Use assert_respond_to because it has better error messaging

The patch is ok Neeraj but please do this on the rails top dir:
$ grep -r 'assert ' * | grep respond_to and change all the uses

i get all this files waiting for your change ...

actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:new_any_old_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:createany_old_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:deliverany_old_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:create_Any_old_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:deliver_Any_old_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:create_1_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:deliver_1_template)
actionmailer/test/old_base/mail_service_test.rb: assert !RespondToMailer.respond_to?(:foo_deliver_template)
actionmailer/test/base_test.rb: assert !BaseMailer.respond_to?(:mail)
actionmailer/test/base_test.rb: assert !BaseMailer.respond_to?(:headers)
actionpack/test/controller/url_for_test.rb: assert controller.respond_to?(:home_url)
actionpack/test/controller/url_for_test.rb: assert controller.respond_to?(:home_url)
actionpack/test/abstract/collector_test.rb: assert !collector.respond_to?(:unknown)
actionpack/test/abstract/collector_test.rb: assert !collector.respond_to?(:js)
activemodel/test/cases/callbacks_test.rb: assert !ModelCallbacks.respond_to?(:before_initialize)
activemodel/test/cases/callbacks_test.rb: assert !ModelCallbacks.respond_to?(:around_initialize)
activemodel/test/cases/attribute_methods_test.rb: assert !ModelWithAttributes.new.respond_to?(:foo)
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:to_key), "The model should respond to to_key"
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:to_param), "The model should respond to to_param"
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:valid?), "The model should respond to valid?"
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:persisted?), "The model should respond to persisted?"
activemodel/lib/active_model/lint.rb: assert model.class.respond_to?(:model_name), "The model should respond to model_name"
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:errors), "The model should respond to errors"
activemodel/lib/active_model/lint.rb: assert model.respond_to?(:errors), "The model should respond to errors"
activemodel/lib/active_model/lint.rb: assert @model.respond_to?(:to_model), "The object should respond_to to_model"
activerecord/test/cases/finder_test.rb: #assert !topic.respond_to?("title")
activerecord/test/cases/finder_test.rb: assert topic.respond_to?("author_name")
activerecord/test/cases/named_scope_test.rb: assert Topic.approved.respond_to?(:limit)
activerecord/test/cases/named_scope_test.rb: assert Topic.approved.respond_to?(:count)
activerecord/test/cases/named_scope_test.rb: assert Topic.approved.respond_to?(:length)
activerecord/test/cases/named_scope_test.rb: assert !Topic.approved.respond_to?(:with_create_scope)
activerecord/test/cases/named_scope_test.rb: assert Topic.approved.respond_to?(:with_create_scope, true)
activerecord/test/cases/named_scope_test.rb: assert Topic.respond_to?(reserved_method, true)
activerecord/test/cases/relations_test.rb: assert relation.respond_to?(method), "Topic.scoped should respond to #{method.inspect}"
activerecord/test/cases/relations_test.rb: assert ! relation.respond_to?(:matching_attributes)
activerecord/test/cases/relations_test.rb: assert relation.respond_to?(:matching_attributes, true)
activerecord/test/cases/relations_test.rb: assert relation.respond_to?(method), "Topic.scoped should respond to #{method.inspect}"
activerecord/test/cases/relations_test.rb: assert DeveloperOrderedBySalary.scoped.respond_to?(:all_ordered_by_name)
activerecord/test/cases/relations_test.rb: assert Topic.scoped.respond_to?(:by_lifo)
activerecord/test/cases/autosave_association_test.rb: assert !@pirate.respond_to?(:validate_associated_records_for_non_validated_ship)
activerecord/test/cases/autosave_association_test.rb: assert !@pirate.respond_to?(:validate_associated_records_for_non_validated_parrot)
activerecord/test/cases/autosave_association_test.rb: assert !@pirate.respond_to?(:validate_associated_records_for_non_validated_parrots)
activerecord/test/cases/base_test.rb: assert !topic.respond_to?("nothingness")
activerecord/test/cases/base_test.rb: assert !topic.respond_to?(:nothingness)
activerecord/test/cases/base_test.rb: assert !topic.respond_to?("mumbo")
activerecord/test/cases/base_test.rb: assert !Task.new.respond_to?("#{method}=")
activerecord/test/cases/xml_serialization_test.rb: assert !authors(:david).hello_posts.first.respond_to?(:label)
activerecord/test/cases/associations/has_many_associations_test.rb: assert !client_association.respond_to?(:private_method)
activerecord/test/cases/associations/has_many_associations_test.rb: assert client_association.respond_to?(:private_method, true)
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("name")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("name=")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("name?")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("joined_on")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: #assert project.respond_to?("joined_on=")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("joined_on?")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("access_level")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: #assert project.respond_to?("access_level=")
activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb: assert project.respond_to?("access_level?")
