3 files changed, 48 insertions, 16 deletions
diff --git a/activesupport/test/core_ext/array/extract_test.rb b/activesupport/test/core_ext/array/extract_test.rb
new file mode 100644
index 0000000000..f26e055033
--- /dev/null
+++ b/activesupport/test/core_ext/array/extract_test.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "active_support/core_ext/array"
+
+class ExtractTest < ActiveSupport::TestCase
+  def test_extract
+    numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+    array_id = numbers.object_id
+
+    odd_numbers = numbers.extract!(&:odd?)
+
+    assert_equal [1, 3, 5, 7, 9], odd_numbers
+    assert_equal [0, 2, 4, 6, 8], numbers
+    assert_equal array_id, numbers.object_id
+  end
+
+  def test_extract_without_block
+    numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+    array_id = numbers.object_id
+
+    extract_enumerator = numbers.extract!
+
+    assert_instance_of Enumerator, extract_enumerator
+    assert_equal numbers.size, extract_enumerator.size
+
+    odd_numbers = extract_enumerator.each(&:odd?)
+
+    assert_equal [1, 3, 5, 7, 9], odd_numbers
+    assert_equal [0, 2, 4, 6, 8], numbers
+    assert_equal array_id, numbers.object_id
+  end
+
+  def test_extract_on_empty_array
+    empty_array = []
+    array_id = empty_array.object_id
+
+    new_empty_array = empty_array.extract! { }
+
+    assert_equal [], new_empty_array
+    assert_equal [], empty_array
+    assert_equal array_id, empty_array.object_id
+  end
+end
diff --git a/activesupport/test/core_ext/array/grouping_test.rb b/activesupport/test/core_ext/array/grouping_test.rb
index c182b91826..37111a5d7d 100644
--- a/activesupport/test/core_ext/array/grouping_test.rb
+++ b/activesupport/test/core_ext/array/grouping_test.rb
@@ -4,15 +4,6 @@ require "abstract_unit"
 require "active_support/core_ext/array"
 
 class GroupingTest < ActiveSupport::TestCase
-  def setup
-    # In Ruby < 2.4, test we avoid Integer#/ (redefined by mathn)
-    Fixnum.send :private, :/ unless 0.class == Integer
-  end
-
-  def teardown
-    Fixnum.send :public, :/ unless 0.class == Integer
-  end
-
   def test_in_groups_of_with_perfect_fit
     groups = []
     ("a".."i").to_a.in_groups_of(3) do |group|
diff --git a/activesupport/test/core_ext/array/prepend_append_test.rb b/activesupport/test/core_ext/array/prepend_append_test.rb
index c34acd66ad..8573dbd5a6 100644
--- a/activesupport/test/core_ext/array/prepend_append_test.rb
+++ b/activesupport/test/core_ext/array/prepend_append_test.rb
@@ -1,14 +1,11 @@
 # frozen_string_literal: true
 
 require "abstract_unit"
-require "active_support/core_ext/array"
 
 class PrependAppendTest < ActiveSupport::TestCase
-  def test_append
-    assert_equal [1, 2], [1].append(2)
-  end
-
-  def test_prepend
-    assert_equal [2, 1], [1].prepend(2)
+  def test_requiring_prepend_and_append_is_deprecated
+    assert_deprecated do
+      require "active_support/core_ext/array/prepend_and_append"
+    end
   end
 end