add a test case for libp2p option prioritization

core/node/libp2p/libp2p_test.go

@@ -0,0 +1,58 @@
+package libp2p
+
+import (
+	"fmt"
+	"strconv"
+	"testing"
+
+	"github.com/libp2p/go-libp2p"
+	ma "github.com/multiformats/go-multiaddr"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPrioritize(t *testing.T) {
+	// The option is encoded into the port number of a TCP multiaddr.
+	// By extracting the port numbers obtained from the applied option, we can make sure that
+	// prioritization sorted the options correctly.
+	newOption := func(num int) libp2p.Option {
+		return func(cfg *libp2p.Config) error {
+			cfg.ListenAddrs = append(cfg.ListenAddrs, ma.StringCast(fmt.Sprintf("/ip4/127.0.0.1/tcp/%d", num)))
+			return nil
+		}
+	}
+
+	extractNums := func(cfg *libp2p.Config) []int {
+		addrs := cfg.ListenAddrs
+		nums := make([]int, 0, len(addrs))
+		for _, addr := range addrs {
+			_, comp := ma.SplitLast(addr)
+			num, err := strconv.Atoi(comp.Value())
+			require.NoError(t, err)
+			nums = append(nums, num)
+		}
+		return nums
+	}
+
+	t.Run("using default priorities", func(t *testing.T) {
+		opts := []priorityOption{
+			{defaultPriority: 200, opt: newOption(200)},
+			{defaultPriority: 1, opt: newOption(1)},
+			{defaultPriority: 300, opt: newOption(300)},
+		}
+		var cfg libp2p.Config
+		require.NoError(t, prioritizeOptions(opts)(&cfg))
+		require.Equal(t, extractNums(&cfg), []int{1, 200, 300})
+	})
+
+	t.Run("using custom priorities", func(t *testing.T) {
+		opts := []priorityOption{
+			{defaultPriority: 200, priority: 1, opt: newOption(1)},
+			{defaultPriority: 1, priority: 300, opt: newOption(300)},
+			{defaultPriority: 300, priority: 20, opt: newOption(20)},
+		}
+		var cfg libp2p.Config
+		require.NoError(t, prioritizeOptions(opts)(&cfg))
+		require.Equal(t, extractNums(&cfg), []int{1, 20, 300})
+	})
+}