Delegate exists? to proxy for all types (#47)

* Delegate `exists?` to proxy for all types

* Explicitly add exists proxy and add tests

Author: ayushn21

lib/kredis/types/counter.rb

@@ -1,5 +1,5 @@
 class Kredis::Types::Counter < Kredis::Types::Proxying
-  proxying :multi, :set, :incrby, :decrby, :get, :del
+  proxying :multi, :set, :incrby, :decrby, :get, :del, :exists?
 
   attr_accessor :expires_in
 

lib/kredis/types/enum.rb

@@ -1,7 +1,7 @@
 require "active_support/core_ext/object/inclusion"
 
 class Kredis::Types::Enum < Kredis::Types::Proxying
-  proxying :set, :get, :del
+  proxying :set, :get, :del, :exists?
 
   attr_accessor :values, :default
 

lib/kredis/types/hash.rb

@@ -1,7 +1,7 @@
 require "active_support/core_ext/hash"
 
 class Kredis::Types::Hash < Kredis::Types::Proxying
-  proxying :hget, :hset, :hmget, :hdel, :hgetall, :hkeys, :hvals, :del
+  proxying :hget, :hset, :hmget, :hdel, :hgetall, :hkeys, :hvals, :del, :exists?
 
   attr_accessor :typed
 

lib/kredis/types/list.rb

@@ -1,5 +1,5 @@
 class Kredis::Types::List < Kredis::Types::Proxying
-  proxying :lrange, :lrem, :lpush, :rpush
+  proxying :lrange, :lrem, :lpush, :rpush, :exists?
 
   attr_accessor :typed
 

lib/kredis/types/set.rb

@@ -1,5 +1,5 @@
 class Kredis::Types::Set < Kredis::Types::Proxying
-  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop
+  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop, :exists?
 
   attr_accessor :typed
 

lib/kredis/types/slots.rb

@@ -1,7 +1,7 @@
 class Kredis::Types::Slots < Kredis::Types::Proxying
   class NotAvailable < StandardError; end
 
-  proxying :incr, :decr, :get, :del
+  proxying :incr, :decr, :get, :del, :exists?
 
   attr_accessor :available
 

lib/kredis/types/unique_list.rb

@@ -1,6 +1,6 @@
 # You'd normally call this a set, but Redis already has another data type for that
 class Kredis::Types::UniqueList < Kredis::Types::List
-  proxying :multi, :ltrim
+  proxying :multi, :ltrim, :exists?
 
   attr_accessor :typed, :limit
 

test/types/counter_test.rb

@@ -63,4 +63,11 @@ class CounterTest < ActiveSupport::TestCase
     stub_redis_down(@counter) { @counter.increment }
     assert_equal 0, @counter.value
   end
+
+  test "exists?" do
+    assert_not @counter.exists?
+
+    @counter.increment
+    assert @counter.exists?
+  end
 end

test/types/enum_test.rb

@@ -30,4 +30,11 @@ class EnumTest < ActiveSupport::TestCase
     @enum.reset
     assert @enum.one?
   end
+
+  test "exists?" do
+    assert_not @enum.exists?
+
+    @enum.value = "one"
+    assert @enum.exists?
+  end
 end

test/types/hash_test.rb

@@ -76,4 +76,11 @@ class HashTest < ActiveSupport::TestCase
     @hash.remove
     assert_equal({}, @hash.to_h)
   end
+
+  test "exists?" do
+    assert_not @hash.exists?
+
+    @hash[:key]  = :value
+    assert @hash.exists?
+  end
 end