Ignore files in the Jujutsu directory (#16684)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

changelog_unreleased/cli/16684.md

@@ -0,0 +1,5 @@
+#### Ignore files in the Jujutsu directory (#16684 by @marcusirgens)
+
+The Jujutsu VCS uses the `.jj` directory, similarly to how Git uses `.git`.
+
+This change adds `.jj` to the list of directories which are silently ignored by prettier.

docs/ignore.md

@@ -24,7 +24,7 @@ coverage
 
 It’s recommended to have a `.prettierignore` in your project! This way you can run `prettier --write .` to make sure that everything is formatted (without mangling files you don’t want, or choking on generated files). And – your editor will know which files _not_ to format!
 
-By default prettier ignores files in version control systems directories (".git", ".sl", ".svn" and ".hg") and `node_modules` (unless the [`--with-node-modules` CLI option](cli.md#--with-node-modules) is specified). Prettier will also follow rules specified in the ".gitignore" file if it exists in the same directory from which it is run.
+By default prettier ignores files in version control systems directories (".git", ".jj", ".sl", ".svn" and ".hg") and `node_modules` (unless the [`--with-node-modules` CLI option](cli.md#--with-node-modules) is specified). Prettier will also follow rules specified in the ".gitignore" file if it exists in the same directory from which it is run.
 
 So by default it will be
 

src/cli/expand-patterns.js

@@ -45,7 +45,7 @@ async function* expandPatterns(context) {
  */
 async function* expandPatternsInternal(context) {
   // Ignores files in version control systems directories and `node_modules`
-  const silentlyIgnoredDirs = [".git", ".sl", ".svn", ".hg"];
+  const silentlyIgnoredDirs = [".git", ".sl", ".svn", ".hg", ".jj"];
   if (context.argv.withNodeModules !== true) {
     silentlyIgnoredDirs.push("node_modules");
   }

tests/integration/__tests__/ignore-vcs-files.js

@@ -2,6 +2,7 @@ describe("ignores files in version control systems", () => {
   runCli("cli/ignore-vcs-files", [
     ".svn/file.js",
     ".hg/file.js",
+    ".jj/file.js",
     "file.js",
     "-l",
   ]).test({

tests/integration/cli/ignore-vcs-files/.jj/file.js

@@ -0,0 +1 @@
+'use strict';