testing: change benchmark example function

Change to rand.Int, a function that the compiler cannot reliably eliminate.
Fix output to actual benchmark values.

Fixes #37341

Change-Id: Ifb5bf49b826ae0bdb4bf9de5a472ad0eaa54569c
Reviewed-on: https://go-review.googlesource.com/c/go/+/220397
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/testing/testing.go b/src/testing/testing.go
index 4b424e6abbd5d2509a7d15d651b0b4618726044f..83cd72fff33a0ad7a5dc9fb0999105c7c257944b 100644 (file)
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -37,17 +37,17 @@
 // https://golang.org/cmd/go/#hdr-Testing_flags
 //
 // A sample benchmark function looks like this:
-//     func BenchmarkHello(b *testing.B) {
+//     func BenchmarkRandInt(b *testing.B) {
 //         for i := 0; i < b.N; i++ {
-//             fmt.Sprintf("hello")
+//             rand.Int()
 //         }
 //     }
 //
 // The benchmark function must run the target code b.N times.
 // During benchmark execution, b.N is adjusted until the benchmark function lasts
 // long enough to be timed reliably. The output
-//     BenchmarkHello    10000000    282 ns/op
-// means that the loop ran 10000000 times at a speed of 282 ns per loop.
+//     BenchmarkRandInt-8      68453040                17.8 ns/op
+// means that the loop ran 68453040 times at a speed of 17.8 ns per loop.
 //
 // If a benchmark needs some expensive setup before running, the timer
 // may be reset: