stdlib: Add types for CSV::Table#each

Author: tk0miya

stdlib/csv/0/csv.rbs

@@ -3002,7 +3002,7 @@ end
 #     table['Name'] # => ["Foo", "Bar", "Baz"]
 #
 class CSV::Table[out Elem] < Object
-  include Enumerable[untyped]
+  include Enumerable[Elem]
   extend Forwardable
 
   # <!--
@@ -3633,8 +3633,8 @@ class CSV::Table[out Elem] < Object
   # Returns a new Enumerator if no block is given:
   #     table.each # => #<Enumerator: #<CSV::Table mode:col row_count:4>:each>
   #
-  def each: () -> Enumerator[untyped, self]
-          | () { (untyped) -> void } -> self
+  def each: () -> Enumerator[Elem, self]
+          | () { (Elem) -> void } -> self
           | () { (*untyped) -> void } -> self
 
   def empty?: (*untyped args) { (*untyped) -> untyped } -> untyped

test/stdlib/CSV_Table_test.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+require "csv"
+
+class CSV::TableInstanceTest < Test::Unit::TestCase
+  include TestHelper
+
+  library 'csv'
+  testing "CSV::Table[CSV::Row]"
+
+  def test_each
+    table = CSV::Table.new([
+      CSV::Row.new([], []),
+      CSV::Row.new([], []),
+      CSV::Row.new([], [])
+    ])
+
+    assert_send_type "() -> Enumerator[CSV::Row, void]",
+                     table, :each
+    assert_send_type "() { (CSV::Row) -> void } -> CSV::Table",
+                     table, :each do end
+  end
+end