test: add orm store, model, and relation tests

test/test_orm_relation.rb

@@ -0,0 +1,56 @@
+require 'minitest/autorun'
+require 'prism'
+require 'tmpdir'
+
+class OrmRelationTest < Minitest::Test
+  def setup
+    @dir = Dir.mktmpdir('prism-relation-store')
+    @store = Prism::Orm::Store.new(File.join(@dir, 'test.pstore'))
+    @store.create_table(:items, %w[id name category])
+    item_class = Class.new(Prism::Orm::Model) do
+      table_name :items
+    end
+    item_class.store = @store
+    Object.const_set(:Item, item_class)
+  end
+
+  def teardown
+    FileUtils.remove_entry(@dir)
+    Object.send(:remove_const, :Item) if Object.const_defined?(:Item)
+  end
+
+  def test_offset_skips_leading_rows
+    %w[a b c d].each { |name| Item.create!(name: name) }
+    names = Item.order(:name).offset(2).map(&:name)
+    assert_equal %w[c d], names
+  end
+
+  def test_offset_combined_with_limit_paginates
+    %w[a b c d e].each { |name| Item.create!(name: name) }
+    page_two = Item.order(:name).offset(2).limit(2).map(&:name)
+    assert_equal %w[c d], page_two
+  end
+
+  def test_chained_where_calls_combine_with_and_semantics
+    Item.create!(name: 'match', category: 'tools')
+    Item.create!(name: 'match', category: 'other')
+    Item.create!(name: 'nope', category: 'tools')
+
+    result = Item.where(name: 'match').where(category: 'tools').to_a
+    assert_equal 1, result.size
+    assert_equal 'match', result.first.name
+  end
+
+  def test_relation_is_enumerable
+    Item.create!(name: 'b')
+    Item.create!(name: 'a')
+    assert_equal %w[a b], Item.order(:name).sort_by(&:name).map(&:name)
+    assert_equal 2, Item.all.count
+  end
+
+  def test_exists_predicate
+    refute Item.where(name: 'ghost').exists?
+    Item.create!(name: 'ghost')
+    assert Item.where(name: 'ghost').exists?
+  end
+end