feat(formatter): add buf protobuf formatter (#65)

Author: barrettruth

lua/guard-collection/formatter.lua

@@ -311,6 +311,12 @@ M.biome = {
   stdin = true,
 }
 
+M.buf = {
+  cmd = 'buf',
+  args = { 'format' },
+  stdin = true,
+}
+
 M.xmllint = {
   cmd = 'xmllint',
   args = { '--format', '-' },

test/formatter/buf_spec.lua

@@ -0,0 +1,17 @@
+describe('buf', function()
+  it('can format', function()
+    local ft = require('guard.filetype')
+    ft('proto'):fmt('buf')
+
+    local formatted = require('test.formatter.helper').test_with('proto', {
+      [[syntax = "proto3"; message Foo { string bar = 1; }]],
+    })
+    assert.are.same({
+      [[syntax = "proto3";]],
+      [[]],
+      [[message Foo {]],
+      [[  string bar = 1;]],
+      [[}]],
+    }, formatted)
+  end)
+end)