From d5b57c890e2d0d7e42d726fb5a16a0ab30da67ea Mon Sep 17 00:00:00 2001
From: Graham Turner <turnertgraham@gmail.com>
Date: Thu, 27 Sep 2018 14:58:29 -0400
Subject: Array with single item correctly uses cache_key

---
 activesupport/lib/active_support/cache.rb          |  2 +-
 .../test/cache/behaviors/cache_store_behavior.rb   | 49 ++++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

(limited to 'activesupport')

diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 222ef2b515..2be79d86dd 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -647,7 +647,7 @@ module ActiveSupport
             if key.size > 1
               key = key.collect { |element| expanded_key(element) }
             else
-              key = key.first
+              key = expanded_key(key.first)
             end
           when Hash
             key = key.sort_by { |k, _| k.to_s }.collect { |k, v| "#{k}=#{v}" }
diff --git a/activesupport/test/cache/behaviors/cache_store_behavior.rb b/activesupport/test/cache/behaviors/cache_store_behavior.rb
index 30735eb0eb..9f54b1e7de 100644
--- a/activesupport/test/cache/behaviors/cache_store_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_store_behavior.rb
@@ -290,6 +290,55 @@ module CacheStoreBehavior
     assert_equal "bar", @cache.read("fu/foo")
   end
 
+  InstanceTest = Struct.new(:name, :id) do
+    def cache_key
+      "#{name}/#{id}"
+    end
+
+    def to_param
+      "hello"
+    end
+  end
+
+  def test_array_with_single_instance_as_cache_key_uses_cache_key_method
+    test_instance_one = InstanceTest.new("test", 1)
+    test_instance_two = InstanceTest.new("test", 2)
+
+    @cache.write([test_instance_one], "one")
+    @cache.write([test_instance_two], "two")
+
+    assert_equal "one", @cache.read([test_instance_one])
+    assert_equal "two", @cache.read([test_instance_two])
+  end
+
+  def test_array_with_multiple_instances_as_cache_key_uses_cache_key_method
+    test_instance_one = InstanceTest.new("test", 1)
+    test_instance_two = InstanceTest.new("test", 2)
+    test_instance_three = InstanceTest.new("test", 3)
+
+    @cache.write([test_instance_one, test_instance_three], "one")
+    @cache.write([test_instance_two, test_instance_three], "two")
+
+    assert_equal "one", @cache.read([test_instance_one, test_instance_three])
+    assert_equal "two", @cache.read([test_instance_two, test_instance_three])
+  end
+
+  def test_format_of_expanded_key_for_single_instance
+    test_instance_one = InstanceTest.new("test", 1)
+
+    expanded_key = @cache.send(:expanded_key, test_instance_one)
+
+    assert_equal expanded_key, test_instance_one.cache_key
+  end
+
+  def test_format_of_expanded_key_for_single_instance_in_array
+    test_instance_one = InstanceTest.new("test", 1)
+
+    expanded_key = @cache.send(:expanded_key, [test_instance_one])
+
+    assert_equal expanded_key, test_instance_one.cache_key
+  end
+
   def test_hash_as_cache_key
     @cache.write({ foo: 1, fu: 2 }, "bar")
     assert_equal "bar", @cache.read("foo=1/fu=2")
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