feat(ivpn): allow no password for account IDs

- When matching `i-xxxx-xxxx-xxxx` username
- When matching `ivpn-xxxx-xxxx-xxxx` username

internal/configuration/settings/openvpn_test.go

@@ -0,0 +1,44 @@
+package settings
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_ivpnAccountID(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		s     string
+		match bool
+	}{
+		{},
+		{s: "abc"},
+		{s: "i"},
+		{s: "ivpn"},
+		{s: "ivpn-aaaa"},
+		{s: "ivpn-aaaa-aaaa"},
+		{s: "ivpn-aaaa-aaaa-aaa"},
+		{s: "ivpn-aaaa-aaaa-aaaa", match: true},
+		{s: "ivpn-aaaa-aaaa-aaaaa"},
+		{s: "ivpn-a6B7-fP91-Zh6Y", match: true},
+		{s: "i-aaaa"},
+		{s: "i-aaaa-aaaa"},
+		{s: "i-aaaa-aaaa-aaa"},
+		{s: "i-aaaa-aaaa-aaaa", match: true},
+		{s: "i-aaaa-aaaa-aaaaa"},
+		{s: "i-a6B7-fP91-Zh6Y", match: true},
+	}
+
+	for _, testCase := range testCases {
+		testCase := testCase
+		t.Run(testCase.s, func(t *testing.T) {
+			t.Parallel()
+
+			match := ivpnAccountID.MatchString(testCase.s)
+
+			assert.Equal(t, testCase.match, match)
+		})
+	}
+}