}
			if got := err.Error(); !strings.Contains(got, test.errstr) {
				t.Errorf("error is missing substring %q: %s", test.errstr, got)
			}
		})
	}
}

func TestParseAddrPort(t *testing.T) {
	tests := []struct {
		in      string
		want    AddrPort
		wantErr bool
	}{
		{in: "1.2.3.4:1234", want: AddrPort{mustIP("1.2.3.4"), 1234}},
		{in: "1.1.1.1:123456", wantErr: true},