1 files changed, 59 insertions, 0 deletions
diff --git a/activesupport/test/core_ext/object/deep_dup_test.rb b/activesupport/test/core_ext/object/deep_dup_test.rb
new file mode 100644
index 0000000000..1fb26ebac7
--- /dev/null
+++ b/activesupport/test/core_ext/object/deep_dup_test.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+require "abstract_unit"
+require "active_support/core_ext/object"
+
+class DeepDupTest < ActiveSupport::TestCase
+  def test_array_deep_dup
+    array = [1, [2, 3]]
+    dup = array.deep_dup
+    dup[1][2] = 4
+    assert_nil array[1][2]
+    assert_equal 4, dup[1][2]
+  end
+
+  def test_hash_deep_dup
+    hash = { a: { b: "b" } }
+    dup = hash.deep_dup
+    dup[:a][:c] = "c"
+    assert_nil hash[:a][:c]
+    assert_equal "c", dup[:a][:c]
+  end
+
+  def test_array_deep_dup_with_hash_inside
+    array = [1, { a: 2, b: 3 } ]
+    dup = array.deep_dup
+    dup[1][:c] = 4
+    assert_nil array[1][:c]
+    assert_equal 4, dup[1][:c]
+  end
+
+  def test_hash_deep_dup_with_array_inside
+    hash = { a: [1, 2] }
+    dup = hash.deep_dup
+    dup[:a][2] = "c"
+    assert_nil hash[:a][2]
+    assert_equal "c", dup[:a][2]
+  end
+
+  def test_deep_dup_initialize
+    zero_hash = Hash.new 0
+    hash = { a: zero_hash }
+    dup = hash.deep_dup
+    assert_equal 0, dup[:a][44]
+  end
+
+  def test_object_deep_dup
+    object = Object.new
+    dup = object.deep_dup
+    dup.instance_variable_set(:@a, 1)
+    assert_not object.instance_variable_defined?(:@a)
+    assert dup.instance_variable_defined?(:@a)
+  end
+
+  def test_deep_dup_with_hash_class_key
+    hash = { Integer => 1 }
+    dup = hash.deep_dup
+    assert_equal 1, dup.keys.length
+  end
+end