types: Flesh out address comparison and string formatting

Change-Id: Ib505232e15e8db012d07759163f780b00ea4b7d3
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/test/test_ethernet_interface.cpp b/test/test_ethernet_interface.cpp
index f8254b0..ace2b1d 100644
--- a/test/test_ethernet_interface.cpp
+++ b/test/test_ethernet_interface.cpp
@@ -117,7 +117,7 @@
                                "/xyz/openbmc_test/network"sv, config::Parser());
 
     EXPECT_EQ(mtu, intf.mtu());
-    EXPECT_EQ(mac_address::toString(mac), intf.macAddress());
+    EXPECT_EQ(std::to_string(mac), intf.macAddress());
     EXPECT_TRUE(intf.linkUp());
 }