gofmt fixer for Go (#970)

Add a gofmt fixer for golang.

autoload/ale/fix/registry.vim

@@ -92,6 +92,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['c', 'cpp'],
 \       'description': 'Fix C/C++ files with clang-format.',
 \   },
+\   'gofmt': {
+\       'function': 'ale#fixers#gofmt#Fix',
+\       'suggested_filetypes': ['go'],
+\       'description': 'Fix Go files with go fmt.',
+\   },
 \}
 
 " Reset the function registry to the default entries.

autoload/ale/fixers/gofmt.vim

@@ -0,0 +1,18 @@
+" Author: aliou <code@aliou.me>
+" Description: Integration of gofmt with ALE.
+
+call ale#Set('go_gofmt_executable', 'gofmt')
+call ale#Set('go_gofmt_options', '')
+
+function! ale#fixers#gofmt#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'go_gofmt_executable')
+    let l:options = ale#Var(a:buffer, 'go_gofmt_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ' -l -w'
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+    \       . ' %t',
+    \   'read_temporary_file': 1,
+    \}
+endfunction

doc/ale-go.txt

@@ -20,6 +20,16 @@ the benefit of running a number of linters, more than ALE would by default,
 while ensuring it doesn't run any linters known to be slow or resource
 intensive.
 
+===============================================================================
+gofmt                                                            *ale-go-gofmt*
+
+g:ale_go_gofmt_options                                 *g:ale_go_gofmt_options*
+                                                       *b:ale_go_gofmt_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be set to pass additional options to the gofmt fixer.
+
 ===============================================================================
 gometalinter                                              *ale-go-gometalinter*
 

doc/ale.txt

@@ -62,6 +62,7 @@ CONTENTS                                                         *ale-contents*
     glsl..................................|ale-glsl-options|
       glslang.............................|ale-glsl-glslang|
     go....................................|ale-go-options|
+      gofmt...............................|ale-go-gofmt|
       gometalinter........................|ale-go-gometalinter|
     graphql...............................|ale-graphql-options|
       gqlint..............................|ale-graphql-gqlint|

test/fixers/test_gofmt_fixer_callback.vader

@@ -0,0 +1,40 @@
+Before:
+  Save g:ale_go_gofmt_executable
+  Save g:ale_go_gofmt_options
+
+  " Use an invalid global executable, so we don't match it.
+  let g:ale_go_gofmt_executable = 'xxxinvalid'
+  let g:ale_go_gofmt_options = ''
+
+  call ale#test#SetDirectory('/testplugin/test/fixers')
+
+After:
+  Restore
+
+  call ale#test#RestoreDirectory()
+
+Execute(The gofmt callback should return the correct default values):
+  call ale#test#SetFilename('../go_files/testfile.go')
+
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command': ale#Escape('xxxinvalid')
+  \     . ' -l -w'
+  \     . ' %t',
+  \ },
+  \ ale#fixers#gofmt#Fix(bufnr(''))
+
+Execute(The gofmt callback should include custom gofmt options):
+  let g:ale_go_gofmt_options = "-r '(a) -> a'"
+  call ale#test#SetFilename('../go_files/testfile.go')
+
+  AssertEqual
+  \ {
+  \   'read_temporary_file': 1,
+  \   'command': ale#Escape('xxxinvalid')
+  \     . ' -l -w'
+  \     . ' ' . g:ale_go_gofmt_options
+  \     . ' %t',
+  \ },
+  \ ale#fixers#gofmt#Fix(bufnr(''))