activerecord/test/cases/attribute_methods_test.rb: assert topic.respond_to?('title')
activerecord/test/cases/attribute_methods_test.rb: assert !topic.respond_to?('title_hello_world')
activerecord/test/cases/attribute_methods_test.rb: assert topic.respond_to?(meth)
activerecord/test/cases/attribute_methods_test.rb: assert topic.respond_to?(meth)
activerecord/test/cases/attribute_methods_test.rb: assert topic.respond_to?(meth)
activerecord/test/cases/attribute_methods_test.rb: assert !topic.respond_to?(:title)
activerecord/test/cases/attribute_methods_test.rb: assert !topic.respond_to?(:title=)
activerecord/test/cases/attribute_methods_test.rb: assert !topic.respond_to?(:title?)
activerecord/test/cases/json_serialization_test.rb: assert !@david.posts.first.respond_to?(:favorite_quote)
activerecord/test/cases/finder_respond_to_test.rb: assert !Topic.respond_to?(:find_by_undertitle)
activerecord/test/cases/finder_respond_to_test.rb: assert !Topic.respond_to?(:fail_to_find_by_title)
activerecord/test/cases/finder_respond_to_test.rb: assert !Topic.respond_to?(:find_by_title?)
activerecord/test/cases/finder_respond_to_test.rb: assert !Topic.respond_to?(:fail_to_find_or_create_by_title)
activerecord/test/cases/finder_respond_to_test.rb: assert !Topic.respond_to?(:find_or_create_by_title?)
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(col.to_s), "should respond to the schema's string key, but failed on: #{col.to_s}"
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(col.to_sym), "should respond to the schema's symbol key, but failed on: #{col.to_sym}"
activeresource/test/cases/base/schema_test.rb: assert Person.respond_to?(:schema), "should at least respond to the schema method"
activeresource/test/cases/base/schema_test.rb: assert s.respond_to?(:attrs), "should return attributes in theory"
activeresource/test/cases/base/schema_test.rb: assert !self.respond_to?(bad_value), "should only respond to a known attribute type, but accepted: #{bad_value.inspect}"
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(new_attr_name), "should respond to the attribute in a passed-in schema, but failed on: #{new_attr_name}"
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(new_attr_name_two), "should respond to the attribute from the schema, but failed on: #{new_attr_name_two}"
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(new_attr_name), "should respond to the attribute in a passed-in schema, but failed on: #{new_attr_name}"
activeresource/test/cases/base/schema_test.rb: assert Person.new.respond_to?(new_attr_name_two), "should respond to the attribute from the schema, but failed on: #{new_attr_name_two}"
activeresource/test/cases/base_test.rb: assert matz.respond_to?(:name)
activeresource/test/cases/base_test.rb: assert matz.respond_to?(:name=)
activeresource/test/cases/base_test.rb: assert matz.respond_to?(:name?)
