Add alejandra for nix (#4435)

- Fixes https://github.com/dense-analysis/ale/issues/4434

7 files changed, 63 insertions, 0 deletions

diff --git a/autoload/ale/fix/registry.vim b/autoload/ale/fix/registry.vim
index 7040c4cc..b3275a32 100644
--- a/autoload/ale/fix/registry.vim
+++ b/autoload/ale/fix/registry.vim
@@ -7,6 +7,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['python'],
 \       'description': 'Add blank lines before control statements.',
 \   },
+\   'alejandra': {
+\       'function': 'ale#fixers#alejandra#Fix',
+\       'suggested_filetypes': ['nix'],
+\       'description': 'The Uncompromising Nix Code Formatter',
+\   },
 \   'align_help_tags': {
 \       'function': 'ale#fixers#help#AlignTags',
 \       'suggested_filetypes': ['help'],
diff --git a/autoload/ale/fixers/alejandra.vim b/autoload/ale/fixers/alejandra.vim
new file mode 100644
index 00000000..3844e8c0
--- /dev/null
+++ b/autoload/ale/fixers/alejandra.vim
@@ -0,0 +1,13 @@
+call ale#Set('nix_alejandra_executable', 'alejandra')
+call ale#Set('nix_alejandra_options', '')
+
+function! ale#fixers#alejandra#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'nix_alejandra_executable')
+    let l:options = ale#Var(a:buffer, 'nix_alejandra_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+    \       . ' -- -'
+    \}
+endfunction
diff --git a/doc/ale-nix.txt b/doc/ale-nix.txt
index 1df7caff..8600c281 100644
--- a/doc/ale-nix.txt
+++ b/doc/ale-nix.txt
@@ -3,6 +3,24 @@ ALE Nix Integration                                           *ale-nix-options*
 
 
 ===============================================================================
+alejandra                                                   *ale-nix-alejandra*
+
+g:ale_nix_alejandra_executable                 *g:ale_nix_alejandra_executable*
+                                               *b:ale_nix_alejandra_executable*
+  Type: |String|
+  Default: `'alejandra'`
+
+  This variable sets the executable used for alejandra.
+
+g:ale_nix_alejandra_options                       *g:ale_nix_alejandra_options*
+                                                  *b:ale_nix_alejandra_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be set to pass additional options to the alejandra fixer.
+
+
+===============================================================================
 nixfmt                                                         *ale-nix-nixfmt*
 
 g:ale_nix_nixfmt_executable                       *g:ale_nix_nixfmt_executable*
diff --git a/doc/ale-supported-languages-and-tools.txt b/doc/ale-supported-languages-and-tools.txt
index fea2fd85..705eef41 100644
--- a/doc/ale-supported-languages-and-tools.txt
+++ b/doc/ale-supported-languages-and-tools.txt
@@ -378,6 +378,7 @@ Notes:
   * `nimlsp`
   * `nimpretty`
 * nix
+  * `alejandra`
   * `nix-instantiate`
   * `nixfmt`
   * `nixpkgs-fmt`
diff --git a/doc/ale.txt b/doc/ale.txt
index 38432a60..ae783761 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -3094,6 +3094,7 @@ documented in additional help files.
     nimlsp................................|ale-nim-nimlsp|
     nimpretty.............................|ale-nim-nimpretty|
   nix.....................................|ale-nix-options|
+    alejandra.............................|ale-nix-alejandra|
     nixfmt................................|ale-nix-nixfmt|
     nixpkgs-fmt...........................|ale-nix-nixpkgs-fmt|
     statix................................|ale-nix-statix|
diff --git a/supported-tools.md b/supported-tools.md
index 45280e56..a3008b5c 100644
--- a/supported-tools.md
+++ b/supported-tools.md
@@ -387,6 +387,7 @@ formatting.
   * [nimlsp](https://github.com/PMunch/nimlsp)
   * nimpretty
 * nix
+  * [alejandra](https://github.com/kamadorueda/alejandra)
   * [nix-instantiate](http://nixos.org/nix/manual/#sec-nix-instantiate)
   * [nixfmt](https://github.com/serokell/nixfmt)
   * [nixpkgs-fmt](https://github.com/nix-community/nixpkgs-fmt)
diff --git a/test/fixers/test_alejandra_fixer_callback.vader b/test/fixers/test_alejandra_fixer_callback.vader
new file mode 100644
index 00000000..ecbab6ff
--- /dev/null
+++ b/test/fixers/test_alejandra_fixer_callback.vader
@@ -0,0 +1,24 @@
+Before:
+  Save g:ale_nix_alejandra_executable
+  Save g:ale_nix_alejandra_options
+
+After:
+  Restore
+
+Execute(The alejandra callback should return the correct default values):
+  AssertEqual
+  \ {
+  \   'command': ale#Escape('alejandra') . ' -- -'
+  \ },
+  \ ale#fixers#alejandra#Fix(bufnr(''))
+
+Execute(The alejandra executable and options should be configurable):
+  let g:ale_nix_alejandra_executable = '/path/to/alejandra'
+  let g:ale_nix_alejandra_options = '-q'
+
+  AssertEqual
+  \ {
+  \   'command': ale#Escape('/path/to/alejandra')
+  \     . ' -q -- -',
+  \ },
+  \ ale#fixers#alejandra#Fix(bufnr(''))