test(vereinfacht): add tests and scope README

- Config, Client, SyncContact, Vereinfacht module tests (no real API)
- vereinfacht_test_README: document test scope

test/mv/vereinfacht/changes/sync_contact_test.exs

@@ -0,0 +1,92 @@
+defmodule Mv.Vereinfacht.Changes.SyncContactTest do
+  @moduledoc """
+  Tests for Mv.Vereinfacht.Changes.SyncContact.
+
+  When Vereinfacht is not configured, member create/update should succeed
+  and vereinfacht_contact_id remains nil.
+  """
+  use Mv.DataCase, async: false
+
+  alias Mv.Membership
+
+  setup do
+    clear_vereinfacht_env()
+    :ok
+  end
+
+  describe "member create when Vereinfacht not configured" do
+    test "member is created and vereinfacht_contact_id is nil" do
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      attrs = %{
+        first_name: "Sync",
+        last_name: "Test",
+        email: "sync_test_#{System.unique_integer([:positive])}@example.com"
+      }
+
+      assert {:ok, member} = Membership.create_member(attrs, actor: system_actor)
+      assert member.vereinfacht_contact_id == nil
+    end
+  end
+
+  describe "member update when Vereinfacht not configured" do
+    test "member is updated and vereinfacht_contact_id is unchanged" do
+      member = Mv.Fixtures.member_fixture()
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      assert {:ok, updated} =
+               Membership.update_member(member, %{first_name: "Updated"}, actor: system_actor)
+
+      assert updated.vereinfacht_contact_id == nil
+    end
+  end
+
+  describe "when Vereinfacht is configured" do
+    # Regression: after_transaction callback receives 2 args (changeset, result), not 3.
+    # If the callback had arity 3, create_member would raise BadArityError.
+    # Also: Client must send JSON-encoded body (iodata); raw map causes ArgumentError
+    # when the request is sent. With an unreachable URL we get :econnrefused before
+    # that, so this test would not catch the iodata bug; a Bypass/stub server would.
+    test "create_member succeeds and after_transaction runs without error (API may fail)" do
+      set_vereinfacht_env()
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      attrs = %{
+        first_name: "API",
+        last_name: "Test",
+        email: "api_test_#{System.unique_integer([:positive])}@example.com"
+      }
+
+      assert {:ok, member} = Membership.create_member(attrs, actor: system_actor)
+      assert member.id
+      # Sync may fail (e.g. connection refused), so contact_id can stay nil
+    after
+      clear_vereinfacht_env()
+    end
+
+    test "update_member succeeds and after_transaction runs without error (API may fail)" do
+      set_vereinfacht_env()
+      member = Mv.Fixtures.member_fixture()
+      system_actor = Mv.Helpers.SystemActor.get_system_actor()
+
+      assert {:ok, updated} =
+               Membership.update_member(member, %{first_name: "Updated"}, actor: system_actor)
+
+      assert updated.id == member.id
+    after
+      clear_vereinfacht_env()
+    end
+  end
+
+  defp set_vereinfacht_env do
+    System.put_env("VEREINFACHT_API_URL", "http://127.0.0.1:1/api/v1")
+    System.put_env("VEREINFACHT_API_KEY", "test-key")
+    System.put_env("VEREINFACHT_CLUB_ID", "2")
+  end
+
+  defp clear_vereinfacht_env do
+    System.delete_env("VEREINFACHT_API_URL")
+    System.delete_env("VEREINFACHT_API_KEY")
+    System.delete_env("VEREINFACHT_CLUB_ID")
+  end
+end