Stuck on testing Ethernet Class

.arduino-ci.yml

@@ -16,13 +16,14 @@ unittest:
     platforms:
         - mega2560
     libraries:
+      - "Ethernet"
       - "LiquidCrystal"
       - "RTClib"
 
 compile:
     platforms:
       - mega2560
     libraries:
+      - "Ethernet"
       - "LiquidCrystal"
       - "RTClib"
-

src/Devices/Ethernet_TC.cpp

@@ -0,0 +1,31 @@
+#include "Ethernet_TC.h"
+
+Ethernet_TC *Ethernet_TC::_instance = nullptr;
+
+// Establishes the Ethenet connection and sets class variables
+Ethernet_TC::Ethernet_TC() {
+  pinMode(4, OUTPUT);
+  digitalWrite(4, HIGH);
+  if (Ethernet.begin(mac) == 0) {
+    Serial.println(F("Failed to configure Ethernet using DHCP"));
+    IPAddress defaultIP = IPAddress(192, 168, 1, 2);
+    Ethernet.begin(mac, defaultIP);
+    IP = defaultIP;
+  }
+}
+
+Ethernet_TC *Ethernet_TC::getInstance() {
+  if (_instance == nullptr) {
+    _instance = new Ethernet_TC;
+  }
+  return _instance;
+}
+
+void Ethernet_TC::renewDHCPLease() {
+  unsigned long current_millis = millis();
+
+  if (current_millis - previous_lease >= LEASE_INTERVAL) {
+    Ethernet.maintain();
+    previous_lease = current_millis;
+  }
+}

src/Devices/Ethernet_TC.h

@@ -0,0 +1,29 @@
+/*
+Based off Arduino's Ethernet library
+Implements a wrapper for the Ethernet Class
+*/
+
+#pragma once
+
+#include "Ethernet.h"
+
+class Ethernet_TC {
+public:
+  static Ethernet_TC *getInstance();
+  IPAddress getIP() {
+    return IP;
+  };
+  void renewDHCPLease();
+
+protected:
+  Ethernet_TC();
+
+private:
+  static Ethernet_TC *_instance;
+  byte mac[6] = {0x90, 0xA2, 0xDA, 0x00, 0x00, 0x00};
+  IPAddress defaultIP;
+  IPAddress time_serverIP;
+  IPAddress IP;
+  unsigned long previous_lease;
+  const unsigned long LEASE_INTERVAL = 345600000;  // 4 days in milliseconds
+};

test/Ethernet.cpp

@@ -0,0 +1,10 @@
+#include <Arduino.h>
+#include <ArduinoUnitTests.h>
+
+#include "Ethernet_TC.h"
+
+unittest(test) {
+  assertTrue(true);
+}
+
+unittest_main()