Fix Kernel.rand signature

core/kernel.rbs

@@ -1318,10 +1318,10 @@ module Kernel : BasicObject
   #
   # See also Random.rand.
   #
-  def self?.rand: () -> Float
-                | (Integer arg0) -> Integer
-                | (::Range[Integer] arg0) -> Integer
-                | (::Range[Float] arg0) -> Float
+  def self?.rand: (?0) -> Float
+                | (int arg0) -> (Integer | Float)
+                | (::Range[Integer] arg0) -> Integer?
+                | (::Range[Float] arg0) -> Float?
 
   # <!--
   #   rdoc-file=io.c

lib/rbs/test.rb

@@ -22,6 +22,7 @@ module Test
     INSPECT = Kernel.instance_method(:inspect)
     METHODS = Kernel.instance_method(:methods)
     RESPOND_TOP = Kernel.instance_method(:respond_to?)
+    EQEQ = BasicObject.instance_method(:==)
 
     class ArgumentsReturn
       include Guaranteed::Inspect

lib/rbs/test/type_check.rb

@@ -327,7 +327,7 @@ def value(val, type)
         when Types::Variable
           true
         when Types::Literal
-          type.literal == val
+          Test.call(val, EQEQ, type.literal)
         when Types::Union
           type.types.any? {|type| value(val, type) }
         when Types::Intersection

sig/test.rbs

@@ -33,6 +33,9 @@ module RBS
     # Kernel#respond_to?
     RESPOND_TOP: UnboundMethod
 
+    # BasicObject#==
+    EQEQ: UnboundMethod
+
     class ArgumentsReturn
       type exit_type = :return | :exception | :break
 

test/stdlib/Kernel_test.rb

@@ -95,6 +95,19 @@ def test_autoload?
                        Kernel, :autoload?, interned
     end
   end
+
+  def test_rand
+    assert_send_type "() -> Float", Kernel, :rand
+    assert_send_type "(0) -> Float", Kernel, :rand, 0
+    assert_send_type "(_ToInt) -> Float", Kernel, :rand, 0.0
+    assert_send_type "(_ToInt) -> Float", Kernel, :rand, 0r
+    assert_send_type "(_ToInt) -> Float", Kernel, :rand, 0i
+    assert_send_type "(_ToInt) -> Integer", Kernel, :rand, 10
+    assert_send_type "(Range[Integer]) -> Integer", Kernel, :rand, 1..10
+    assert_send_type "(Range[Integer]) -> nil", Kernel, :rand, 0...0
+    assert_send_type "(Range[Float]) -> Float", Kernel, :rand, 0.0...10.0
+    assert_send_type "(Range[Float]) -> nil", Kernel, :rand, 0.0...0.0
+  end
 end
 
 class KernelTest < StdlibTest