1 files changed, 18 insertions, 0 deletions
diff --git a/activerecord/test/cases/cache_key_test.rb b/activerecord/test/cases/cache_key_test.rb
new file mode 100644
index 0000000000..e52bbd3d30
--- /dev/null
+++ b/activerecord/test/cases/cache_key_test.rb
@@ -0,0 +1,18 @@
+require "cases/helper"
+require "models/invoice"
+require "models/line_item"
+
+class CacheKeyTest < ActiveRecord::TestCase
+  def setup
+    @invoice = Invoice.create
+    LineItem.create(invoice: @invoice)
+    @invoice.reload
+  end
+
+  def test_cache_key_changes_when_child_touched
+    key = @invoice.cache_key
+    @invoice.line_items[0].touch
+    @invoice.reload
+    assert_not_equal key, @invoice.cache_key
+  end
+end