Our matcher is quite useful, but we could make it neater. Would you like to learn how to build sustainable Rails apps and ship more often? Do not handle them all in one. You can find more information on defining fluent, chained matchers, diffable matchers and accepting blocks as arguments in the RSpec documentation. Accepting a string in our match block — rather than a response object — helps keep our matcher generic enough that we can re-use it later. It all boils down to coming up with a true or false response to indicate whether the test passed or failed. Matchers can be written as plain old Ruby objects, as long as they conform to a specific API — methods named like the blocks in our previous example.
Define a custom matcher rspec-expectations provides a DSL for defining custom matchers. We can therefore create a new file. Which is not as nice as with our DSL -version. We want to assert that sensitive information is omitted from the JSON document for unauthorised users. Test code is code like any other code, which needs to be maintained.
Learn more and download a free copy. You might argue that this matcher is not quite high-level enough to actually model our domain.
Browse documentation Keyword search. We could write the above matcher as a class as follows:.
This helps you build a suite of easily re-usable matchers that the entire team can use. ArgumentError – writinh, but there might be edge cases where you want to pass the exception to the user.
These are often useful for expressing expectations in the domain of your application. Do not handle them all in one.
It therefore needs to be well-factored and use the rxpec language. Defining Custom Matchers in RSpec Defining custom RSpec matchers is really easy and a great way to increase the readability of your tests.
define matcher – Custom matchers – RSpec Expectations – RSpec – Relish
Take care to handle exceptions appropriately in your matcher, e. It therefore needs to be readable and DRY. To get into this habit, try to limit yourself to a maximum of three lines per test: Next post Previous post. It is probably a good idea to tighten up that if statement with an elsif for Rack:: RSpec dumps the actual and expected values, and combines them with the name of our matcher to create a generic error message.
First comes the expected value, second the actual one.
Soon you’ll be able to also add collaborators here! Our matcher is quite useful, but we could make it neater.
Define a custom matcher
There are two ways to implement matchers: You might argue that this matcher is not quite high-level enough to actually model our domain. The specs are fair enough, but there are two different levels of abstraction in play here: Our matcher is quite useful, but we could make it neater. RSpec dumps the actual and expected values and combines them with the name of our matcher to create a generic error message. We want to assert that sensitive information is omitted from the JSON document for unauthorised users.
Extending our custom matcher further Our custom matcher does the job but there are some potential problems with it.
This gave us the opportunity to use the much terser ternary operator and split out the fetching of the status code from the matcher comparison. You should handle each StandardError with care!
We define our own domain-specific assertions and use them to compose readable specifications. Home Feed About Archives github twitter. We can improve our matcher further with a custom exception message. Our matcher is basically ready for use, but we can do matcjers.
– Defining Custom Matchers in RSpec
We want to assert that sensitive information is omitted from the XML for unauthorised users. Behind the scenes RSpec:: Note that we can change the block argument names to match our domain.
This example uses RSpec 3. Test code is code like any other code, which needs to be maintained.