fold: add a benchmark

Cargo.lock

@@ -3476,7 +3476,9 @@ name = "uu_fold"
 version = "0.2.2"
 dependencies = [
  "clap",
+ "codspeed-divan-compat",
  "fluent",
+ "tempfile",
  "uucore",
 ]
 

src/uu/fold/Cargo.toml

@@ -22,6 +22,15 @@ clap = { workspace = true }
 uucore = { workspace = true }
 fluent = { workspace = true }
 
+[dev-dependencies]
+divan = { workspace = true }
+tempfile = { workspace = true }
+uucore = { workspace = true, features = ["benchmark"] }
+
 [[bin]]
 name = "fold"
 path = "src/main.rs"
+
+[[bench]]
+name = "fold_bench"
+harness = false

src/uu/fold/benches/fold_bench.rs

@@ -0,0 +1,51 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use divan::{Bencher, black_box};
+use std::fmt::Write;
+use uu_fold::uumain;
+use uucore::benchmark::{create_test_file, run_util_function};
+
+/// Benchmark folding many short lines
+#[divan::bench(args = [100_000])]
+fn fold_many_lines(bencher: Bencher, num_lines: usize) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    // Create long lines that need folding
+    let data = (0..num_lines)
+        .fold(String::new(), |mut acc, i| {
+            writeln!(&mut acc, "This is a very long line number {i} that definitely needs to be folded at the default width of 80 columns").unwrap();
+            acc
+        });
+    let file_path = create_test_file(data.as_bytes(), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &[file_path_str]));
+    });
+}
+
+/// Benchmark folding with custom width
+#[divan::bench(args = [50_000])]
+fn fold_custom_width(bencher: Bencher, num_lines: usize) {
+    let temp_dir = tempfile::tempdir().unwrap();
+    let data = (0..num_lines).fold(String::new(), |mut acc, i| {
+        writeln!(
+            &mut acc,
+            "Line {i} with enough text to exceed width 40 characters and require folding"
+        )
+        .unwrap();
+        acc
+    });
+    let file_path = create_test_file(data.as_bytes(), temp_dir.path());
+    let file_path_str = file_path.to_str().unwrap();
+
+    bencher.bench(|| {
+        black_box(run_util_function(uumain, &["-w", "40", file_path_str]));
+    });
+}
+
+fn main() {
+    divan::main();
+}