feat: Add benchmark example (#403)

* feat: Add benchmark example

Adds a simple benchmark example and its invocation.

* fix: Address PR comments

- Clarify meaning of `b.N`.
- Nix verbose flag in run example.

* fix: Reword b.N comment

* fix: Missing period

examples/testing/main_test.go

@@ -67,7 +67,13 @@ func TestIntMinTableDriven(t *testing.T) {
 	}
 }
 
+// Benchmark tests typically go in `_test.go` files and are
+// named beginning with `Benchmark`. The `testing` runner
+// executes each benchmark function several times, increasing
+// `b.N` on each run until it collects a precise measurement.
 func BenchmarkIntMin(b *testing.B) {
+	// Typically the benchmark runs a function we're
+	// benchmarking in a loop `b.N` times.
 	for i := 0; i < b.N; i++ {
 		IntMin(1, 2)
 	}

examples/testing/main_test.sh

@@ -16,3 +16,14 @@ $ go test -v
     --- PASS: TestIntMinTableDriven/-1,0 (0.00s)
 PASS
 ok  	examples/testing	0.023s
+
+# Run all benchmarks in the current project in verbose
+# mode. All tests are run prior to benchmarks. The `bench`
+# flag receives a regex for benchmark function names.
+$ go test -bench=.
+goos: darwin
+goarch: arm64
+pkg: examples/testing
+BenchmarkIntMin-8 1000000000 0.3136 ns/op
+PASS
+ok  	examples/testing	0.351s

examples/testing/testing.hash

@@ -1,2 +1,2 @@
-25e8941d63b555a590e6d44a95ae0e41ecadadca
-ALL2BVLkYEr
+3671aaf0eee9f6d2b68e51b09997be767edfe97c
+PlzU16wwEWE