndId - StartId + 1, EndId).
 
 check_status_after_killing_one_user_is_correct(_) ->
-    do_start_scenario(testing_scenario, test_helpers:regular_vars()),
-    NumOfUsers = 10,
-    amoc_controller:add_users(1, NumOfUsers),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, NumOfUsers, NumOfUsers),
-    Ret = amoc_controller:remove_users(1, true),
-    ?assertMatch({ok, 1}, Ret),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, NumOfUsers - 1, NumOfUsers).
+    start_and_remove_some_users(10, 1, 1, 9).
+
+check_status_after_killing_many_users_is_correct(_) ->
+    start_and_remove_some_users(10, 7, 7, 3).
 
 killing_more_users_than_available_is_correct(_) ->
-    do_start_scenario(testing_scenario, test_helpers:regular_vars()),
-    NumOfUsers = 10,
-    amoc_controller:add_users(1, NumOfUsers),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, NumOfUsers, NumOfUsers),
-    Ret = amoc_controller:remove_users(999, true),
-    ?assertMatch({ok, 10}, Ret),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, 0, NumOfUsers).
+    start_and_remove_some_users(10, 999, 10, 0).
 
 killing_many_users_in_a_big_test_is_correct(_) ->
-    do_start_scenario(testing_scenario, test_helpers:regular_vars()),
-    NumOfUsers = 200,
-    amoc_controller:add_users(1, NumOfUsers),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, NumOfUsers, NumOfUsers),
-    Ret = amoc_controller:remove_users(120, true),
-    ?assertMatch({ok, 120}, Ret),
-    test_helpers:wait_until_scenario_has_users(testing_scenario, 80, NumOfUsers).
+    start_and_remove_some_users(200, 120, 120, 80).
 
 stop_non_running_scenario_fails(_) ->
     Ret = amoc_controller:stop_scenario(),
@@ -203,6 +241,26 @@ scenario_with_failing_init_fails(_) ->
     ?assertMatch({error, _}, Ret).
 
 %% helpers
+sups_with_counts() ->
+    non_empty(list(non_neg_integer())).
+
+dummy_pid() ->
+    spawn_link(fun() -> ok end).
+
+run_prop(PropName, Property, NumTests, WorkersPerScheduler) ->
+    Opts = [noshrink, {start_size, 1}, {numtests, NumTests},
+            {numworkers, WorkersPerScheduler * erlang:system_info(schedulers_online)}],
+    Res = proper:counterexample(proper:conjunction([{PropName, Property}]), Opts),
+    ?assertEqual(true, Res).
+
+start_and_remove_some_users(NumOfUsers, NumOfUsersToRemove, ExpectedRemoved, ExpectedFinal) ->
+    do_start_scenario(testing_scenario, test_helpers:regular_vars()),
+    amoc_controller:add_users(1, NumOfUsers),
+    test_helpers:wait_until_scenario_has_users(testing_scenario, NumOfUsers, NumOfUsers),
+    Ret = amoc_controller:remove_users(NumOfUsersToRemove, true),
+    ?assertMatch({ok, ExpectedRemoved}, Ret),
+    test_helpers:wait_until_scenario_has_users(testing_scenario, ExpectedFinal, NumOfUsers).
+
 do_start_scenario(Scenario) ->
     do_start_scenario(Scenario, []).