Here’s a little snippet that I use to quickly form tests to ensure that my models validation is working correctly from within unit tests:

  # In test_helper.rb
  # Give this function an array of invalid values, an array of valid values, the object and
  # attribute name to test, and it will ensure that only valid values are allowed
  def validation_tester ( valid_values, invalid_values, attribute_name, test_object )
    valid_values.each do |val|
      test_object.[]=(attribute_name, val)
      assert test_object.save, "#{attribute_name} should be valid: #{test_object.[](attribute_name)}"
      assert test_object.valid?
      assert !test_object.errors.invalid?(attribute_name)
    end

    invalid_values.each do |val|
      test_object.[]=(attribute_name, val)
      assert !test_object.save, "#{attribute_name} should NOT be valid: #{val}"
      assert !test_object.valid?
      assert test_object.errors.invalid?(attribute_name)
    end
  end

Then, use it as follows in your unit tests:

  def test_email_validation
    valid_emails = ['matt@test.com', 'matt.hall@test.com', 'matt@test.ing.com', 'matt.hall@test.ing.com']
    invalid_emails = ['@test.com', 'test.com', 'matt@', 'matt.hall@com', '.matt@test.ing.co.uk', 'matt@@test.com', '', '.@.']

    u = create_user
    validation_tester( valid_emails, invalid_emails, 'email', u)
  end

Can anyone suggest any improvements?

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