Need to unittest golang error fs.PathError-CodePudding

Im trying to catch an error and do a unittest check for the specific error object here is the prod function Im testing:

const command = "/tmp/cmd"

type RedisAdapter struct {
    modeStatus bool
}

func (r RedisAdapter) Enable(client domain.client) error {
    cmdArgs := []string{
        "redis-job-shard-pause",
        strconv.Itoa(client.Shard()),
        strconv.Itoa(client.Duration()),
    }
    cmd := fmt.Sprintf("%v", command)
    out, err := exec.Command(cmd, cmdArgs...).Output()
    fmt.Printf("%v", string(out))
    return err
}

Unittest code that run a test when error=nil and when error=fs.PathError:

func TestEnableService_SetEnable(t *testing.T) {
    type fields struct {
        LoadEnablePort out.EnablePort
    }
    type args struct {
        client domain.Client
    }
    fileNotFound := fs.PathError{
        Op:   "fork/exec",
        Path: "/tmp/cmd",
        Err:  syscall.ENOENT,
    }
    tests := []struct {
        name   string
        fields fields
        args   args
        want   error
    }{
        {
            "Enable Redis",
            fields{
                LoadEnablePort: redis.RedisAdapter{},
            },
            args{
                client: domain.Client{},
            },
            nil,
        },
        {
            "enable_redis_cmd_not_found",
            fields{
                LoadEnablePort: redis.RedisAdapter{},
            },
            args{
                client: domain.Client{},
            },
            &fileNotFound,
        },
    }
    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            s := EnableService{
                LoadEnablePort: tt.fields.LoadEnablePort,
            }
            if got := s.LoadEnablePort.Enable(tt.args.client); got != tt.want {
                t.Errorf("LoadEnablePort.RedisAdapter.Enable = %v, want %v", got, tt.want)
            }
        })
    }
}

The nil test works fine but when I catch the second test even if the object shows exactly the same in the debugger cannot tell why the test fails:

https://i.stack.imgur.com/CTtfk.png

Notice how the "got" variable is exactly the same as the "tt.want" variable objects and in the end I have the following failed test:

=== RUN   TestEnableService_SetEnable/enable_redis_cmd_not_found
    setModeService_test.go:116: LoadEnablePort.RedisAdapter.Enable = fork/exec /tmp/cmd: no such file or directory, want fork/exec /tmp/cmd: no such file or directory
    --- FAIL: TestEnableService_SetEnable/enable_redis_cmd_not_found (549.32s)

Thanks a lot for your help.

CodePudding user response：

both error values are comparable, they hold pointers to fs.PathError structs.

Their addresses differs, thus, they are not the same.

If you were dereferencing them, they equal.

https://play.golang.org/p/ZMoEahbyIX_E

You should use errors.Is or errors.As.

Equality operator is specified here https://golang.org/ref/spec#Comparison_operators

It says

...
Interface values are comparable. 
Two interface values are equal if they have 
identical dynamic types and equal dynamic values 
or if both have value nil.
...