Fix #1566 - Add g:ale_python_flake8_change_directory

ale_linters/python/flake8.vim

@@ -1,14 +1,13 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: flake8 for python files
 
-let g:ale_python_flake8_executable =
-\   get(g:, 'ale_python_flake8_executable', 'flake8')
-
 " Support an old setting as a fallback.
 let s:default_options = get(g:, 'ale_python_flake8_args', '')
-let g:ale_python_flake8_options =
-\   get(g:, 'ale_python_flake8_options', s:default_options)
-let g:ale_python_flake8_use_global = get(g:, 'ale_python_flake8_use_global', get(g:, 'ale_use_global_executables', 0))
+
+call ale#Set('python_flake8_executable', 'flake8')
+call ale#Set('python_flake8_options', s:default_options)
+call ale#Set('python_flake8_use_global', get(g:, 'ale_use_global_executables', 0))
+call ale#Set('python_flake8_change_directory', 1)
 
 function! s:UsingModule(buffer) abort
     return ale#Var(a:buffer, 'python_flake8_options') =~# ' *-m flake8'
@@ -39,7 +38,9 @@ function! ale_linters#python#flake8#VersionCheck(buffer) abort
 endfunction
 
 function! ale_linters#python#flake8#GetCommand(buffer, version_output) abort
-    let l:cd_string = ale#path#BufferCdString(a:buffer)
+    let l:cd_string = ale#Var(a:buffer, 'python_flake8_change_directory')
+    \   ? ale#path#BufferCdString(a:buffer)
+    \   : ''
     let l:executable = ale_linters#python#flake8#GetExecutable(a:buffer)
     let l:version = ale#semver#GetVersion(l:executable, a:version_output)
 

doc/ale-python.txt

@@ -59,6 +59,17 @@ g:ale_python_black_use_global                   *g:ale_python_black_use_global*
 ===============================================================================
 flake8                                                      *ale-python-flake8*
 
+g:ale_python_flake8_change_directory     *g:ale_python_flake8_change_directory*
+                                         *b:ale_python_flake8_change_directory*
+  Type: |Number|
+  Default: `1`
+
+  If set to `1`, ALE will switch to the directory the Python file being
+  checked with `flake8` is in before checking it. This helps `flake8` find
+  configuration files more easily. This option can be turned off if you want
+  to control the directory Python is executed from yourself.
+
+
 g:ale_python_flake8_executable                 *g:ale_python_flake8_executable*
                                                *b:ale_python_flake8_executable*
   Type: |String|

test/command_callback/test_flake8_command_callback.vader

@@ -2,11 +2,13 @@ Before:
   Save g:ale_python_flake8_executable
   Save g:ale_python_flake8_options
   Save g:ale_python_flake8_use_global
+  Save g:ale_python_flake8_change_directory
 
   unlet! g:ale_python_flake8_executable
   unlet! g:ale_python_flake8_args
   unlet! g:ale_python_flake8_options
   unlet! g:ale_python_flake8_use_global
+  unlet! g:ale_python_flake8_change_directory
 
   let b:bin_dir = has('win32') ? 'Scripts' : 'bin'
 
@@ -44,6 +46,13 @@ Execute(The flake8 callbacks should return the correct default values):
   \   . ale#Escape('flake8') . ' --format=default -',
   \ ale_linters#python#flake8#GetCommand(bufnr(''), ['2.9.9'])
 
+Execute(The option for disabling changing directories should work):
+  let g:ale_python_flake8_change_directory = 0
+
+  AssertEqual
+  \ ale#Escape('flake8') . ' --format=default --stdin-display-name %s -',
+  \ ale_linters#python#flake8#GetCommand(bufnr(''), ['3.0.0'])
+
 Execute(The flake8 command callback should let you set options):
   let g:ale_python_flake8_options = '--some-option'