gofmt fixer for Go (#970)

Add a gofmt fixer for golang.

6 files changed, 74 insertions, 0 deletions

diff --git a/autoload/ale/fix/registry.vim b/autoload/ale/fix/registry.vim
index e87b02f5..9569d215 100644
--- a/autoload/ale/fix/registry.vim
+++ b/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.
diff --git a/autoload/ale/fixers/gofmt.vim b/autoload/ale/fixers/gofmt.vim
new file mode 100644
index 00000000..66b67a9e
--- /dev/null
+++ b/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
diff --git a/doc/ale-go.txt b/doc/ale-go.txt
index 935f491f..c5a68878 100644
--- a/doc/ale-go.txt
+++ b/doc/ale-go.txt
@@ -21,6 +21,16 @@ 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*
 
 `gometalinter` is a `lint_file` linter, which only lints files that are
diff --git a/doc/ale.txt b/doc/ale.txt
index afdc918c..ba08a454 100644
--- a/doc/ale.txt
+++ b/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|
diff --git a/test/fixers/test_gofmt_fixer_callback.vader b/test/fixers/test_gofmt_fixer_callback.vader
new file mode 100644
index 00000000..14e6e063
--- /dev/null
+++ b/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(''))
diff --git a/test/go_files/testfile.go b/test/go_files/testfile.go
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/go_files/testfile.go