Add test for u2f helper and changelog entry

changelogs/unreleased/fix-u2f-for-opera.yml

+---
+title: Fix FIDO U2F for Opera browser
+merge_request: 12082
+author: Jakub Kramarz and Jonas Kalderstam

spec/helpers/u2f_helper_spec.rb

+require 'spec_helper'
+
+describe U2fHelper do
+  describe 'when not on mobile' do
+    it 'does not inject u2f on chrome 40' do
+      device = double(mobile?: false)
+      browser = double(chrome?: true, opera?: false, version: 40, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq false
+    end
+
+    it 'injects u2f on chrome 41' do
+      device = double(mobile?: false)
+      browser = double(chrome?: true, opera?: false, version: 41, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq true
+    end
+
+    it 'does not inject u2f on opera 39' do
+      device = double(mobile?: false)
+      browser = double(chrome?: false, opera?: true, version: 39, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq false
+    end
+
+    it 'injects u2f on opera 40' do
+      device = double(mobile?: false)
+      browser = double(chrome?: false, opera?: true, version: 40, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq true
+    end
+  end
+
+  describe 'when on mobile' do
+    it 'does not inject u2f on chrome 41' do
+      device = double(mobile?: true)
+      browser = double(chrome?: true, opera?: false, version: 41, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq false
+    end
+
+    it 'does not inject u2f on opera 40' do
+      device = double(mobile?: true)
+      browser = double(chrome?: false, opera?: true, version: 40, device: device)
+      allow(helper).to receive(:browser).and_return(browser)
+      expect(helper.inject_u2f_api?).to eq false
+    end
+  end
+end