Fix typos in Development Testing Guide

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

doc/development/testing_guide/best_practices.md

@@ -74,7 +74,7 @@ let(:project) { create(:project) }
 let(:project) { build(:project) }
 ```
 
-[Factory Profiler](https://test-prof.evilmartians.io/#/profilers/factory_prof) can help to identify repetitive database persistance via factories.
+[Factory Profiler](https://test-prof.evilmartians.io/#/profilers/factory_prof) can help to identify repetitive database persistence via factories.
 
 ```shell
 # run test for path

doc/development/testing_guide/end_to_end/beginners_guide.md

@@ -84,7 +84,7 @@ See the [`RSpec.describe` outer block](#the-outer-rspecdescribe-block)
 
 CAUTION: **Deprecation notice:**
 The outer `context` [was deprecated](https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/550) in `13.2`
-in adherance to RSpec 4.0 specifications. Use `RSpec.describe` instead.
+in adherence to RSpec 4.0 specifications. Use `RSpec.describe` instead.
 
 ### The outer `RSpec.describe` block
 

doc/development/testing_guide/frontend_testing.md

@@ -230,7 +230,7 @@ it('exists', () => {
   // Best
 
   // NOTE: both mount and shallowMount work as long as a DOM element is available  
-  // Finds a properly formatted link with an accessable name of "Click Me"
+  // Finds a properly formatted link with an accessible name of "Click Me"
   getByRole(el, 'link', { name: /Click Me/i })
   getByRole(el, 'link', { name: 'Click Me' })
   // Finds any element with the text "Click Me"