Support for unified Integer class in Ruby 2.4+

Ruby 2.4 unifies Fixnum and Bignum into Integer: https://bugs.ruby-lang.org/issues/12005

* Forward compat with new unified Integer class in Ruby 2.4+.
* Backward compat with separate Fixnum/Bignum in Ruby 2.2 & 2.3.
* Drops needless Fixnum distinction in docs, preferring Integer.

1 files changed, 3 insertions, 2 deletions

diff --git a/activejob/lib/active_job/arguments.rb b/activejob/lib/active_job/arguments.rb
index 33bd5b4eb3..a5c749e5e7 100644
--- a/activejob/lib/active_job/arguments.rb
+++ b/activejob/lib/active_job/arguments.rb
@@ -24,7 +24,7 @@ module ActiveJob
   end
 
   # Raised when an unsupported argument type is set as a job argument. We
-  # currently support NilClass, Fixnum, Float, String, TrueClass, FalseClass,
+  # currently support NilClass, Integer, Fixnum, Float, String, TrueClass, FalseClass,
   # Bignum, BigDecimal, and objects that can be represented as GlobalIDs (ex: Active Record).
   # Raised if you set the key for a Hash something else than a string or
   # a symbol. Also raised when trying to serialize an object which can't be
@@ -34,7 +34,8 @@ module ActiveJob
   module Arguments
     extend self
     # :nodoc:
-    TYPE_WHITELIST = [ NilClass, Fixnum, Float, String, TrueClass, FalseClass, Bignum, BigDecimal ]
+    # Calls #uniq since Integer, Fixnum, and Bignum are all the same class on Ruby 2.4+
+    TYPE_WHITELIST = [ NilClass, String, Integer, Fixnum, Bignum, Float, BigDecimal, TrueClass, FalseClass ].uniq
 
     # Serializes a set of arguments. Whitelisted types are returned
     # as-is. Arrays/Hashes are serialized element by element.