koanf.Unmarshal doesn't work when loaded with env provider

[nomikz]

Description:

koanf.Unmarshal doesn't work when loaded by env provider

Is this expected behaviour?

Test: this test has no dependencies like files, envrionemnt variables.

package config

import (
    "os"
    "testing"

    "github.com/knadh/koanf/providers/env"
    koanf "github.com/knadh/koanf/v2"
    "github.com/stretchr/testify/require"
)

type Conf struct {
    Key string `koanf:"key"`
}

func TestTest(t *testing.T) {
    k := koanf.New("")

    // Set env variable
    require.NoError(t, os.Setenv("key", "value"))

    // Load environment variables
    err := k.Load(env.Provider("", "", nil), nil)
    require.NoError(t, err)
    // This passes successfully
    require.Equal(t, "value", k.String("key")) 

    var c Conf
    err = k.Unmarshal("", &c)
    require.NoError(t, err)

    // Here, it is expected that value is unmarshalled  
    require.Equal(t, "value", c.Key)
}

Expected behavior Value must have been successfully unmarshalled into a struct.

OS: macOS Sonama Version 14.3.1
Koanf Version: v2.1.0

[wass3r]

in case you didn't know, it works when you provide a delimiter: env.Provider("", ".", nil)

[nomikz]

@wass3r thanks. But this is undefined behaviour. Although I didn't provide delimeter, accessing with k.String("key") in above example works fine. However, the field didn't get unmarshalled.