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Project: RSpec Mocks 2.6

Method stubs

Stub return values

obj.stub(:message).and_return('this is the value to return')
obj.stub(:message) { 'this is the value to return' }

These two forms are somewhat interchangeable. The difference is that the
argument to and_return is evaluated immediately, whereas the block contents
are evaluated lazily when the obj receives the message message.

The block format is generally preferred as it is more terse and more consistent
with other forms described below, but lazy evaluation can be confusing because
things aren't evaluated in the order in which they are declared.

Fake implementation

obj.stub(:message) do |arg1, arg2|
  # set expectations about the args in this block
  # and/or set a return value


obj.stub(:message).and_raise("this error")

You can also use the block format, for consistency with other stubs:

obj.stub(:message) { raise "this error" }
obj.stub(:message) { throw :this_symbol }

Argument constraints

Explicit arguments

obj.stub(:message).with('an argument') { ... }
obj.stub(:message).with('more_than', 'one_argument') { ... }

Argument matchers

obj.stub(:message).with(anything()) { ... }
obj.stub(:message).with(an_instance_of(Money)) { ... }
obj.stub(:message).with(hash_including(:a => 'b')) { ... }

Regular expressions

obj.stub(:message).with(/abc/) { ... }


  1. stub with a simple return value
  2. stub with substitute implementation
  3. stub a chain of methods
  4. stub on any instance of a class
  5. as_null_object
  6. double handling to_ary

Last published over 7 years ago by .