Wrote url normalizer function.

url_test.go

@@ -91,3 +91,75 @@ func TestParseURL(t *testing.T) {
 		})
 	}
 }
+
+func TestNormalizeURL(t *testing.T) {
+	cases := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "strip trailing slash",
+			input:    "wss://relay.example.com/",
+			expected: "wss://relay.example.com",
+		},
+		{
+			name:     "strip multiple trailing slashes",
+			input:    "wss://relay.example.com//",
+			expected: "wss://relay.example.com",
+		},
+		{
+			name:     "strip trailing slash with path",
+			input:    "wss://relay.example.com/path/",
+			expected: "wss://relay.example.com/path",
+		},
+		{
+			name:     "lowercase scheme",
+			input:    "WSS://relay.example.com",
+			expected: "wss://relay.example.com",
+		},
+		{
+			name:     "lowercase host",
+			input:    "wss://Relay.Example.Com",
+			expected: "wss://relay.example.com",
+		},
+		{
+			name:     "strip default wss port",
+			input:    "wss://relay.example.com:443",
+			expected: "wss://relay.example.com",
+		},
+		{
+			name:     "strip default ws port",
+			input:    "ws://relay.example.com:80",
+			expected: "ws://relay.example.com",
+		},
+		{
+			name:     "preserve non-default port",
+			input:    "wss://relay.example.com:8080",
+			expected: "wss://relay.example.com:8080",
+		},
+		{
+			name:     "preserve path",
+			input:    "wss://relay.example.com/nostr",
+			expected: "wss://relay.example.com/nostr",
+		},
+		{
+			name:     "no change needed",
+			input:    "wss://relay.example.com",
+			expected: "wss://relay.example.com",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := NormalizeURL(tc.input)
+			assert.NoError(t, err)
+			assert.Equal(t, tc.expected, got)
+		})
+	}
+}
+
+func TestNormalizeURLError(t *testing.T) {
+	_, err := NormalizeURL("http://relay.example.com")
+	assert.ErrorIs(t, err, errors.InvalidProtocol)
+}