Helpful test assertions for MiniTest suite in Rails

test_assertions.rb

# Some very helpful asserts to add on top of MiniTest, includes ordered array
# and set comparison, ActiveRecord attribute validation, and layout assertions
# This was originally written by @madrobby for Freckle: https://letsfreckle.com

module MiniTest
  module Assertions
    def assert_layout(layout, message=nil)
      assert_equal "layouts/#{layout}", @response.layout, message
    end

    def assert_equal_list(expected, actual, message=nil)
      if expected == actual
        assert expected == actual
      else
        if (expected-actual).empty?
          assert expected == actual, message ||
            "Lists have the same items, but not in the same order.\n\n#{diff(expected,actual)}"
        else
          assert_equal_set expected, actual
        end
      end
    end

    # to_a converts hashes into arrays for comparison
    def assert_equal_set(expected, actual, message=nil)
      assert (expected.to_a-actual.to_a).empty? && (actual.to_a-expected.to_a).empty?, message ||
        "Sets don't have the same items.\n\nMissing in actual:\n #{(expected.to_a-actual.to_a).inspect}\n\nExtra set items:\n #{(actual.to_a-expected.to_a).inspect}"
    end

    def assert_valid_attribute(object, attribute, value)
      message = "Unexpected errors on #{attribute.inspect} with value `#{value.inspect}' after validation"
      object.send("#{attribute}=", value)
      object.valid?
      if object.errors[attribute].kind_of? Array
        assert object.errors[attribute].empty?, message
      else
        assert object.errors.on(attribute).nil?, message
      end
    end

    def assert_invalid_attribute(object, attribute, value)
      message = "Expected errors on #{attribute.inspect} with value `#{value.inspect}' after validation"
      object.send("#{attribute}=", value)
      object.valid?
      if object.errors[attribute].kind_of? Array
        assert !object.errors[attribute].empty?, message
      else
        assert !object.errors.on(attribute).nil?, message
      end
    end

    def assert_valid(record)
      assert record.valid?, "Expected record to be valid, but it is not: #{record.errors.full_messages.join("\n")}"
    end

    def assert_not_valid(record)
      assert !record.valid?, 'Expected record to be not valid, but it is.'
    end

    def assert_valid_with(record, attribute, value)
      current_value = record.send(attribute)
      record.send("#{attribute.to_s}=", value)
      if record.valid?
        assert true
      else
        errors = record.errors.on(attribute)
        assert errors.nil? || errors.empty?, "Expected #{value.inspect} to be valid for attribute #{attribute}: #{record.errors.full_messages.join("\n")}"
      end
      record.send("#{attribute.to_s}=", current_value)
    end

    def assert_not_valid_with(record, attribute, value)
      current_value = record.send(attribute)
      record.send("#{attribute.to_s}=", value)
      record.valid?
      assert !record.errors.nil? && !record.errors.empty? &&
        !record.errors.on(attribute).nil? && !record.errors.on(attribute).empty?,
        "Expected #{value.inspect} to be not valid for attribute #{attribute}, but it is."
      record.send("#{attribute.to_s}=", current_value)
    end
  end
end