One of the great tools Go offers is a benchmarking command. Writing benchmarks to compare the allocation of memory and the execution time is extremely simple—it’s very similar to writing a test over a function.
We’ll use the type B, defined in the testing package (you’ll never guess what B stands for). The type B has one exposed field and an integer N, which counts the number of iterations the benchmark has executed. When running benchmarks, this field has an initial value that will allow at least a certain number of iterations to ensure that we have a steady result—no need to try and set it manually. Test benchmarking functions follow a convention very similar to test functions: their name must start with Benchmark.
In section 5.2.1 of chapter 5, we explained that using concatenation to build long strings isn’t a good idea, and you should use a builder. Don’t take our word for it; measure it yourself!
We’re building a string that represents the feedback type, which is a slice of statuses. The following listing shows the necessary code.
Listing D.1 status_internal_test.go: Examples of benchmarks
// Benchmark the string concatenation with only one value in feedback
func BenchmarkStringConcat1(b *testing.B) {
fb := feedback{absentCharacter}
for n := 0; n < b.N; n++ { #1
_ = fb.StringConcat()
}
}