test: cleanup of PR 2998 to simplify (#3051)

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in kind replacement of
#2998 with the
simplified require assertion

---------

Co-authored-by: Håvard Anda Estensen <haavard.ae@gmail.com>

libs/utils/address.go

@@ -1,11 +1,14 @@
 package utils
 
 import (
+	"errors"
 	"fmt"
 	"net"
 	"strings"
 )
 
+var ErrInvalidIP = errors.New("invalid IP address or hostname given")
+
 // SanitizeAddr trims leading protocol scheme and port from the given
 // IP address or hostname if present.
 func SanitizeAddr(addr string) (string, error) {
@@ -16,7 +19,7 @@ func SanitizeAddr(addr string) (string, error) {
 	addr = strings.TrimSuffix(addr, "/")
 	addr = strings.Split(addr, ":")[0]
 	if addr == "" {
-		return "", fmt.Errorf("invalid IP address or hostname given: %s", original)
+		return "", fmt.Errorf("%w: %s", ErrInvalidIP, original)
 	}
 	return addr, nil
 }

libs/utils/address_test.go

@@ -11,6 +11,7 @@ func TestSanitizeAddr(t *testing.T) {
 	var tests = []struct {
 		addr string
 		want string
+		err  error
 	}{
 		// Testcase: trims protocol prefix
 		{addr: "http://celestia.org", want: "celestia.org"},
@@ -20,13 +21,15 @@ func TestSanitizeAddr(t *testing.T) {
 		{addr: "tcp://192.168.42.42:5050/", want: "192.168.42.42"},
 		// Testcase: invariant ip
 		{addr: "192.168.42.42", want: "192.168.42.42"},
+		// Testcase: empty addr
+		{addr: "", want: "", err: ErrInvalidIP},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.addr, func(t *testing.T) {
 			got, err := SanitizeAddr(tt.addr)
-			require.NoError(t, err)
 			require.Equal(t, tt.want, got)
+			require.ErrorIs(t, err, tt.err)
 		})
 	}
 }