WRITING CUSTOM RSPEC MATCHERS

There are two ways to implement matchers: Custom RSpec matchers can help with this problem. You might argue that this matcher is not quite high-level enough to actually model our domain. We could write such a test as follows:. Home Feed About Archives github twitter. We want to assert that sensitive information is omitted from the JSON document for unauthorised users. Note that we can change the block argument names to match our domain.

More about adding a collaborator. ArgumentError – occures, but there might be edge cases where you want to pass the exception to the user. We want to assert that sensitive information is omitted from the JSON document for unauthorised users. To get into this habit, try to limit yourself to a maximum of three lines per test: Close To add a collaborator to this project you will need to use the Relish gem to add the collaborator via a terminal command. I believe you should start writing custom matchers as soon as possible in a project.

For anything non-trivial, it is nice to just deal with plain Ruby. It all boils down to coming up with a true or false response to indicate whether the test passed or failed. The specs are fair enough, but there are two different levels of abstraction in play here: Perhaps you are using more than one HTTP framework in your tests or – more likely – you are using the Rack:: Defining custom RSpec matchers is really easy and a great way to increase the readability of your tests.

writing custom rspec matchers

It therefore needs to be readable and DRY. We can introduce a helper method to make things pretty again:.

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How to Use Custom RSpec Matchers to Specify Behaviour

It all boils down to coming up with a true or false response to indicate whether the test passed or failed. We can improve our matcher further with a custom exception message. Home Feed About Archives github twitter. These are often useful for expressing expectations in the domain of your application. We want to assert that sensitive information is omitted from the XML for unauthorised users.

Matchers can be written as plain old Ruby objects, as long as they conform to a specific API — methods named like the blocks in customm previous example.

Our matcher is basically ready for use, but we can do better. This would be a fair point, and whenever this particular itch comes up, you could scratch it not with a more specific matcher, but with another helper method around your generic matcher:.

Writing Custom RSpec Matchers – Timothy’s Blog

This gave us the opportunity to use the much terser ternary operator and split out the fetching of the status code from matchres matcher comparison.

XML str end end. If you need to write a more complex matcher and would like to use the Class -approach yourself, writng head over to our API -documentation and read the docs about the MatcherProtocol. Define a custom matcher rspec-expectations provides a DSL for defining custom matchers.

Writing Custom RSpec Matchers

RSpec dumps the actual and expected values, and combines them with the name of our matcher to create a generic error message. Note that we can change the block argument names to match our domain. ArgumentError – occures, but there might be edge cases where you want to pass the exception to the user.

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Defining Custom Matchers in RSpec Defining custom RSpec matchers is really easy and a great way to increase the readability of your tests. Close To add a collaborator to this project you will need to use the Rsped gem to add the collaborator via a terminal command.

Custom RSpec matchers can help with this problem. Next post Previous post. This example uses RSpec 3.

writing custom rspec matchers

Make sure your matcher returns either true or false. If you want your matcher to be readable in different matchefs, you can use the. We can therefore create a new file. First comes the expected value, second the actual one. We could write the above matcher as a class as follows:.

Our matcher is quite useful, but we could make it neater. Providing a custom error message We can improve our matcher further with a custom exception message.

You might argue that this matcher is not quite high-level enough to actually model our domain. This matcher is also just a Ruby class, for which you could write tests if you wanted to go really meta.