learn-golang-with-tdd

• https://quii.gitbook.io/learn-go-with-tests

[TOC]

Hello, World

• https://quii.gitbook.io/learn-go-with-tests/go-fundamentals/hello-world

What I learned

• if works like other programming languages, without (parenthesis)
• blocks are defined with {curly braces}
• variables are assigned declared like this: varName := value
  • I researched and realized that
    • := for short variable declarations
    • = for variable declarations and assignments.
• t.Errorf prints a message when a test fails.
• %q means "string surrounded with double quotes", in the string format context
• func greetingPrefix(language string) (prefix string) creates a named return value
  - this creates a variable called prefix in the function
  - it will be assigned the "zero" value. In this case (string): ""
• in Go, public functions start with a capital letter and private ones start with a lowercase.

Few rules to writing tests

• file name must be ${something}_test.go
• the test function must start with Test
• test function takes only one argument t *testing.T
• in order to use *testing.T type you need to import "testing"

Didn't work

# installing local documentation
go install golang.org/x/tools/cmd/godoc@latest

# after installing this command still don't work
godoc -http :8000
# ERROR: 'godoc' command not found

Starting a module

create the hello module:

mkdir hello
cd hello
go mod init hello
# check if the "go.mod" file was created

hello.go:

package main

import "fmt"

// Hello() is a separated function
// to make it testable
func Hello() string {
  return "Hello, world"
}

func main() {
  fmt.Println(Hello())
}

hello_test.go:

package main

import "testing"

func TestHello(t *testing.T) {
  got := Hello()
  want := "Hello, world"

  if got != want {
    t.Errorf("got %q want %q", got, want)
  }
}

Run the test:

go test