OS X - how to check if installer is signed

I'm creating installer for my application using pkgbuild and using certificate to sign it. Is there any command which would verify that created .pkg file is really signed (I mean - OS X will install it without saying that it comes from unidentified developer)? I would like to use this command as testing step in automated workflow.

You can use pkgutil --check-signature YOUR.pkg. Sample output:

Package "Silverlight.pkg":
   Status: signed by a certificate trusted by Mac OS X
   Certificate Chain:
    1. Developer ID Installer: Microsoft Corporation
   SHA1 fingerprint: AE D0 A7 C5 31 01 2B 70 D7 FB 49 5A 23 30 3A 67 05 36 5A 11
   -----------------------------------------------------------------------------
    2. Developer ID Certification Authority
   SHA1 fingerprint: 3B 16 6C 3B 7D C4 B7 51 C9 FE 2A FA B9 13 56 41 E3 88 E1 86
   -----------------------------------------------------------------------------
    3. Apple Root CA
   SHA1 fingerprint: 61 1E 5B 66 2C 59 3A 08 FF 58 D1 4A E2 24 52 D1 98 DF 6C 60

Exits with 0 on success.