[fix] Don't skip hidden dot-directories when walking a directory argument

WalkBuilder ignores hidden files by default, so `rubyfmt --check .` (or
`-i .`) silently never visits .rb files under dot-directories like
.buildkite/ or .github/ even when they're tracked in git and not excluded
by any .gitignore/.rubyfmtignore pattern. Passing an explicit file path
bypasses the walk entirely and is unaffected, which made the gap easy to
miss: `rubyfmt --check .buildkite/pipeline.rb` catches problems that
`rubyfmt --check .` does not.

Un-hide dotfiles in the walk and explicitly filter out .git, since that's
the one dot-directory we never want to walk into regardless.

Author: dduugg

src/main.rs

@@ -232,6 +232,12 @@ fn file_walker_builder(include_paths: Vec<&String>, include_gitignored: bool) ->
 
     builder.git_ignore(!include_gitignored);
     builder.add_custom_ignore_filename(".rubyfmtignore");
+
+    // WalkBuilder ignores hidden files by default, dropping .rb files under
+    // dot-directories like .buildkite/. Un-hide dotfiles, but keep .git out.
+    builder.hidden(false);
+    builder.filter_entry(|entry| entry.file_name() != OsStr::new(".git"));
+
     builder
 }
 

tests/cli_interface_test.rs

@@ -461,6 +461,58 @@ fn test_format_directory_with_changes() {
     assert_eq!("a(4, 5, 6)\n", read_to_string(file_two.path()).unwrap());
 }
 
+#[test]
+fn test_format_directory_with_changes_in_hidden_directory() {
+    // Hidden directories should not be skipped when walking a directory argument.
+    let dir = tempdir().unwrap();
+    let dir_name = dir.path().to_str().unwrap().to_owned();
+    create_dir(dir_name.clone() + "/.hidden").unwrap();
+
+    let mut file = tempfile::Builder::new()
+        .prefix("rubyfmt")
+        .suffix(".rb")
+        .tempfile_in(dir_name.clone() + "/.hidden")
+        .unwrap();
+    writeln!(file, "a 1, 2, 3").unwrap();
+
+    Command::cargo_bin("rubyfmt-main")
+        .unwrap()
+        .arg(dir_name)
+        .arg("-i")
+        .assert()
+        .stdout("")
+        .code(0)
+        .success();
+
+    assert_eq!("a(1, 2, 3)\n", read_to_string(file.path()).unwrap());
+}
+
+#[test]
+fn test_format_directory_ignores_git_directory() {
+    // .git should still be skipped even though hidden directories are walked now.
+    let dir = tempdir().unwrap();
+    let dir_name = dir.path().to_str().unwrap().to_owned();
+    create_dir(dir_name.clone() + "/.git").unwrap();
+
+    let mut file = tempfile::Builder::new()
+        .prefix("rubyfmt")
+        .suffix(".rb")
+        .tempfile_in(dir_name.clone() + "/.git")
+        .unwrap();
+    writeln!(file, "a 1, 2, 3").unwrap();
+
+    Command::cargo_bin("rubyfmt-main")
+        .unwrap()
+        .arg(dir_name)
+        .arg("-i")
+        .assert()
+        .stdout("")
+        .code(0)
+        .success();
+
+    assert_eq!("a 1, 2, 3\n", read_to_string(file.path()).unwrap());
+}
+
 #[test]
 fn format_input_file_with_changes() {
     let mut file_one = NamedTempFile::new().unwrap();