fix(mdns): don't hardcode mDNS instance name (#3084)

tests/unit/test_network.cpp

@@ -0,0 +1,26 @@
+/**
+ * @file tests/unit/test_network.cpp
+ * @brief Test src/network.*
+ */
+#include <src/network.h>
+
+#include "../tests_common.h"
+
+struct MdnsInstanceNameTest: testing::TestWithParam<std::tuple<std::string, std::string>> {};
+
+TEST_P(MdnsInstanceNameTest, Run) {
+  auto [input, expected] = GetParam();
+  ASSERT_EQ(net::mdns_instance_name(input), expected);
+}
+
+INSTANTIATE_TEST_SUITE_P(
+  MdnsInstanceNameTests,
+  MdnsInstanceNameTest,
+  testing::Values(
+    std::make_tuple("shortname-123", "shortname-123"),
+    std::make_tuple("space 123", "space-123"),
+    std::make_tuple("hostname.domain.test", "hostname"),
+    std::make_tuple("&", "Sunshine"),
+    std::make_tuple("", "Sunshine"),
+    std::make_tuple("😁", "Sunshine"),
+    std::make_tuple(std::string(128, 'a'), std::string(63, 'a'))));