issue_test.go

package issue_test

import (
	"testing"

	"github.com/expr-lang/expr"
	"github.com/expr-lang/expr/internal/testify/require"
)

func TestIssue822(t *testing.T) {
	t.Run("nil optional slice returns nil", func(t *testing.T) {
		program, err := expr.Compile(`let x = nil; x?.[0:1]`)
		require.NoError(t, err)

		out, err := expr.Run(program, nil)
		require.NoError(t, err)
		require.Nil(t, out)
	})

	t.Run("non-nil optional slice works normally", func(t *testing.T) {
		program, err := expr.Compile(`let x = [1, 2, 3]; x?.[0:2]`)
		require.NoError(t, err)

		out, err := expr.Run(program, nil)
		require.NoError(t, err)
		require.Equal(t, []interface{}{1, 2}, out)
	})

	t.Run("nil optional slice without from", func(t *testing.T) {
		program, err := expr.Compile(`let x = nil; x?.[:1]`)
		require.NoError(t, err)

		out, err := expr.Run(program, nil)
		require.NoError(t, err)
		require.Nil(t, out)
	})

	t.Run("nil optional slice without to", func(t *testing.T) {
		program, err := expr.Compile(`let x = nil; x?.[1:]`)
		require.NoError(t, err)

		out, err := expr.Run(program, nil)
		require.NoError(t, err)
		require.Nil(t, out)
	})
}