Raise on id mismatch from the cache

lib/identity_cache.rb

@@ -55,6 +55,11 @@ class << self
     mattr_accessor :fetch_read_only_records
     self.fetch_read_only_records = true
 
+    # Raise an exception if the record returned from the cache don't match the id
+    # the user expected
+    mattr_accessor :raise_on_id_mismatch
+    self.raise_on_id_mismatch = false
+
     mattr_accessor :lazy_load_associated_classes
     self.lazy_load_associated_classes = Gem::Version.new(IdentityCache::VERSION) >= Gem::Version.new("0.6")
 

lib/identity_cache/query_api.rb

@@ -1,4 +1,7 @@
 module IdentityCache
+  class CorruptedCache < StandardError
+  end
+
   module QueryAPI
     extend ActiveSupport::Concern
 
@@ -27,7 +30,9 @@ def fetch_by_id(id, options={})
             coder = IdentityCache.fetch(rails_cache_key(id)){ coder_from_record(object = resolve_cache_miss(id)) }
             object ||= record_from_coder(coder)
             if object && object.id.to_s != id.to_s
-              IdentityCache.logger.error "[IDC id mismatch] fetch_by_id_requested=#{id} fetch_by_id_got=#{object.id} for #{object.inspect[(0..100)]}"
+              message = "[IDC id mismatch] fetch_by_id_requested=#{id} fetch_by_id_got=#{object.id} for #{object.inspect[(0..100)]}"
+              IdentityCache.logger.error message
+              raise CorruptedCache.new(message) if IdentityCache.raise_on_id_mismatch
             end
             object
           end

test/fetch_test.rb

@@ -20,6 +20,15 @@ def test_fetch_with_garbage_input
     assert_nil Item.fetch_by_id('garbage')
   end
 
+  def test_fetch_with_corrupted_cache
+    attributes = @record.attributes_before_type_cast
+    attributes["id"] += 1
+    IdentityCache.cache.expects(:fetch).with(@blob_key).returns(class: @record.class.name, attributes: attributes)
+
+    IdentityCache.raise_on_id_mismatch = true
+    assert_raises(IdentityCache::CorruptedCache) { Item.fetch(1) }
+  end
+
   def test_fetch_cache_hit
     IdentityCache.cache.expects(:fetch).with(@blob_key).returns(@cached_value)