Factor ShellExpand from sftp backend to lib/env

lib/env/env.go

@@ -0,0 +1,23 @@
+// Package env contains functions for dealing with environment variables
+package env
+
+import (
+	"os"
+
+	homedir "github.com/mitchellh/go-homedir"
+)
+
+// ShellExpand replaces a leading "~" with the home directory" and
+// expands all environment variables afterwards.
+func ShellExpand(s string) string {
+	if s != "" {
+		if s[0] == '~' {
+			newS, err := homedir.Expand(s)
+			if err == nil {
+				s = newS
+			}
+		}
+		s = os.ExpandEnv(s)
+	}
+	return s
+}

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)
+	}
+}