Add test coverage for category hierarchy and account search

Model-level:
- Category::GroupTest (new): for() grouping and the new select_options
  helper (order + indent labels).
- CategoryTest: alphabetically_by_hierarchy scope ordering.
- Rule::ConditionFilter::TransactionCategoryTest (new)
- Rule::ActionExecutor::SetTransactionCategoryTest (new)
- Import::CategoryMappingTest (new): grouping + 'Add as new category'
  still prepends correctly.

Controller/integration-level (asserting actual rendered HTML order):
- SplitsControllerTest: category combobox data-value ordering.
- Transactions::CategorizesControllerTest: bulk-categorize <select>
  option ordering.
- TransactionsControllerTest:
  - search filter checkbox ordering (q[categories][])
  - new-transaction DS::Select category ordering (via trigger id +
    ancestor traversal)
  - new-transaction account select renders a search box

All new/modified test files verified with 'ruby -c' (syntax) and
cross-checked fixture names, family scoping, route helpers, and field
names against the actual fixtures/routes/views. Ruby/Bundler network
access to rubygems.org is unavailable in this sandbox, so the suite
itself has not been executed — run 'bin/rails test' before merging.

test/models/category/group_test.rb

@@ -0,0 +1,52 @@
+require "test_helper"
+
+class Category::GroupTest < ActiveSupport::TestCase
+  setup do
+    @family = families(:dylan_family)
+  end
+
+  test "for groups categories by parent, root categories without children get an empty subcategories array" do
+    groups = Category::Group.for(@family.categories)
+
+    food_group = groups.find { |g| g.category == categories(:food_and_drink) }
+    assert_equal [ categories(:subcategory) ], food_group.subcategories
+
+    income_group = groups.find { |g| g.category == categories(:income) }
+    assert_equal [], income_group.subcategories
+  end
+
+  test "for does not include a category as its own root when it is a subcategory" do
+    groups = Category::Group.for(@family.categories)
+
+    assert_nil groups.find { |g| g.category == categories(:subcategory) }
+  end
+
+  test "select_options orders parent immediately followed by its children" do
+    options = Category::Group.select_options(@family.categories)
+
+    parent_index = options.index { |label, id| id == categories(:food_and_drink).id }
+    child_index = options.index { |label, id| id == categories(:subcategory).id }
+
+    assert_not_nil parent_index
+    assert_not_nil child_index
+    assert_equal parent_index + 1, child_index, "subcategory should immediately follow its parent in the options list"
+  end
+
+  test "select_options indents subcategory labels so they're visually distinguishable from parents" do
+    options = Category::Group.select_options(@family.categories)
+
+    parent_label, = options.find { |label, id| id == categories(:food_and_drink).id }
+    child_label, = options.find { |label, id| id == categories(:subcategory).id }
+
+    assert_equal categories(:food_and_drink).name, parent_label
+    assert_not_equal categories(:subcategory).name, child_label
+    assert_includes child_label, categories(:subcategory).name
+  end
+
+  test "select_options returns [label, id] pairs usable directly by options_for_select / form.select" do
+    options = Category::Group.select_options(@family.categories)
+
+    assert options.all? { |pair| pair.is_a?(Array) && pair.size == 2 }
+    assert options.all? { |_label, id| id.present? }
+  end
+end

test/models/category_test.rb

@@ -159,4 +159,15 @@ class CategoryTest < ActiveSupport::TestCase
     assert lookup.key?(category.id)
     assert_not lookup.key?(0)
   end
+
+  test "alphabetically_by_hierarchy orders a category's subcategories immediately after it" do
+    ordered = @family.categories.alphabetically_by_hierarchy.to_a
+
+    parent_index = ordered.index(categories(:food_and_drink))
+    child_index = ordered.index(categories(:subcategory))
+
+    assert_not_nil parent_index
+    assert_not_nil child_index
+    assert_equal parent_index + 1, child_index
+  end
 end

test/models/import/category_mapping_test.rb

@@ -0,0 +1,25 @@
+require "test_helper"
+
+class Import::CategoryMappingTest < ActiveSupport::TestCase
+  setup do
+    @mapping = import_mappings(:one)
+  end
+
+  test "selectable_values groups subcategories immediately after their parent" do
+    options = @mapping.selectable_values
+
+    parent_index = options.index { |_label, id| id == categories(:food_and_drink).id }
+    child_index = options.index { |_label, id| id == categories(:subcategory).id }
+
+    assert_not_nil parent_index
+    assert_not_nil child_index
+    assert_equal parent_index + 1, child_index
+  end
+
+  test "selectable_values still prepends 'Add as new category' when key is present" do
+    options = @mapping.selectable_values
+
+    assert_equal "Add as new category", options.first.first
+    assert_equal Import::Mapping::CREATE_NEW_KEY, options.first.last
+  end
+end

test/models/rule/action_executor/set_transaction_category_test.rb

@@ -0,0 +1,19 @@
+require "test_helper"
+
+class Rule::ActionExecutor::SetTransactionCategoryTest < ActiveSupport::TestCase
+  setup do
+    @rule = rules(:one)
+    @executor = Rule::ActionExecutor::SetTransactionCategory.new(@rule)
+  end
+
+  test "options groups subcategories immediately after their parent" do
+    options = @executor.options
+
+    parent_index = options.index { |_label, id| id == categories(:food_and_drink).id }
+    child_index = options.index { |_label, id| id == categories(:subcategory).id }
+
+    assert_not_nil parent_index
+    assert_not_nil child_index
+    assert_equal parent_index + 1, child_index
+  end
+end

test/models/rule/condition_filter/transaction_category_test.rb

@@ -0,0 +1,28 @@
+require "test_helper"
+
+class Rule::ConditionFilter::TransactionCategoryTest < ActiveSupport::TestCase
+  setup do
+    @rule = rules(:one)
+    @filter = Rule::ConditionFilter::TransactionCategory.new(@rule)
+  end
+
+  test "options groups subcategories immediately after their parent" do
+    options = @filter.options
+
+    parent_index = options.index { |_label, id| id == categories(:food_and_drink).id }
+    child_index = options.index { |_label, id| id == categories(:subcategory).id }
+
+    assert_not_nil parent_index
+    assert_not_nil child_index
+    assert_equal parent_index + 1, child_index
+  end
+
+  test "options indents subcategory labels" do
+    options = @filter.options
+
+    child_label, = options.find { |_label, id| id == categories(:subcategory).id }
+
+    assert_not_equal categories(:subcategory).name, child_label
+    assert_includes child_label, categories(:subcategory).name
+  end
+end