ale/test/test_python_virtualenv.vader

Before:
  Save $VIRTUAL_ENV
  let $VIRTUAL_ENV = "/opt/example/"

After:
  Restore

Execute(ale#python#FindVirtualenv falls back to $VIRTUAL_ENV when no directories match):
  AssertEqual
  \  ale#python#FindVirtualenv(bufnr('%')),
  \  '/opt/example/',
  \  'Expected VIRTUAL_ENV environment variable to be used, but it was not'

Execute(ale#python#AutoVirtualenvEnvString should return the correct values):
  if has('win32')
    AssertEqual
    \ 'set PATH=/opt/example/;%PATH% && ',
    \ ale#python#AutoVirtualenvEnvString(bufnr(''))
  else
    AssertEqual
    \ 'PATH=''/opt/example/''":$PATH" ',
    \ ale#python#AutoVirtualenvEnvString(bufnr(''))
  endif