I'd like to do something like this:
some_method.should_raise <any kind of exception, I don't care>
How should I do this?
some_method.should_raise exception
... doesn't work.
expect { some_method }.to raise_error
RSpec 1 Syntax:
lambda { some_method }.should raise_error
See the documentation (for RSpec 1 syntax) and RSpec 2 documentation for more.
RSpec 2
expect { some_method }.to raise_error
expect { some_method }.to raise_error(SomeError)
expect { some_method }.to raise_error("oops")
expect { some_method }.to raise_error(/oops/)
expect { some_method }.to raise_error(SomeError, "oops")
expect { some_method }.to raise_error(SomeError, /oops/)
expect { some_method }.to raise_error(...){|e| expect(e.data).to eq "oops" }
# Rspec also offers to_not:
expect { some_method }.to_not raise_error
...
Note: raise_error
and raise_exception
are interchangeable.
RSpec 1
lambda { some_method }.should raise_error
lambda { some_method }.should raise_error(SomeError)
lambda { some_method }.should raise_error(SomeError, "oops")
lambda { some_method }.should raise_error(SomeError, /oops/)
lambda { some_method }.should raise_error(...){|e| e.data.should == "oops" }
# Rspec also offers should_not:
lambda { some_method }.should_not raise_error
...
Note: raise_error
is an alias for raise_exception
.
Documentation: https://www.relishapp.com/rspec
RSpec 2:
https://www.relishapp.com/rspec/rspec-expectations/v/2-13/docs/built-in-matchers/raise-error-matcher
RSpec 1:
http://apidock.com/rspec/Spec/Matchers/raise_error
http://apidock.com/rspec/Spec/Matchers/raise_exception
Instead of lambda, use expect to:
expect { some_method }.to raise_error
This is applies for more recent versions of rspec, i.e. rspec 2.0 and up.
See the doco for more.
expect
is better or worse than lambda
.
expect { visit welcome_path }.to raise_error
The syntax changed recently and now it is:
expect { ... }.to raise_error(ErrorClass)
From version 3.3 on rspec-expections
gem raises a warning for a blank raise_error without a parameter
expect { raise StandardError }.to raise_error # results in warning
expect { raise StandardError }.to raise_error(StandardError) # fine
This gives you a hint that your code may fail with a different error than the test intended to check.
WARNING: Using the raise_error matcher without providing a specific error or message risks false positives, since raise_error will match when Ruby raises a NoMethodError, NameError or ArgumentError, potentially allowing the expectation to pass without even executing the method you are intending to call. Instead consider providing a specific error class or message. This message can be supressed by setting: RSpec::Expectations.configuration.warn_about_potential_false_positives = false.
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