test: add display bench

Cargo.toml

@@ -24,11 +24,16 @@ arbitrary = { version = "1", optional = true }
 serde = { version = "1", optional = true }
 
 [dev-dependencies]
+divan = "0.1"
 quickcheck = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 toml = "0.8"
 
+[[bench]]
+name = "display"
+harness = false
+
 [lints.rust]
 rust-2018-idioms = { level = "deny" }
 future-incompatible = { level = "deny" }

benches/display.rs

@@ -0,0 +1,47 @@
+#![allow(missing_docs, clippy::incompatible_msrv)]
+
+use std::{env, fmt, hint::black_box};
+
+struct ByteSizeAlwaysPad(bytesize::ByteSize);
+
+impl fmt::Display for ByteSizeAlwaysPad {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad(&self.0.display().to_string())
+    }
+}
+
+#[divan::bench]
+fn display_inner_display() {
+    black_box(format!("{}", bytesize::ByteSize::kib(42).display()));
+}
+
+#[divan::bench]
+fn display_bytesize_standard() {
+    black_box(format!("{}", bytesize::ByteSize::kib(42).display()));
+}
+
+#[divan::bench]
+fn display_bytesize_custom() {
+    black_box(format!("|{:-^10}|", bytesize::ByteSize::kib(42)));
+}
+
+#[divan::bench]
+fn display_always_pad_standard() {
+    black_box(format!(
+        "{}",
+        ByteSizeAlwaysPad(bytesize::ByteSize::kib(42))
+    ));
+}
+
+#[divan::bench]
+fn display_always_pad_custom() {
+    black_box(format!(
+        "|{:-^10}|",
+        ByteSizeAlwaysPad(bytesize::ByteSize::kib(42))
+    ));
+}
+
+fn main() {
+    env::set_var("DIVAN_SAMPLE_COUNT", "1000");
+    divan::main();
+}