From 8c4d6a04f896be4a2ace6046098de71a0ac41ec2 Mon Sep 17 00:00:00 2001
From: George Claghorn <george@basecamp.com>
Date: Tue, 31 Mar 2020 17:39:02 -0400
Subject: [PATCH] Redis cache store: fix expanding empty keys with no namespace

---
 activesupport/lib/active_support/cache/redis_cache_store.rb | 4 ++--
 activesupport/test/cache/behaviors/cache_store_behavior.rb  | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/activesupport/lib/active_support/cache/redis_cache_store.rb b/activesupport/lib/active_support/cache/redis_cache_store.rb
index 58ccdc6043..a5b1e370c2 100644
--- a/activesupport/lib/active_support/cache/redis_cache_store.rb
+++ b/activesupport/lib/active_support/cache/redis_cache_store.rb
@@ -444,11 +444,11 @@ module ActiveSupport
 
         # Truncate keys that exceed 1kB.
         def normalize_key(key, options)
-          truncate_key super.b
+          truncate_key super&.b
         end
 
         def truncate_key(key)
-          if key.bytesize > max_key_bytesize
+          if key && key.bytesize > max_key_bytesize
             suffix = ":sha2:#{::Digest::SHA2.hexdigest(key)}"
             truncate_at = max_key_bytesize - suffix.bytesize
             "#{key.byteslice(0, truncate_at)}#{suffix}"
diff --git a/activesupport/test/cache/behaviors/cache_store_behavior.rb b/activesupport/test/cache/behaviors/cache_store_behavior.rb
index 07b1d28324..9f40b0cc34 100644
--- a/activesupport/test/cache/behaviors/cache_store_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_store_behavior.rb
@@ -110,6 +110,12 @@ module CacheStoreBehavior
     end
   end
 
+  def test_read_multi_with_empty_keys_and_a_logger_and_no_namespace
+    @cache.options[:namespace] = nil
+    @cache.logger = ActiveSupport::Logger.new(nil)
+    assert_equal({}, @cache.read_multi)
+  end
+
   def test_fetch_multi
     @cache.write("foo", "bar")
     @cache.write("fud", "biz")