Before:
  runtime autoload/ale/handlers/atools.vim

After:
  call ale#linter#Reset()

Execute(The atools handler should handle basic errors or warings):
  AssertEqual
  \ [
  \   {
  \     'lnum': 2,
  \     'text': 'trailing whitespace',
  \     'type': 'E',
  \     'code': 'AL8',
  \   },
  \   {
  \     'lnum': 15,
  \     'text': '$pkgname should not be used in the source url',
  \     'type': 'W',
  \     'code': 'AL29',
  \   },
  \ ],
  \ ale#handlers#atools#Handle(bufnr(''), [
  \   'IC:[AL8]:APKBUILD:2:trailing whitespace',
  \   'MC:[AL29]:APKBUILD:15:$pkgname should not be used in the source url',
  \ ])

" Regardless of the severity, if the certainty is [P]ossible and not [C]ertain
" or if regardless of the Certainty the Severity is not [I]mportant or [S]erious
" then it must be a [W]arning
Execute(If we are not Certain or Importantly Serious, be a Warning):
  AssertEqual
  \ [
  \   {
  \     'lnum': 3,
  \     'text': 'This violation is Serious but Possible false positive, I am a Warning!',
  \     'type': 'W',
  \     'code': 'AL',
  \   },
  \   {
  \     'lnum': 4,
  \     'text': 'This violation is Important but Possible false positive, I am a Warning!',
  \     'type': 'W',
  \     'code': 'AL',
  \   },
  \   {
  \     'lnum': 5,
  \     'text': 'This violation is Minor, I am a Warning!',
  \     'type': 'W',
  \     'code': 'AL',
  \   },
  \   {
  \     'lnum': 6,
  \     'text': 'This violation is Style, I am a Warning!',
  \     'type': 'W',
  \     'code': 'AL',
  \   },
  \ ],
  \ ale#handlers#atools#Handle(bufnr(''), [
  \   'SP:[AL]:APKBUILD:3:This violation is Serious but Possible false positive, I am a Warning!',
  \   'IP:[AL]:APKBUILD:4:This violation is Important but Possible false positive, I am a Warning!',
  \   'MC:[AL]:APKBUILD:5:This violation is Minor, I am a Warning!',
  \   'TC:[AL]:APKBUILD:6:This violation is Style, I am a Warning!',
  \ ])

Execute(We should be error if we are Certain it is Serious or Important):
  AssertEqual
  \ [
  \   {
  \     'lnum': 7,
  \     'text': 'This is Certainly Serious, I am an Error!',
  \     'type': 'E',
  \     'code': 'AL',
  \   },
  \   {
  \     'lnum': 8,
  \     'text': 'This is Certainly Important, I am an Error!',
  \     'type': 'E',
  \     'code': 'AL',
  \   },
  \ ],
  \ ale#handlers#atools#Handle(bufnr(''), [
  \    'SC:[AL]:APKBUILD:7:This is Certainly Serious, I am an Error!',
  \    'IC:[AL]:APKBUILD:8:This is Certainly Important, I am an Error!',
  \ ])