os.IsNotExist但得到“不是目录”

Question

I can not understand, why I am not able to create a folder and write to a file, and then read it in again - with the same path in same func, just for testing?
When I run "go test myio_test.go" on the file. I get

myio_test.go

...
func TestMyIo(t *testing.T) {

    myio.CreateTempJsonFile()
}
....

myio.go

package myio

import (
    "fmt"
    "io/ioutil"
    "path"
    //"syscall"
    // "os"
    "bitbucket.org/kardianos/osext"
    "os"
)

func CreateTempJsonFile() {

    exePath, _ := osext.Executable()
    filePath := path.Dir(exePath + "/json/")
    fmt.Println("create: ", filePath)

    _, errx := os.Stat(filePath)
    if os.IsNotExist(errx) {
        errm := os.Mkdir(filePath, 0644)
        if errm != nil {
            fmt.Println("error creating dir...")
            panic(errm)
        }
    }

    writeError := ioutil.WriteFile(filePath+"/user.txt", []byte(`{"user": "Mac"}`), 0644) // os.ModeTemporary)// 0644)
    if writeError == nil {
        fmt.Println("Ok write")
    } else {
        fmt.Println("Error write")
    }

    _, err := ioutil.ReadFile(filePath + "/user.txt")
    if err == nil {
        fmt.Println("Reading file")
    } else {
        fmt.Println("Error reading file")
    }
}

It is like the os.Stat(filePath) thinks the folder is already there. If I then remove the check for os.Stat() and just go and create the folder I get a panic "not a directory "?

fmt.Println("create: ", filePath) prints:

/private/var/folders/yj/jcyhsxxj6ml3tdfkp9gd2wpr0000gq/T/go-build627785093/command-line-arguments/_test/myio.test/json

It is all strange, as each test creates a new "/go-buildxxx/" folder and therefore the folder should never actually be there?

Any ideas?

Answer 1

First, you need to split off the executable from it's base path as it's returned from osext

exePath, _ := osext.Executable()
base, _ := filepath.Split(exePath)

(or use osext.ExecutableFolder())

Then you need to create the directory with the permissions 0755. Directories need the executable bit set in order to traverse them.