Add Statistics module for member and cycle aggregates

- first_join_year, active/inactive counts, joins/exits by year
- cycle_totals_by_year, open_amount_total
- Unit tests for Statistics

test/mv/statistics_test.exs

@@ -0,0 +1,190 @@
+defmodule Mv.StatisticsTest do
+  @moduledoc """
+  Tests for Mv.Statistics module (member and membership fee cycle statistics).
+  """
+  use Mv.DataCase, async: true
+
+  require Ash.Query
+  import Ash.Expr
+
+  alias Mv.Statistics
+  alias Mv.MembershipFees
+  alias Mv.MembershipFees.MembershipFeeCycle
+  alias Mv.MembershipFees.MembershipFeeType
+
+  setup do
+    actor = Mv.Helpers.SystemActor.get_system_actor()
+    %{actor: actor}
+  end
+
+  defp create_fee_type(actor, attrs \\ %{}) do
+    MembershipFeeType
+    |> Ash.Changeset.for_create(
+      :create,
+      Map.merge(
+        %{
+          name: "Test Fee #{System.unique_integer([:positive])}",
+          amount: Decimal.new("50.00"),
+          interval: :yearly
+        },
+        attrs
+      )
+    )
+    |> Ash.create!(actor: actor)
+  end
+
+  describe "first_join_year/1" do
+    test "returns the year of the earliest join_date", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2019-03-15]})
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2022-01-01]})
+      assert Statistics.first_join_year(actor: actor) == 2019
+    end
+
+    test "returns the only member's join year when one member exists", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2021-06-01]})
+      assert Statistics.first_join_year(actor: actor) == 2021
+    end
+
+    test "returns nil when no members exist", %{actor: actor} do
+      # Relies on empty member table for this test; may be nil if other tests created members
+      result = Statistics.first_join_year(actor: actor)
+      assert result == nil or is_integer(result)
+    end
+  end
+
+  describe "active_member_count/1" do
+    test "returns 0 when there are no members", %{actor: actor} do
+      assert Statistics.active_member_count(actor: actor) == 0
+    end
+
+    test "returns 1 when one member has no exit_date", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-01-15]})
+      assert Statistics.active_member_count(actor: actor) == 1
+    end
+
+    test "returns 0 for that member when exit_date is set", %{actor: actor} do
+      _member =
+        Mv.Fixtures.member_fixture(%{join_date: ~D[2023-01-15], exit_date: ~D[2024-06-01]})
+
+      assert Statistics.active_member_count(actor: actor) == 0
+    end
+
+    test "counts only active members when mix of active and inactive", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2022-01-01]})
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-01-01], exit_date: ~D[2024-01-01]})
+      assert Statistics.active_member_count(actor: actor) == 1
+    end
+  end
+
+  describe "inactive_member_count/1" do
+    test "returns 0 when all members are active", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-01-01]})
+      assert Statistics.inactive_member_count(actor: actor) == 0
+    end
+
+    test "returns 1 when one member has exit_date set", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2022-01-01], exit_date: ~D[2024-06-01]})
+      assert Statistics.inactive_member_count(actor: actor) == 1
+    end
+  end
+
+  describe "joins_by_year/2" do
+    test "returns 0 for year with no joins", %{actor: actor} do
+      assert Statistics.joins_by_year(1999, actor: actor) == 0
+    end
+
+    test "returns 1 when one member has join_date in that year", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-06-15]})
+      assert Statistics.joins_by_year(2023, actor: actor) == 1
+    end
+
+    test "returns 2 when two members joined in that year", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-01-01]})
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2023-12-31]})
+      assert Statistics.joins_by_year(2023, actor: actor) == 2
+    end
+  end
+
+  describe "exits_by_year/2" do
+    test "returns 0 for year with no exits", %{actor: actor} do
+      assert Statistics.exits_by_year(1999, actor: actor) == 0
+    end
+
+    test "returns 1 when one member has exit_date in that year", %{actor: actor} do
+      Mv.Fixtures.member_fixture(%{join_date: ~D[2020-01-01], exit_date: ~D[2023-06-15]})
+      assert Statistics.exits_by_year(2023, actor: actor) == 1
+    end
+  end
+
+  describe "cycle_totals_by_year/2" do
+    test "returns zero totals for year with no cycles", %{actor: actor} do
+      result = Statistics.cycle_totals_by_year(1999, actor: actor)
+      assert result.total == Decimal.new(0)
+      assert result.paid == Decimal.new(0)
+      assert result.unpaid == Decimal.new(0)
+      assert result.suspended == Decimal.new(0)
+    end
+
+    test "returns totals by status for cycles in that year", %{actor: actor} do
+      fee_type = create_fee_type(actor, %{amount: Decimal.new("50.00")})
+
+      # Creating members with fee type triggers cycle generation (2020..today). We use 2024 cycles.
+      _member1 =
+        Mv.Fixtures.member_fixture(%{
+          join_date: ~D[2020-01-01],
+          membership_fee_type_id: fee_type.id
+        })
+
+      _member2 =
+        Mv.Fixtures.member_fixture(%{
+          join_date: ~D[2020-01-01],
+          membership_fee_type_id: fee_type.id
+        })
+
+      # Get 2024 cycles and set status (each member has one 2024 yearly cycle from generator)
+      cycles_2024 =
+        MembershipFeeCycle
+        |> Ash.Query.filter(
+          expr(cycle_start >= ^~D[2024-01-01] and cycle_start < ^~D[2025-01-01])
+        )
+        |> Ash.read!(actor: actor)
+        |> Enum.sort_by(& &1.member_id)
+
+      [c1, c2] = cycles_2024
+      assert {:ok, _} = Ash.update(c1, %{status: :paid}, domain: MembershipFees, actor: actor)
+
+      assert {:ok, _} =
+               Ash.update(c2, %{status: :suspended}, domain: MembershipFees, actor: actor)
+
+      result = Statistics.cycle_totals_by_year(2024, actor: actor)
+      assert Decimal.equal?(result.total, Decimal.new("100.00"))
+      assert Decimal.equal?(result.paid, Decimal.new("50.00"))
+      assert Decimal.equal?(result.unpaid, Decimal.new(0))
+      assert Decimal.equal?(result.suspended, Decimal.new("50.00"))
+    end
+  end
+
+  describe "open_amount_total/1" do
+    test "returns 0 when there are no unpaid cycles", %{actor: actor} do
+      assert Statistics.open_amount_total(actor: actor) == Decimal.new(0)
+    end
+
+    test "returns sum of amount for all unpaid cycles", %{actor: actor} do
+      fee_type = create_fee_type(actor, %{amount: Decimal.new("50.00")})
+
+      _member =
+        Mv.Fixtures.member_fixture(%{
+          join_date: ~D[2020-01-01],
+          membership_fee_type_id: fee_type.id
+        })
+
+      # Cycle generator creates yearly cycles (2020..today), all unpaid by default
+      unpaid_sum = Statistics.open_amount_total(actor: actor)
+      assert Decimal.compare(unpaid_sum, Decimal.new(0)) == :gt
+      # Should be 50 * number of years from 2020 to current year
+      current_year = Date.utc_today().year
+      expected_count = current_year - 2020 + 1
+      assert Decimal.equal?(unpaid_sum, Decimal.new(50 * expected_count))
+    end
+  end
+end