Escape the pyls executable in the command, and support running virtualenv pyls executables

ale_linters/python/pyls.vim

@@ -2,9 +2,16 @@
 " Description: A language server for Python
 
 call ale#Set('python_pyls_executable', 'pyls')
+call ale#Set('python_pyls_use_global', 0)
 
 function! ale_linters#python#pyls#GetExecutable(buffer) abort
-    return ale#Var(a:buffer, 'python_pyls_executable')
+    return ale#python#FindExecutable(a:buffer, 'python_pyls', ['pyls'])
+endfunction
+
+function! ale_linters#python#pyls#GetCommand(buffer) abort
+    let l:executable = ale_linters#python#pyls#GetExecutable(a:buffer)
+
+    return ale#Escape(l:executable)
 endfunction
 
 function! ale_linters#python#pyls#GetLanguage(buffer) abort
@@ -15,7 +22,7 @@ call ale#linter#Define('python', {
 \   'name': 'pyls',
 \   'lsp': 'stdio',
 \   'executable_callback': 'ale_linters#python#pyls#GetExecutable',
-\   'command_callback': 'ale_linters#python#pyls#GetExecutable',
+\   'command_callback': 'ale_linters#python#pyls#GetCommand',
 \   'language_callback': 'ale_linters#python#pyls#GetLanguage',
 \   'project_root_callback': 'ale#python#FindProjectRoot',
 \})

doc/ale-python.txt

@@ -189,16 +189,26 @@ g:ale_python_pylint_use_global                 *g:ale_python_pylint_use_global*
 
   See |ale-integrations-local-executables|
 
+
 ===============================================================================
 pyls                                                          *ale-python-pyls*
 
 g:ale_python_pyls_executable                     *g:ale_python_pyls_executable*
                                                  *b:ale_python_pyls_executable*
   Type: |String|
-  Default: `pyls`
+  Default: `'pyls'`
 
   See |ale-integrations-local-executables|
 
+
+g:ale_python_pyls_use_global                     *g:ale_python_pyls_use_global*
+                                                 *b:ale_python_pyls_use_global*
+  Type: |Number|
+  Default: `0`
+
+  See |ale-integrations-local-executables|
+
+
 ===============================================================================
 yapf                                                          *ale-python-yapf*
 

test/command_callback/test_pyls_command_callback.vader

@@ -0,0 +1,49 @@
+Before:
+  Save g:ale_python_pyls_executable
+  Save g:ale_python_pyls_use_global
+
+  unlet! g:ale_python_pyls_executable
+  unlet! g:ale_python_pyls_use_global
+
+  let b:bin_dir = has('win32') ? 'Scripts' : 'bin'
+
+  call ale#test#SetDirectory('/testplugin/test/command_callback')
+
+  runtime ale_linters/python/pyls.vim
+
+After:
+  Restore
+
+  unlet! b:bin_dir
+  unlet! b:executable
+
+  call ale#test#RestoreDirectory()
+  call ale#linter#Reset()
+
+Execute(The pyls command callback should return default string):
+  AssertEqual ale#Escape('pyls'),
+  \ ale_linters#python#pyls#GetCommand(bufnr(''))
+
+Execute(The pyls executable should be configurable):
+  let g:ale_python_pyls_executable = '~/.local/bin/pyls'
+
+  AssertEqual ale#Escape('~/.local/bin/pyls'),
+  \ ale_linters#python#pyls#GetCommand(bufnr(''))
+
+Execute(The pyls executable should be run from the virtualenv path):
+  call ale#test#SetFilename('python_paths/with_virtualenv/subdir/foo/bar.py')
+
+  let b:executable = ale#path#Winify(
+  \ g:dir . '/python_paths/with_virtualenv/env/' . b:bin_dir . '/pyls'
+  \)
+
+  AssertEqual ale#Escape(b:executable),
+  \ ale_linters#python#pyls#GetCommand(bufnr(''))
+
+Execute(You should be able to override the pyls virtualenv lookup):
+  call ale#test#SetFilename('python_paths/with_virtualenv/subdir/foo/bar.py')
+
+  let g:ale_python_pyls_use_global = 1
+
+  AssertEqual ale#Escape('pyls'),
+  \ ale_linters#python#pyls#GetCommand(bufnr(''))