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### Stub return values
# create a double
obj = double()
# specify a return value using `:expect` syntax
allow(obj).to receive(:message) { :value }
allow(obj).to receive(:message).and_return(:value)
# specify a return value using `:should` syntax
obj.stub(:message) { :value }
obj.stub(:message => :value)
obj.stub(:message).and_return(:value)
These forms are somewhat interchangeable. The difference is that the
block contents are evaluated lazily when the `obj` receives the
`message` message, whereas the others are evaluated as they are read.
### Fake implementation
allow(obj).to receive(:message) do |arg1, arg2|
# set expectations about the args in this block
# and/or return value
end
obj.stub(:message) do |arg1, arg2|
# set expectations about the args in this block
# and/or return a value
end
### Raising/Throwing
allow(obj).to receive(:message).and_raise("this error")
allow(obj).to receive(:message).and_throw(:this_symbol)
obj.stub(:message).and_raise("this error")
obj.stub(:message).and_throw(:this_symbol)
You can also use the block format:
allow(obj).to receive(:message) { raise "this error" }
allow(obj).to receive(:message) { throw :this_symbol }
obj.stub(:message) { raise "this error" }
obj.stub(:message) { throw :this_symbol }
### Argument constraints
#### Explicit arguments
allow(obj).to receive(:message).with('an argument') { ... }
obj.stub(:message).with('an argument') { ... }
obj.stub(:message).with('more_than', 'one_argument') { ... }
#### Argument matchers
allow(obj).to receive(:message).with(anything()) { ... }
allow(obj).to receive(:message).with(an_instance_of(Money)) { ... }
allow(obj).to receive(:message).with(hash_including(:a => 'b')) { ... }
allow(obj).to receive(:message).with(array_including(1,2,3)) { ... }
# or
allow(obj).to receive(:message).with(array_including([1,2,3])) { ... }
obj.stub(:message).with(anything()) { ... }
obj.stub(:message).with(an_instance_of(Money)) { ... }
obj.stub(:message).with(hash_including(:a => 'b')) { ... }
#### Regular expressions
allow(obj).to receive(:message).with(/abc/) { ... }
obj.stub(:message).with(/abc/) { ... }
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