Before:
  runtime ale_linters/crystal/crystal.vim

After:
  call ale#linter#Reset()

Execute(The crystal handler should parse lines correctly and add the column if it can):
  AssertEqual
  \ [
  \   {
  \     'lnum': 2,
  \     'col': 1,
  \     'text': 'unexpected token: EOF'
  \   }
  \ ],
  \ ale_linters#crystal#crystal#Handle(255, [
  \ '[{"file":"/tmp/test.cr","line":2,"column":1,"size":null,"message":"unexpected token: EOF"}]'
  \ ])

Execute(The crystal handler should not fail when a missing file is required):
  AssertEqual
  \ [ { 'lnum':1, 'col': 1, 'text': 'while requiring "./nonexistent.cr"' } ],
  \ ale_linters#crystal#crystal#Handle(255,
  \ json_encode([
  \ { "file":"/tmp/file.cr","line":1,"column":1,"size":0,"message":"while requiring \"./nonexistent.cr\"" },
  \ { "message": "can't find file './nonexistent.cr' relative to '/tmp'" },
  \ ])
  \ )