feat: Add Deno fmt fixer

autoload/ale/fix/registry.vim

@@ -32,6 +32,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['python'],
 \       'description': 'Fix PEP8 issues with black.',
 \   },
+\   'deno': {
+\       'function': 'ale#fixers#deno#Fix',
+\       'suggested_filetypes': ['typescript'],
+\       'description': 'Fix TypeScript using deno fmt.',
+\   },
 \   'dfmt': {
 \       'function': 'ale#fixers#dfmt#Fix',
 \       'suggested_filetypes': ['d'],

autoload/ale/fixers/deno.vim

@@ -0,0 +1,17 @@
+function! ale#fixers#deno#Fix(buffer) abort
+    let l:executable = ale#handlers#deno#GetExecutable(a:buffer)
+
+    if !executable(l:executable)
+        return 0
+    endif
+
+    let l:options = ' fmt -'
+
+    if ale#Var(a:buffer, 'deno_unstable')
+        let l:options = l:options . ' --unstable'
+    endif
+
+    return {
+    \   'command': ale#Escape(l:executable) . l:options
+    \}
+endfunction

autoload/ale/handlers/deno.vim

@@ -0,0 +1,9 @@
+" Author: Mohammed Chelouti - https://github.com/motato1
+" Description: Handler functions for Deno.
+
+call ale#Set('deno_executable', 'deno')
+call ale#Set('deno_unstable', 0)
+
+function! ale#handlers#deno#GetExecutable(buffer) abort
+    return ale#Var(a:buffer, 'deno_executable')
+endfunction

test/test_deno_executable_detection.vader

@@ -0,0 +1,19 @@
+Before:
+  runtime autoload/ale/handlers/deno.vim
+
+After:
+  unlet! g:ale_deno_executable
+
+  call ale#linter#Reset()
+
+Execute(Default executable should be detected correctly):
+  AssertEqual
+  \ 'deno',
+  \ ale#handlers#deno#GetExecutable(bufnr(''))
+
+Execute(User specified executable should override default):
+  let g:ale_deno_executable = '/path/to/deno-bin'
+  AssertEqual
+  \ '/path/to/deno-bin',
+  \ ale#handlers#deno#GetExecutable(bufnr(''))
+