Update Ractor.select

Author: soutaro

core/ractor.rbs

@@ -363,7 +363,7 @@ class Ractor
   # -->
   # TBD
   #
-  def self.select: (?) -> untyped
+  def self.select: (?) -> Array[untyped]
 
   # <!--
   #   rdoc-file=ractor.rb

test/stdlib/Ractor_test.rb

@@ -73,6 +73,18 @@ def test_recv
                      Ractor, :recv
   end
 
+  def test_select
+    rs = [
+      Ractor.new { sleep 0.1 },
+      Ractor.new { sleep 0.1 }
+    ]
+
+    assert_send_type(
+      "(::Ractor, ::Ractor) -> ::Array[untyped]",
+      Ractor, :select, *rs
+    )
+  end
+
   def test_shareable?
     assert_send_type "(untyped) -> true",
                      Ractor, :shareable?, 42