1 files changed, 59 insertions, 0 deletions
diff --git a/test/ruby/test_data.rb b/test/ruby/test_data.rb
index 4d28da6061..3cafb365ed 100644
--- a/test/ruby/test_data.rb
+++ b/test/ruby/test_data.rb
@@ -158,6 +158,65 @@ class TestData < Test::Unit::TestCase
     assert_not_operator(o1, :eql?, o3)
   end
 
+  def test_with
+    klass = Data.define(:foo, :bar)
+    source = klass.new(foo: 1, bar: 2)
+
+    # Simple
+    test = source.with
+    assert_equal(source.object_id, test.object_id)
+
+    # Changes
+    test = source.with(foo: 10)
+
+    assert_equal(1, source.foo)
+    assert_equal(2, source.bar)
+    assert_equal(source, klass.new(foo: 1, bar: 2))
+
+    assert_equal(10, test.foo)
+    assert_equal(2, test.bar)
+    assert_equal(test, klass.new(foo: 10, bar: 2))
+
+    test = source.with(foo: 10, bar: 20)
+
+    assert_equal(1, source.foo)
+    assert_equal(2, source.bar)
+    assert_equal(source, klass.new(foo: 1, bar: 2))
+
+    assert_equal(10, test.foo)
+    assert_equal(20, test.bar)
+    assert_equal(test, klass.new(foo: 10, bar: 20))
+
+    # Keyword splat
+    changes = { foo: 10, bar: 20 }
+    test = source.with(**changes)
+
+    assert_equal(1, source.foo)
+    assert_equal(2, source.bar)
+    assert_equal(source, klass.new(foo: 1, bar: 2))
+
+    assert_equal(10, test.foo)
+    assert_equal(20, test.bar)
+    assert_equal(test, klass.new(foo: 10, bar: 20))
+
+    # Wrong protocol
+    assert_raise_with_message(ArgumentError, "wrong number of arguments (given 1, expected 0)") do
+      source.with(10)
+    end
+    assert_raise_with_message(ArgumentError, "unknown keywords: :baz, :quux") do
+      source.with(foo: 1, bar: 2, baz: 3, quux: 4)
+    end
+    assert_raise_with_message(ArgumentError, "wrong number of arguments (given 1, expected 0)") do
+      source.with(1, bar: 2)
+    end
+    assert_raise_with_message(ArgumentError, "wrong number of arguments (given 2, expected 0)") do
+      source.with(1, 2)
+    end
+    assert_raise_with_message(ArgumentError, "wrong number of arguments (given 1, expected 0)") do
+      source.with({ bar: 2 })
+    end
+  end
+
   def test_memberless
     klass = Data.define