Monthly Archives: December 2015

Notes on Go, part 3 of ∞

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Here are my notes on how multiple returns work.

package main

import "fmt"

func split(sum int) (x, y int) {
    x = sum * 4 / 9
    y = sum - x
    return
}

func main() {
    results := split(17)
    fmt.Println(results)
    fmt.Println(split(17))
}

Returns prog.go:12: multiple-value split() in single-value context (Check it out on the Go Playground)

package main

import "fmt"

func split(sum int) (x, y int) {
    x = sum * 4 / 9
    y = sum - x
    return
}

func main() {
    resultsx, resultsy := split(17)
    fmt.Println(resultsx)
    fmt.Println(resultsy)
    fmt.Println(split(17))
}

Returns:

7
10
7 10

(Check it out on the Go Playground)

If a function returns multiple things, you are required to give each of those things a name if you are going to save them to a variable. The exception (so far) is if you directly pass the function to another function that can handle that sort of thing.

If you don’t want to save one of the returns, you can assign it to _, which basically says ‘I know there is going to be something here, throw it out immediately’.

Notes on Go, part 2 of ∞

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Why aren’t my test running?

The command go test will only pick up tests in the directory that the command is being run in. To have it find tests in sub-folders, try the command go test ./.... This searches recursively through the sub-folders and finds the hiding tests and runs them.

Tests still aren’t running? If you are using godep to manage dependancies, you can try:

godep get

Still getting error messages á la:

somefolder/some_test.go:10:2: cannot find package "github.com/THING/code" in any of:
    /usr/local/Cellar/go/1.5.1/libexec/src/github.com/THING/code (from $GOROOT)
    ~/code/go/src/github.com/THING/code (from $GOPATH)

Try the following series of commands from the root directory of your project.

godep restore
rm -rf Godeps
godep save ./...
godep go test ./...
go test ./...

Stay tuned for an actual explanation of why any of this works when I figure it out!

Notes on Go, part 1 of ∞

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When writing tests in Go, there are a few useful ways to get info printed out to the screen.

  • t.log

Inside the test, you can log stuff using t.log. This will only show up if you use the -v flag when running go test.

  • fmt.PrintLn

Inside the actual program itself, you can print things using an fmt.Print command, and running the tests with the -v flag.

Basically, the -v flag is your friend when you want to see things in your go tests!