test(list): Added benchmarks (#377)

Added benchmarks for the list widget (render and render half scrolled)

Cargo.toml

@@ -67,6 +67,10 @@ harness = false
 name = "block"
 harness = false
 
+[[bench]]
+name = "list"
+harness = false
+
 
 [[example]]
 name = "barchart"

benches/list.rs

@@ -0,0 +1,73 @@
+use criterion::{criterion_group, criterion_main, BatchSize, Bencher, BenchmarkId, Criterion};
+use ratatui::{
+    buffer::Buffer,
+    layout::Rect,
+    widgets::{List, ListItem, ListState, StatefulWidget, Widget},
+};
+
+/// Benchmark for rendering a list.
+/// It only benchmarks the render with a different amount of items.
+pub fn list(c: &mut Criterion) {
+    let mut group = c.benchmark_group("list");
+
+    for line_count in [64, 2048, 16384] {
+        let lines: Vec<ListItem> = (0..line_count)
+            .map(|_| ListItem::new(fakeit::words::sentence(10)))
+            .collect();
+
+        // Render default list
+        group.bench_with_input(
+            BenchmarkId::new("render", line_count),
+            &List::new(lines.clone()),
+            render,
+        );
+
+        // Render with an offset to the middle of the list and a selected item
+        group.bench_with_input(
+            BenchmarkId::new("render_scroll_half", line_count),
+            &List::new(lines.clone()).highlight_symbol(">>"),
+            |b, list| {
+                render_stateful(
+                    b,
+                    list,
+                    ListState::default()
+                        .with_offset(line_count / 2)
+                        .with_selected(Some(line_count / 2)),
+                )
+            },
+        );
+    }
+
+    group.finish();
+}
+
+/// render the list into a common size buffer
+fn render(bencher: &mut Bencher, list: &List) {
+    let mut buffer = Buffer::empty(Rect::new(0, 0, 200, 50));
+    // We use `iter_batched` to clone the value in the setup function.
+    // See https://github.com/ratatui-org/ratatui/pull/377.
+    bencher.iter_batched(
+        || list.to_owned(),
+        |bench_list| {
+            Widget::render(bench_list, buffer.area, &mut buffer);
+        },
+        BatchSize::LargeInput,
+    )
+}
+
+/// render the list into a common size buffer with a state
+fn render_stateful(bencher: &mut Bencher, list: &List, mut state: ListState) {
+    let mut buffer = Buffer::empty(Rect::new(0, 0, 200, 50));
+    // We use `iter_batched` to clone the value in the setup function.
+    // See https://github.com/ratatui-org/ratatui/pull/377.
+    bencher.iter_batched(
+        || list.to_owned(),
+        |bench_list| {
+            StatefulWidget::render(bench_list, buffer.area, &mut buffer, &mut state);
+        },
+        BatchSize::LargeInput,
+    )
+}
+
+criterion_group!(benches, list);
+criterion_main!(benches);