Add pyflyby fixer (using its tidy-imports script) (#4219)

* add pyflyby fixer

updates

* pyflyby: add docs

updates

* add tests to pyflyby fixer

autoload/ale/fix/registry.vim

@@ -136,6 +136,11 @@ let s:default_registry = {
 \       'description': 'Apply prettier-eslint to a file.',
 \       'aliases': ['prettier-eslint'],
 \   },
+\   'pyflyby': {
+\       'function': 'ale#fixers#pyflyby#Fix',
+\       'suggested_filetypes': ['python'],
+\       'description': 'Tidy Python imports with pyflyby.',
+\   },
 \   'importjs': {
 \       'function': 'ale#fixers#importjs#Fix',
 \       'suggested_filetypes': ['javascript'],

autoload/ale/fixers/pyflyby.vim

@@ -0,0 +1,41 @@
+" Author: infokiller <joweill@icloud.com>
+" Description: Tidy imports using pyflyby's tidy-import script
+" https://github.com/deshaw/pyflyby
+
+call ale#Set('python_pyflyby_executable', 'tidy-imports')
+call ale#Set('python_pyflyby_use_global', get(g:, 'ale_use_global_executables', 0))
+call ale#Set('python_pyflyby_options', '')
+call ale#Set('python_pyflyby_auto_pipenv', 0)
+call ale#Set('python_pyflyby_auto_poetry', 0)
+
+function! ale#fixers#pyflyby#GetExecutable(buffer) abort
+    if (ale#Var(a:buffer, 'python_auto_pipenv') || ale#Var(a:buffer, 'python_pyflyby_auto_pipenv'))
+    \ && ale#python#PipenvPresent(a:buffer)
+        return 'pipenv'
+    endif
+
+    if (ale#Var(a:buffer, 'python_auto_poetry') || ale#Var(a:buffer, 'python_pyflyby_auto_poetry'))
+    \ && ale#python#PoetryPresent(a:buffer)
+        return 'poetry'
+    endif
+
+    return ale#python#FindExecutable(a:buffer, 'python_pyflyby', ['tidy-imports'])
+endfunction
+
+function! ale#fixers#pyflyby#Fix(buffer) abort
+    " let l:executable = ale#fixers#pyflyby#GetExecutable(a:buffer)
+    let l:executable = ale#fixers#pyflyby#GetExecutable(a:buffer)
+    let l:cmd = [ale#Escape(l:executable)]
+
+    if l:executable =~? 'pipenv\|poetry$'
+        call extend(l:cmd, ['run', 'tidy-imports'])
+    endif
+
+    let l:options = ale#Var(a:buffer, 'python_pyflyby_options')
+
+    if !empty(l:options)
+        call add(l:cmd, l:options)
+    endif
+
+    return {'command': join(l:cmd, ' ')}
+endfunction