bitswap_test: make racy test less racy

fixes #4108

License: MIT
Signed-off-by: Steven Allen <steven@stebalien.com>

exchange/bitswap/bitswap_test.go

@@ -332,13 +332,26 @@ func TestBasicBitswap(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	time.Sleep(time.Millisecond * 25)
-	wl := instances[2].Exchange.WantlistForPeer(instances[1].Peer)
-	if len(wl) != 0 {
-		t.Fatal("should have no items in other peers wantlist")
+	check := func() error {
+		if len(instances[2].Exchange.WantlistForPeer(instances[1].Peer)) != 0 {
+			return fmt.Errorf("should have no items in other peers wantlist")
+		}
+
+		if len(instances[1].Exchange.GetWantlist()) != 0 {
+			return fmt.Errorf("shouldnt have anything in wantlist")
+		}
+		return nil
 	}
-	if len(instances[1].Exchange.GetWantlist()) != 0 {
-		t.Fatal("shouldnt have anything in wantlist")
+
+	for {
+		time.Sleep(time.Millisecond * 10)
+		if err := check(); err != nil {
+			if ctx.Err() != nil {
+				t.Fatal(err)
+			}
+		} else {
+			break
+		}
 	}
 
 	st0, err := instances[0].Exchange.Stat()