activeresource/test/cases/base_test.rb: assert !matz.respond_to?(:super_scalable_stuff)
activesupport/test/core_ext/object_and_class_ext_test.rb: assert !@string.respond_to?(method)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert @class.respond_to?(:foo)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert @class.respond_to?(:foo=)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert @object.respond_to?(:bar)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert !@object.respond_to?(:bar=)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert @class.respond_to?(:shaq)
activesupport/test/core_ext/class/attribute_accessor_test.rb: assert !@object.respond_to?(:shaq)
activesupport/test/core_ext/class/class_inheritable_attributes_test.rb: assert !@klass.new.respond_to?(:a=)
activesupport/test/core_ext/class/class_inheritable_attributes_test.rb: assert !@klass.new.respond_to?(:a=)
activesupport/test/core_ext/class/class_inheritable_attributes_test.rb: assert !@klass.new.respond_to?(:a=)
activesupport/test/core_ext/class/class_inheritable_attributes_test.rb: assert !@klass.new.respond_to?(:a=)
activesupport/test/core_ext/class/delegating_attributes_test.rb: assert single_class.respond_to?(:both)
activesupport/test/core_ext/class/delegating_attributes_test.rb: assert single_class.respond_to?(:both=)
activesupport/test/core_ext/class/delegating_attributes_test.rb: assert single_class.respond_to?(:no_instance_reader)
activesupport/test/core_ext/class/delegating_attributes_test.rb: assert single_class.respond_to?(:no_instance_reader=)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(:bar)
activesupport/test/core_ext/module_test.rb: assert !@instance.respond_to?(method)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(method)
activesupport/test/core_ext/module_test.rb: assert !@instance.respond_to?(:quux_with_baz!)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(:quux_with_baz!)
activesupport/test/core_ext/module_test.rb: assert !@instance.respond_to?(:quux_with_baz!)
activesupport/test/core_ext/module_test.rb: assert !@instance.respond_to?(:quux_with_baz?)
activesupport/test/core_ext/module_test.rb: assert !@instance.respond_to?(:quux_with_baz=)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(:quux_with_baz!)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(:quux_with_baz?)
activesupport/test/core_ext/module_test.rb: assert @instance.respond_to?(:quux_with_baz=)
activesupport/test/core_ext/module/synchronization_test.rb: assert @instance.respond_to?(:value_with_synchronization)
activesupport/test/core_ext/module/synchronization_test.rb: assert @instance.respond_to?(:value_without_synchronization)
activesupport/test/core_ext/module/synchronization_test.rb: assert @target.respond_to?(:to_s_without_synchronization)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert @module.respond_to?(:foo)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert @module.respond_to?(:foo=)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert @object.respond_to?(:bar)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert !@object.respond_to?(:bar=)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert @module.respond_to?(:shaq)
activesupport/test/core_ext/module/attribute_accessor_test.rb: assert !@object.respond_to?(:shaq)
activesupport/test/core_ext/string_ext_test.rb: assert UNICODE_STRING.respond_to?(:mb_chars)
activesupport/test/dependencies_test.rb: assert !Module.new.respond_to?(:const_missing_without_dependencies)
activesupport/test/dependencies_test.rb: assert !Module.new.respond_to?(:load_without_new_constant_marking)
activesupport/test/multibyte_chars_test.rb: assert ''.mb_chars.respond_to?(:slice) # Defined on Chars
activesupport/test/multibyte_chars_test.rb: assert ''.mb_chars.respond_to?(:capitalize!) # Defined on Chars
activesupport/test/multibyte_chars_test.rb: assert ''.mb_chars.respond_to?(:gsub) # Defined on String
activesupport/test/multibyte_chars_test.rb: assert !''.mb_chars.respond_to?(:undefined_method) # Not defined
activesupport/test/time_zone_test.rb: assert zone.tzinfo.respond_to?(:period_for_local)
railties/test/railties/engine_test.rb: assert !Rails::Engine.respond_to?(:config)
railties/test/railties/plugin_test.rb: assert !Rails::Plugin.respond_to?(:config)
railties/test/railties/railtie_test.rb: assert !Rails::Railtie.respond_to?(:config)
railties/test/application/console_test.rb: assert User.new.respond_to?(:name)
railties/test/application/console_test.rb: assert !User.new.respond_to?(:age)
railties/test/application/console_test.rb: assert !User.new.respond_to?(:age)
railties/test/application/console_test.rb: assert User.new.respond_to?(:age)