Fix validation callbacks on multiple context

I found a bug that validation callbacks don't fire on multiple context.
So I've fixed it.

Example:

```ruby
class Dog
  include ActiveModel::Validations
  include ActiveModel::Validations::Callbacks

  attr_accessor :history

  def initialize
    @history = []
  end

  before_validation :set_before_validation_on_a, on: :a
  before_validation :set_before_validation_on_b, on: :b
  after_validation :set_after_validation_on_a, on: :a
  after_validation :set_after_validation_on_b, on: :b

  def set_before_validation_on_a; history << "before_validation on a"; end
  def set_before_validation_on_b; history << "before_validation on b"; end
  def set_after_validation_on_a;  history << "after_validation on a" ; end
  def set_after_validation_on_b;  history << "after_validation on b" ; end
end
```

Before:

```
d = Dog.new
d.valid?([:a, :b])
d.history # []
```

After:

```
d = Dog.new
d.valid?([:a, :b])
d.history # ["before_validation on a", "before_validation on b", "after_validation on a", "after_validation on b"]
```

1 files changed, 13 insertions, 9 deletions

diff --git a/activemodel/lib/active_model/validations/callbacks.rb b/activemodel/lib/active_model/validations/callbacks.rb
index 4d0ab2a2fe..11a8b2b229 100644
--- a/activemodel/lib/active_model/validations/callbacks.rb
+++ b/activemodel/lib/active_model/validations/callbacks.rb
@@ -54,14 +54,16 @@ module ActiveModel
         #   person.valid? # => true
         #   person.name   # => "bob"
         def before_validation(*args, &block)
-          options = args.last
-          if options.is_a?(Hash) && options[:on]
-            options[:if] = Array(options[:if])
-            options[:on] = Array(options[:on])
+          options = args.extract_options!
+          options[:if] = Array(options[:if])
+
+          if options.key?(:on)
             options[:if].unshift ->(o) {
-              options[:on].include? o.validation_context
+              !(Array(options[:on]) & Array(o.validation_context)).empty?
             }
           end
+
+          args << options
           set_callback(:validation, :before, *args, &block)
         end
 
@@ -95,13 +97,15 @@ module ActiveModel
           options = args.extract_options!
           options[:prepend] = true
           options[:if] = Array(options[:if])
-          if options[:on]
-            options[:on] = Array(options[:on])
+
+          if options.key?(:on)
             options[:if].unshift ->(o) {
-              options[:on].include? o.validation_context
+              !(Array(options[:on]) & Array(o.validation_context)).empty?
             }
           end
-          set_callback(:validation, :after, *(args << options), &block)
+
+          args << options
+          set_callback(:validation, :after, *args, &block)
         end
       end