Factor ShellExpand from sftp backend to lib/env

lib/env/env_test.go

@@ -0,0 +1,31 @@
+package env
+
+import (
+	"os"
+	"testing"
+
+	homedir "github.com/mitchellh/go-homedir"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestShellExpand(t *testing.T) {
+	home, err := homedir.Dir()
+	require.NoError(t, err)
+	require.NoError(t, os.Setenv("EXPAND_TEST", "potato"))
+	defer func() {
+		require.NoError(t, os.Unsetenv("EXPAND_TEST"))
+	}()
+	for _, test := range []struct {
+		in, want string
+	}{
+		{"", ""},
+		{"~", home},
+		{"~/dir/file.txt", home + "/dir/file.txt"},
+		{"/dir/~/file.txt", "/dir/~/file.txt"},
+		{"~/${EXPAND_TEST}", home + "/potato"},
+	} {
+		got := ShellExpand(test.in)
+		assert.Equal(t, test.want, got, test.in)
+	}
+}