Merge branch 'master' into custom-discarded-job-handling

1 files changed, 15 insertions, 2 deletions

diff --git a/guides/source/testing.md b/guides/source/testing.md
index 4ee3267261..f28c4c224a 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -319,6 +319,8 @@ specify to make your test failure messages clearer.
 | `assert_not_includes( collection, obj, [msg] )`                  | Ensures that `obj` is not in `collection`.|
 | `assert_in_delta( expected, actual, [delta], [msg] )`            | Ensures that the numbers `expected` and `actual` are within `delta` of each other.|
 | `assert_not_in_delta( expected, actual, [delta], [msg] )`        | Ensures that the numbers `expected` and `actual` are not within `delta` of each other.|
+| `assert_in_epsilon ( expected, actual, [epsilon], [msg] )`       | Ensures that the numbers `expected` and `actual` have a relative error less than `epsilon`.|
+| `assert_not_in_epsilon ( expected, actual, [epsilon], [msg] )`   | Ensures that the numbers `expected` and `actual` don't have a relative error less than `epsilon`.|
 | `assert_throws( symbol, [msg] ) { block }`                       | Ensures that the given block throws the symbol.|
 | `assert_raises( exception1, exception2, ... ) { block }`         | Ensures that the given block raises one of the given exceptions.|
 | `assert_instance_of( class, obj, [msg] )`                        | Ensures that `obj` is an instance of `class`.|
@@ -645,7 +647,7 @@ system tests should live.
 
 If you want to change the default settings you can change what the system
 tests are "driven by". Say you want to change the driver from Selenium to
-Poltergeist. First add the `poltergeist` gem to your Gemfile. Then in your
+Poltergeist. First add the `poltergeist` gem to your `Gemfile`. Then in your
 `application_system_test_case.rb` file do the following:
 
 ```ruby
@@ -671,6 +673,17 @@ class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
 end
 ```
 
+If you want to use a headless browser, you could use Headless Chrome or Headless Firefox by adding
+`headless_chrome` or `headless_firefox` in the `:using` argument.
+
+```ruby
+require "test_helper"
+
+class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
+  driven_by :selenium, using: :headless_chrome
+end
+```
+
 If your Capybara configuration requires more setup than provided by Rails, this
 additional configuration could be added into the `application_system_test_case.rb`
 file.
@@ -1513,7 +1526,7 @@ class BillingJobTest < ActiveJob::TestCase
 end
 ```
 
-This test is pretty simple and only asserts that the job get the work done
+This test is pretty simple and only asserts that the job got the work done
 as expected.
 
 By default, `ActiveJob::TestCase` will set the queue adapter to `:test` so that