rspec: model.should be_valid

April 18, 2007 code 2 min read

One of the things I always check when spec’ing is that the model that I just created is valid.

@mymodel.should be_valid

This uses RSpec’s predicate support (any call to be_something? calls something? on the target object), and returns a correct but very unhelpful error:

expected valid? to return true, got false

Here is a little rspec matcher that I threw together this morning to check if a model is valid and spit out the validation errors:

module Spec
  module Rails
    module Matchers
      class BeValid  #:nodoc:

        def matches?(model)
          @model = model

        def failure_message
          "#{@model.class} expected to be valid but had errors:\n  #{@model.errors.full_messages.join("\n  ")}"

        def negative_failure_message
          "#{@model.class} expected to have errors, but it did not"

        def description
          "be valid"


      def be_valid

Now, I get:

MyModel expected to be valid but had errors:
  Password confirmation can't be blank
  Email has already been taken

This is nothing fancy, but it’s the small stuff that make life meaningful, so I thought I would share it. Throw the matcher code above into your spec_helper and check if your models are valid.

update: added negative_failure_message so “model.should_not be_valid” will work

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avatar of Brandon Keepers I am Brandon Keepers, and I work at GitHub on making Open Source more approachable, effective, and ubiquitous. I tend to think like an engineer, work like an artist, dream like an astronaut, love like a human, and sleep like a baby.