Improve redis-client error translation

Automatically handle subclasses, useful for CommandError for instance.

Author: byroot

.rubocop.yml

@@ -68,6 +68,9 @@ Style/NumericPredicate:
 Style/IfUnlessModifier:
   Enabled: false
 
+Style/MutableConstant:
+  Enabled: false # false positives
+
 Style/SignalException:
   Exclude:
     - 'lib/redis/connection/synchrony.rb'

lib/redis/client.rb

@@ -15,7 +15,7 @@ class Client < ::RedisClient
       RedisClient::WrongTypeError => Redis::WrongTypeError,
       RedisClient::ReadOnlyError => Redis::ReadOnlyError,
       RedisClient::ProtocolError => Redis::ProtocolError,
-    }.freeze
+    }
 
     class << self
       def config(**kwargs)
@@ -78,7 +78,7 @@ def password
     def call_v(command, &block)
       super(command, &block)
     rescue ::RedisClient::Error => error
-      raise ERROR_MAPPING.fetch(error.class), error.message, error.backtrace
+      translate_error!(error)
     end
 
     def blocking_call_v(timeout, command, &block)
@@ -91,19 +91,19 @@ def blocking_call_v(timeout, command, &block)
 
       super(timeout, command, &block)
     rescue ::RedisClient::Error => error
-      raise ERROR_MAPPING.fetch(error.class), error.message, error.backtrace
+      translate_error!(error)
     end
 
     def pipelined
       super
     rescue ::RedisClient::Error => error
-      raise ERROR_MAPPING.fetch(error.class), error.message, error.backtrace
+      translate_error!(error)
     end
 
     def multi
       super
     rescue ::RedisClient::Error => error
-      raise ERROR_MAPPING.fetch(error.class), error.message, error.backtrace
+      translate_error!(error)
     end
 
     def disable_reconnection(&block)
@@ -121,6 +121,21 @@ def close
 
     private
 
+    def translate_error!(error)
+      redis_error = translate_error_class(error.class)
+      raise redis_error, error.message, error.backtrace
+    end
+
+    def translate_error_class(error_class)
+      ERROR_MAPPING.fetch(error_class)
+    rescue IndexError
+      if (client_error = error_class.ancestors.find { |a| ERROR_MAPPING[a] })
+        ERROR_MAPPING[error_class] = ERROR_MAPPING[client_error]
+      else
+        raise
+      end
+    end
+
     def ensure_connected(retryable: true)
       unless @inherit_socket || (@pid ||= Process.pid) == Process.pid
         raise InheritedError,

test/redis/client_test.rb

@@ -26,6 +26,15 @@ def test_call_raise
     end
   end
 
+  def test_error_translate_subclasses
+    error = Class.new(RedisClient::CommandError)
+    assert_equal Redis::CommandError, r._client.send(:translate_error_class, error.new)
+
+    assert_raises KeyError do
+      r._client.send(:translate_error_class, StandardError.new)
+    end
+  end
+
   def test_mixed_encoding
     r.call("MSET", "fée", "\x00\xFF".b, "じ案".encode(Encoding::SHIFT_JIS), "\t".encode(Encoding::ASCII))
     assert_equal "\x00\xFF".b, r.call("GET", "fée")