@faizmokh's blog

How to use Go examples and benchmarks

03 Aug, 2018

I learned about Go examples and benchmarks today. They are parts of Go default package testing.

Examples

Go Examples are executed just like tests
They are compiled and optionally executed as part of unit tests
It resides in the package *_test.go files

Structure

1func ExampleRepeat() {
2  repeated := Repeated("x", 5)
3  fmt.Println(repeated)
4  // output: xxxxx
5}

Rules

Function name must be prefix with Example
It must have // output: result

How to Use

to run the test with example, use: go test -v

Sample Execution

1$ go test -v
2=== RUN   TestRepeat
3--- PASS: TestRepeat (0.00s)
4=== RUN   ExampleRepeat
5--- PASS: ExampleRepeat (0.00s)

Extras

It will not run if you remove the // output comment.
These examples can be display in godoc as part of the documentations
To see the examples, run go doc -http:6060 and navigate to http://localhost:6060/pkg/ and you will find the examples in the package documentation.

Benchmarks

Just like Examples above, Benchmarks are executed by go test

Structure

1func BenchmarkRepeat(b *testing.B) {
2	for i := 0; i < b.N; i++ {
3		Repeat("a", 100)
4	}
5}

Rules

Function name must be prefix with Benchmark
testing.B give you access to b.N.
During benchmarking process, it will run b.N times and measure the duration it takes

How to Use

To run the test with benchmarks, use: go test -bench=.

Sample Execution

1$ go test -bench=.
2goos: darwin
3goarch: amd64
4pkg: github.com/faizmokhtar/go-with-test/3-repeat
5BenchmarkRepeat-8         300000              5485 ns/op
6PASS
7ok      github.com/faizmokhtar/go-with-test/3-repeat    1.714s

References: