Add test hosts file and basic test for Ls command; fix ls panic

.gitignore

@@ -3,3 +3,4 @@
 /hostess_*
 /coverage.out
 /coverage.html
+/.vscode

commands.go

@@ -76,7 +76,11 @@ func MaybeSaveHostFile(c *cli.Context, hostfile *Hostfile) {
 // StrPadRight adds spaces to the right of a string until it reaches l length.
 // If the input string is already that long, do nothing.
 func StrPadRight(s string, l int) string {
-	return s + strings.Repeat(" ", l-len(s))
+	r := l - len(s)
+	if r < 0 {
+		r = 0
+	}
+	return s + strings.Repeat(" ", r)
 }
 
 // Add command parses <hostname> <ip> and adds or updates a hostname in the

commands_test.go

@@ -0,0 +1,23 @@
+package hostess
+
+import (
+	"flag"
+	"os"
+	"testing"
+
+	"github.com/codegangsta/cli"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStrPadRight(t *testing.T) {
+	assert.Equal(t, "", StrPadRight("", 0), "Zero-length no padding")
+	assert.Equal(t, "          ", StrPadRight("", 10), "Zero-length 10 padding")
+	assert.Equal(t, "string", StrPadRight("string", 0), "6-length 0 padding")
+}
+
+func TestLs(t *testing.T) {
+	os.Setenv("HOSTESS_PATH", "test-fixtures/hostfile1")
+	defer os.Setenv("HOSTESS_PATH", "")
+	c := cli.NewContext(cli.NewApp(), &flag.FlagSet{}, nil)
+	Ls(c)
+}

test-fixtures/hostfile1

@@ -0,0 +1,13 @@
+#192.168.0.1 pie.dev.example.com
+192.168.0.2 cookie.example.com
+::1 hostname.pie hostname.candy cake.example.com
+fe:23b3:890e:342e::ef strawberry.pie.example.com
+# fe:23b3:890e:342e::ef dev.strawberry.pie.example.com
+192.168.1.3 pie.example.com
+127.0.1.1 robobrain
+# fe:23b3:890e:342e::ef chocolate.cake.example.com chocolate.ru.example.com chocolate.tr.example.com chocolate.cookie.example.com
+fe:23b3:890e:342e::ef chocolate.pie.example.com
+::1 localhost
+127.0.0.1 localhost
+192.168.1.1 pie.example.com
+192.168.1.1 strawberry.pie.example.com