Run your emulator and install two files named com.google.android.gms and com.google.vending. As com.google.android.gms is what that is called Google play services so be sure that the apk you are installing has got the same version as your SDK's Google play services library's version. Installation of these two files is as mentioned in this link Running Google Mapsv2(見下段)
(For testing app on real device) If you are using Android 2.2 then you must add Google play services for Froyo (library) in your project rather than Google play services library. Open your SDK manager and look under Extras, you will find one. But if you are trying to test your app against Android higher than 2.2, you must go with the answers mentioned above.
