Writing a Go-Based CLI Tool for Benchmark Testing

Introduction
Prerequisites
Setup
Creating the CLI Tool
Running Benchmark Tests
Conclusion

Introduction

In this tutorial, we will learn how to write a command-line interface (CLI) tool using the Go programming language for benchmark testing. We will create a tool that allows us to run benchmark tests on our code to measure its performance and identify any potential performance issues. By the end of this tutorial, you will have a basic understanding of how to create a Go-based CLI tool and use it to run benchmark tests.

Prerequisites

Before starting this tutorial, you should have the following:

Basic knowledge of the Go programming language
Go installed on your system
Familiarity with the command line

Setup

To begin, let’s set up our development environment by following these steps:

Install Go on your system by visiting the Go Downloads page (https://golang.org/dl/) and selecting the appropriate installer for your operating system.
After installing Go, open a terminal or command prompt and verify that Go is correctly installed by running the following command: shell go version
```
This command should display the installed Go version.
```
Set up a workspace for your Go projects. Create a new directory on your system where you would like to store your Go code. This directory will be referred to as your “workspace.”
Set the GOPATH environment variable to the path of your workspace. You can set this variable by adding the following line to your shell’s configuration file (e.g., .bashrc, .zshrc, or .profile): shell export GOPATH=/path/to/your/workspace
```
Replace `/path/to/your/workspace` with the actual path to your workspace directory.
```

Update your shell’s configuration by running the following command: shell source ~/.bashrc

Note: If you are using a different shell configuration file, replace `~/.bashrc` with the path to your specific configuration file.

Verify that your workspace is set up correctly by running the following command: shell echo $GOPATH
```
This command should display the path to your workspace directory.
```

Creating the CLI Tool

Now that our development environment is set up, let’s start creating our Go-based CLI tool:

Open a text editor or an integrated development environment (IDE) of your choice.
Create a new file called benchmark.go in your workspace.

Start by adding the following code to import the necessary packages: ```go package main

import (
    "flag"
    "fmt"
    "testing"
)
```

- The `flag` package is used to define command-line flags and options.
- The `fmt` package provides functions for formatted I/O.
- The `testing` package is used for benchmark testing.

Next, define the command-line flags and options by adding the following code: ```go var ( runs int duration int )

func init() {
    flag.IntVar(&runs, "runs", 5, "number of benchmark test runs")
    flag.IntVar(&duration, "duration", 1, "duration of each benchmark test in seconds")
}
```

- The `runs` variable represents the number of benchmark test runs.
- The `duration` variable represents the duration of each benchmark test in seconds.
- The `flag.IntVar` function is used to define integer command-line flags. In this case, we are using it to define the `-runs` and `-duration` flags.

Create a function called runBenchmark to perform the benchmark test. Add the following code: go func runBenchmark() { // TODO: Implement your benchmark test here }
```
This function will be called when the user runs the CLI tool with the `benchmark` command.
```

In the main function, add the following code to parse the command-line flags and execute the appropriate command: ```go func main() { flag.Parse()

    if flag.NArg() == 0 {
        fmt.Println("Usage: benchmark [command]")
        fmt.Println()
        fmt.Println("Commands:")
        fmt.Println("  run      Run benchmark tests")
        return
    }

    command := flag.Args()[0]

    switch command {
    case "run":
        runBenchmark()
    default:
        fmt.Printf("Unknown command: %s\n", command)
    }
}
```

- The `flag.NArg` function returns the number of arguments after the command-line flags.
- If no command is provided, the CLI tool will display usage information and available commands.
- We use a `switch` statement to execute the appropriate command based on the user's input.

Save the benchmark.go file.
Open a terminal or command prompt and navigate to your workspace.
Build the CLI tool by running the following command: shell go build benchmark.go
Verify that the CLI tool was built successfully by running the following command: shell ./benchmark
```
This command should display the available commands.
```
Congratulations! You have now created a basic Go-based CLI tool for benchmark testing. Next, let’s learn how to run benchmark tests using this tool.

Running Benchmark Tests

Now that we have our CLI tool set up, let’s learn how to use it to run benchmark tests on our code:

Decide which function or code snippet you want to benchmark and replace the // TODO: Implement your benchmark test here comment in the runBenchmark function with your own benchmark test code.

For example, let's say we want to benchmark a function called `MyFunction`:
```go
func MyFunction() {
    // Some code to be benchmarked
}
```

We can replace the `// TODO: Implement your benchmark test here` comment with the following code:
```go
func runBenchmark() {
    testing.Benchmark(func(b *testing.B) {
        for n := 0; n < b.N; n++ {
            MyFunction()
        }
    })
}
```

This code uses the `testing.Benchmark` function to execute the benchmark test.

Save the benchmark.go file.
Rebuild the CLI tool by running the following command again: shell go build benchmark.go

Run the benchmark test by executing the following command: shell ./benchmark run

This command will run the benchmark test using the default number of runs (5) and duration (1 second).

You can customize the number of runs and duration by providing the `-runs` and `-duration` flags. For example:
```shell
./benchmark run -runs=10 -duration=2
```

After running the benchmark test, you will see the output containing the test results, including the number of iterations, time per iteration, and memory allocations.
```
For example:
```
goos: darwin
goarch: amd64
BenchmarkMyFunction-8   	 1000000	     1006 ns/op	      80 B/op	       1 allocs/op
```

This output shows that the benchmark test for `MyFunction` executed 1 million iterations, with an average time of approximately 1006 nanoseconds per iteration. It also shows the memory allocations per iteration.
```
Congratulations! You have now successfully written a Go-based CLI tool for benchmark testing and learned how to run benchmark tests on your code. You can customize the benchmark tests for different functions or code snippets based on your requirements.

Conclusion

In this tutorial, we have learned how to write a Go-based CLI tool for benchmark testing. We have set up our development environment, created the CLI tool, and ran benchmark tests on our code. By following this tutorial, you should now have a basic understanding of how to create your own CLI tools using Go and use them for benchmark testing.

Remember to explore the various options and functionalities provided by the testing package to customize your benchmark tests further. Additionally, you can extend your CLI tool to include additional commands or features based on your specific needs.

Happy benchmarking!

Published: 7 February 2020