CSV export: robust apply_export_filters, single custom_field_ids_union, string boolean_filters, more tests

test/mv_web/controllers/member_export_controller_test.exs

@@ -187,7 +187,7 @@ defmodule MvWeb.MemberExportControllerTest do
       assert get_resp_header(conn, "content-type") |> List.first() =~ "text/csv"
       body = response(conn, 200)
       lines = export_lines(body)
-      assert length(lines) >= 1
+      assert lines != []
       assert hd(lines) =~ "First Name"
     end
 
@@ -740,7 +740,7 @@ defmodule MvWeb.MemberExportControllerTest do
       assert get_resp_header(conn, "content-type") |> List.first() =~ "text/csv"
       body = response(conn, 200)
       lines = export_lines(body)
-      assert length(lines) >= 1
+      assert lines != []
       assert hd(lines) =~ "First Name"
     end
   end