package output

import (
	"bytes"
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestColorsEnabled_BufferIsNotTTY(t *testing.T) {
	t.Setenv("NO_COLOR", "")
	// Explicitly unset NO_COLOR so the non-TTY branch is exercised.
	t.Setenv("NO_COLOR", "")
	assert.False(t, ColorsEnabled(&bytes.Buffer{}), "bytes.Buffer must never be considered a TTY")
}

func TestColorsEnabled_NoColorEnvForcesOff(t *testing.T) {
	t.Setenv("NO_COLOR", "1")
	assert.False(t, ColorsEnabled(&bytes.Buffer{}))
}

func TestColorsEnabled_NilWriterSafe(t *testing.T) {
	t.Setenv("NO_COLOR", "")
	// A nil *os.File should return false, not panic.
	var f *nilWriter
	assert.False(t, ColorsEnabled(f))
}

// nilWriter is a typed-nil io.Writer used to verify ColorsEnabled does not
// panic when passed a non-*os.File writer.
type nilWriter struct{}

func (*nilWriter) Write(p []byte) (int, error) { return len(p), nil }

func TestIsTTY_NilFile(t *testing.T) {
	assert.False(t, IsTTY(nil))
}