*Refactor test to use events/promises and not a timer

*Add tests for peerHasItem

test.js

@@ -13,7 +13,7 @@ sodium.crypto_generichash(item1, b4a.from("item1"));
 sodium.crypto_generichash(item2, b4a.from("item2"));
 
 test("Basic presence test  / data propagation", (t) => {
-  t.plan(6);
+  t.plan(10);
 
   const peer1 = createPeer();
   const peer2 = createPeer();
@@ -51,15 +51,39 @@ test("Basic presence test  / data propagation", (t) => {
         p1.removeListener("online", handleOnline);
         p2.removeListener("online", handleOnline);
 
-        setTimeout(() => {
         t.pass("Seeing everyone online");
 
-          t.equals(true, p2.allCache.includes(peerData1[0]));
+        let p1Resolve;
+        let p2Resolve;
+        let p1Promise = new Promise((resolve) => {
+          p1Resolve = resolve;
+        });
+
+        let p2Promise = new Promise((resolve) => {
+          p2Resolve = resolve;
+        });
+
+        p1.on("item-added", () => {
           t.equals(true, p1.allCache.includes(peerData2[0]));
+          p1Resolve();
+        });
+
+        p2.on("item-added", () => {
+          t.equals(true, p2.allCache.includes(peerData1[0]));
+          p2Resolve();
+        });
+
+        Promise.all([p1Promise, p2Promise]).then(() => {
+          t.equals(true, p1.peerHasItem(peer1.keyPair.publicKey, item1));
+          t.equals(true, p2.peerHasItem(peer1.keyPair.publicKey, item1));
+
+          t.equals(true, p1.peerHasItem(peer2.keyPair.publicKey, item2));
+          t.equals(true, p2.peerHasItem(peer2.keyPair.publicKey, item2));
 
           hasFinished = true;
+
           peer2._allConnections.get(peer1.keyPair.publicKey).end();
-        }, 1000);
+        });
       }
     }