Add UnboundMethod#original_name and UnboundMethod#bind_call types

This patch adds missing RBS for `UnboundMethod#original_name` and `UnboundMethod#bind_call`. And it also adds test for UnboundMethod class.

core/unbound_method.rbs

@@ -150,4 +150,20 @@ class UnboundMethod
   # if there is no method on superclass.
   #
   def super_method: () -> UnboundMethod?
+
+  # Returns the original name of the method.
+  #
+  #     class C
+  #       def foo; end
+  #       alias bar foo
+  #     end
+  #     C.instance_method(:bar).original_name # => :foo
+  #
+  def original_name: () -> Symbol
+
+  # Bind *umeth* to *recv* and then invokes the method with the specified
+  # arguments. This is semantically equivalent to `umeth.bind(recv).call(args,
+  # ...)`.
+  #
+  def bind_call: (untyped recv, *untyped args) ?{ (*untyped) -> untyped } -> untyped
 end

test/stdlib/UnboundMethod_test.rb

@@ -1,10 +1,75 @@
 require_relative "test_helper"
 
-class UnboundMethodTest < StdlibTest
-  target UnboundMethod
+class UnboundMethodTest < Test::Unit::TestCase
+  include TypeAssertions
+  testing "::UnboundMethod"
+
+  class TestClass
+    def m(a, m = 1, *rest, x, k: 1, **kwrest, &blk)
+    end
+
+    # to_s has super method
+    def to_s
+      ''
+    end
+  end
+
+  def test_arity
+    assert_send_type "() -> Integer",
+                     unbound_method, :arity
+  end
+
+  def test_bind
+    assert_send_type "(Object) -> Method",
+                     unbound_method, :bind, 42
+  end
+
+  def test_name
+    assert_send_type "() -> Symbol",
+                     unbound_method, :name
+  end
+
+  def test_owner
+    assert_send_type "() -> Module",
+                     unbound_method, :owner
+  end
 
   def test_parameters
-    42.method(:to_s).unbind.parameters
-    method(:test_parameters).unbind.parameters
+    assert_send_type "() -> Array[[ Symbol ]]",
+                     unbound_method, :parameters
+    assert_send_type "() -> Array[[ Symbol, Symbol ]]",
+                     TestClass.instance_method(:m), :parameters
+  end
+
+  def test_source_location
+    assert_send_type "() -> nil",
+                     unbound_method, :source_location
+    assert_send_type "() -> [ String, Integer ]",
+                     TestClass.instance_method(:m), :source_location
+  end
+
+  def test_super_method
+    assert_send_type "() -> nil",
+                     TestClass.instance_method(:m), :super_method
+    assert_send_type "() -> UnboundMethod",
+                     TestClass.instance_method(:to_s), :super_method
+  end
+
+  def test_original_name
+    assert_send_type "() -> Symbol",
+                     unbound_method, :original_name
+  end
+
+  def test_bind_call
+    assert_send_type "(Integer) -> String",
+                     unbound_method, :bind_call, 42
+    assert_send_type "(Integer, Integer) -> String",
+                     unbound_method, :bind_call, 42, 16
+    assert_send_type "(UnboundMethodTest::TestClass, Integer, Integer, foo: String) { () -> void } -> nil",
+                     TestClass.instance_method(:m), :bind_call, TestClass.new, 42, 43, foo: 'bar' do end
+  end
+
+  def unbound_method
+    Integer.instance_method(:to_s)
   end
 end