Add NEWS.md entry for ENV.fetch_values and that tests

From ruby/rubygems#8501

Co-authored-by: Suleyman Musayev <96992680+msuliq@users.noreply.github.com>

Author: hsbt

NEWS.md

@@ -11,6 +11,12 @@ Note that each entry is kept to a minimum, see links for details.
 
 Note: We're only listing outstanding class updates.
 
+* ENV
+
+    * `ENV.fetch_values` is added. It returns an array of values for the
+      given names, raising `KeyError` for missing names unless a block is
+      given. [[Feature #21781]]
+
 * Kernel
 
     * `Kernel#autoload_relative` and `Module#autoload_relative` are added.

test/ruby/test_env.rb

@@ -281,6 +281,26 @@ def test_values_at
     assert_equal(["foo", "foo"], ENV.values_at("test", "test"))
   end
 
+  def test_fetch_values
+    ENV["test"] = "foo"
+    ENV["test2"] = "bar"
+    assert_equal(["foo", "bar"], ENV.fetch_values("test", "test2"))
+    assert_equal(["foo", "foo"], ENV.fetch_values("test", "test"))
+    assert_equal([], ENV.fetch_values)
+
+    ENV.delete("test2")
+    assert_raise(KeyError) { ENV.fetch_values("test", "test2") }
+
+    assert_equal(["foo", "default"], ENV.fetch_values("test", "test2") { "default" })
+    assert_equal(["foo", "TEST2"], ENV.fetch_values("test", "test2") { |k| k.upcase })
+
+    e = assert_raise(KeyError) { ENV.fetch_values("test2") }
+    assert_same(ENV, e.receiver)
+    assert_equal("test2", e.key)
+
+    assert_invalid_env {|v| ENV.fetch_values(v)}
+  end
+
   def test_select
     ENV["test"] = "foo"
     h = ENV.select {|k| IGNORE_CASE ? k.upcase == "TEST" : k == "test" }