feat(member): back the overview with a keyset-paginated :overview read action

test/mv_web/member_live/index_keyset_property_test.exs

@@ -0,0 +1,86 @@
+defmodule MvWeb.MemberLive.IndexKeysetPropertyTest do
+  @moduledoc """
+  §2.2 — Keyset pagination completeness: concatenating every keyset page yields
+  exactly the full filtered set once each (no duplicates, no gaps) in a stable
+  total order.
+
+  §2.3 — Sort determinism with the unique `id` tie-breaker: members equal on the
+  sort key are ordered by `id`, and the result set equals the unsorted set.
+  """
+  use Mv.DataCase, async: false
+  use ExUnitProperties
+
+  import Mv.Fixtures, only: [member_fixture_with_actor: 2]
+
+  alias Mv.Membership.Member
+  alias MvWeb.MemberLive.Index.OverviewQuery
+
+  setup do
+    %{actor: Mv.Helpers.SystemActor.get_system_actor()}
+  end
+
+  defp clear_members(actor) do
+    Member |> Ash.read!(actor: actor) |> Enum.each(&Ash.destroy!(&1, actor: actor))
+  end
+
+  defp read_all_pages(query, actor, limit) do
+    page = Ash.read!(query, page: [limit: limit], actor: actor)
+    collect(page, page.results)
+  end
+
+  defp collect(%{more?: true} = page, acc) do
+    next = Ash.page!(page, :next)
+    collect(next, acc ++ next.results)
+  end
+
+  defp collect(_page, acc), do: acc
+
+  property "keyset pages cover the full set once, no dupes or gaps", %{actor: actor} do
+    check all(
+            n <- integer(1..12),
+            limit <- integer(1..5),
+            sort <- member_of([:last_name, :join_date, :inserted_at]),
+            order <- member_of([:asc, :desc]),
+            max_runs: 25
+          ) do
+      clear_members(actor)
+      # Deliberate ties on last_name so the tie-breaker is exercised.
+      members =
+        for i <- 1..n do
+          member_fixture_with_actor(%{last_name: "Tie#{rem(i, 3)}"}, actor)
+        end
+
+      expected = MapSet.new(members, & &1.id)
+
+      query = OverviewQuery.build(%{sort_field: sort, sort_order: order})
+      paged = read_all_pages(query, actor, limit)
+      paged_ids = Enum.map(paged, & &1.id)
+
+      assert MapSet.new(paged_ids) == expected
+      assert length(paged_ids) == MapSet.size(expected)
+    end
+  end
+
+  property "sort with ties is a deterministic total order broken by id", %{actor: actor} do
+    check all(
+            n <- integer(2..10),
+            order <- member_of([:asc, :desc]),
+            max_runs: 25
+          ) do
+      clear_members(actor)
+
+      members =
+        for _ <- 1..n do
+          member_fixture_with_actor(%{last_name: "Same"}, actor)
+        end
+
+      ordered =
+        OverviewQuery.build(%{sort_field: :last_name, sort_order: order})
+        |> Ash.read!(actor: actor)
+        |> Enum.map(& &1.id)
+
+      # All last_names equal -> order is fully determined by the id tie-breaker (asc).
+      assert ordered == Enum.sort(Enum.map(members, & &1.id))
+    end
+  end
+end