How do you simulate a missing I18n key in an Rspec test? I have a helper that looks to use a I18n key if its available. I don't know how to create the test case for when it is not available. Based on console testing I'm pretty sure the helper method is correct, but I don't know how to construct the test against that outcome (when all three possible title types are not set).
# app/helpers/application_helper.rb def available_page_title title = "" case when content_for?(:page_title) title = content_for(:page_title) when !@page_title.nil? title = @page_title when I18n.exists?('page_title.default') title = t('page_title.default') end end --
# config/locales/en.yml en: page_title: delimiter: ' - ' default: Default Page Title admin_namespace: 'Admin' # spec/helpers/application_helper.rb describe 'available_page_title' do it '(1) returns the the translation title if no other titles set' do allow(I18n).to receive(:t).with('page_title.default').and_return("Test Title from i18n") @page_title = nil expect(helper.available_page_title).to eq(t('page_title.default')) end it '(2) returns the the @page_title if it exists and no content_for exists' do allow(I18n).to receive(:t).with('page_title.default').and_return("Test Title from i18n") translation_title = t('page_title.default') @page_title = "Test Title from @page_title" expect(helper.available_page_title).to eq(@page_title) end it '(3) returns the the content_for title if it exists' do allow(I18n).to receive(:t).with('page_title.default').and_return("Test Title from i18n") translation_title = t('page_title.default') @page_title = "Test Title from @page_title" helper.content_for(:page_title, 'Test Title from content_for') expect(helper.available_page_title).to eq('Test Title from content_for') end it '(4) returns a blank string if no titles are found' do # Things I've tried... # I18n.backend.store_translations(:en, { page_title: { default: '' }}) # I18n.backend.store_translations(:en) # I18n.backend.store_translations(:en, { nil }) # I18n.backend.store_translations() # I18n.backend = I18n::Backend::Simple.new allow(I18n).to receive(:t).with('page_title.default').and_return(nil) @page_title = nil expect(helper.available_page_title).to eq('') end end Here's the test results:
$ bundle exec rspec spec/helpers/application_helper_spec.rb:130 Run options: include {:locations=>{"./spec/helpers/application_helper_spec.rb"=>[130]}} Randomized with seed 14478 ApplicationHelper available_page_title (3) returns the the content_for title if it exists (1) returns the the translation title if no other titles set (2) returns the the @page_title if it exists and no content_for exists (4) returns a blank string if no titles are found (FAILED - 1) Failures: 1) ApplicationHelper available_page_title should (4) return a blank string if no titles are found Failure/Error: expect(helper.available_page_title).to eq('') expected: "" got: "Default Page Title" (compared using ==) # ./spec/helpers/application_helper_spec.rb:160:in `block (3 levels) in <top (required)>' Finished in 0.69197 seconds (files took 4.32 seconds to load) 4 examples, 1 failure Failed examples: rspec ./spec/helpers/application_helper_spec.rb:152 # ApplicationHelper available_page_title should (4) return a blank string if no titles are found Randomized with seed 14478 Update 2017-05-31
@gwcodes's answer helped a little but still didn't get the test set up properly.
allow(I18n).to receive(:translate).with('page_title.default').and_return(nil) Using that line, the test is set up so that there actually is still a key page_title.default, but its value is nil. That's not useful.
What my helper method checks for is the existence of the key. Here's the pry output of the current test situation:
[5] pry(#<RSpec::ExampleGroups::ApplicationHelper::AvailablePageTitle>)> I18n.translate('page_title.default') => nil [6] pry(#<RSpec::ExampleGroups::ApplicationHelper::AvailablePageTitle>)> I18n.exists?('page_title.default') => true [7] pry(#<RSpec::ExampleGroups::ApplicationHelper::AvailablePageTitle>)> I18n.t('page_title.default').empty? => false So the question still remains. How do you set the test environment so that a check for the existence of an I18n key returns false?
2 Answers
Answers 1
I did come up with a solution by stubbing an I18n Backend for testing (although it does seem a little like the ball peen hammer approach).
I created spec/support/i18n_simple_stub.rb:
module I18n module Backend class SimpleStub def exists?(key, *args) false end end end end and then set the backend in that (previously failing) test. Here's the new test:
it '(4) returns a blank string if no titles are found' do # Sets exists? method to false I18n.backend = I18n::Backend::SimpleStub.new @page_title = nil expect(helper.available_page_title).to eq('') end If anyone has a better method, I'd love to hear it and learn.
Answers 2
I am thinking to use your first solution into a shared context.
# spec/support/i18n_stubs.rb RSpec.shared_context 'i18n stubs' do def stub_i18n_value_with_nil(key) allow(I18n).to receive(:t).with(key).and_return(nil) allow(I18n).to receive(:exists?).with(key).and_return(false) end end Then add require support/i18n_stubs on your spec helper file. Inside wherever your spec file needs it, you can just simply put include_context 'i18n stubs' and call stub_i18n_value_with_nil('some.i18n.key') before doing assertions.
For example in spec file:
require 'spec_helper' RSpec.describe 'some_file_or_class' do include_context 'i18n stubs' describe 'available_page_title' do context 'when i18n key is not present' do before(:each) do stub_i18n_value_with_nil('some.i18n.key') end it 'returns blank string' do # do assertion here end end end end 
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