fix(cluster): resolve localhost with digResolver as well

Closes #171

src/cluster/resolvers.spec.ts

@@ -11,7 +11,7 @@ jest.mock('util', () => ({
 
 describe('resolvers', () => {
   beforeEach(async () => {
-    jest.clearAllMocks();
+    jest.resetAllMocks();
   });
 
   it('should return a single address correctly', (done) => {
@@ -65,6 +65,29 @@ describe('resolvers', () => {
     });
   });
 
+  it('should return localhost correctly', (done) => {
+    const service: Service = {
+      addresses: undefined,
+      flags: undefined,
+      fullname: undefined,
+      host: 'localhost.',
+      interfaceIndex: undefined,
+      networkInterface: undefined,
+      port: undefined,
+      replyDomain: undefined,
+      type: undefined,
+    };
+
+    getAddrInfoDig(service, () => {
+      try {
+        expect(service.addresses).toStrictEqual(['127.0.0.1']);
+        done();
+      } catch (e) {
+        done(e);
+      }
+    });
+  });
+
   it('should pass errors to the callback', (done) => {
     const service: Service = {
       addresses: undefined,

src/cluster/resolvers.ts

@@ -15,6 +15,11 @@ export async function getAddrInfoDig(
   service: Service,
   next: (e?: Error) => void
 ): Promise<void> {
+  if (service.host === 'localhost' || service.host === 'localhost.') {
+    service.addresses = (service.addresses || []).concat(['127.0.0.1']);
+    next();
+  }
+
   try {
     const digOutput = await execPromise(
       `dig +short @224.0.0.251 -p 5353 -4 ${service.host}`