[REQUIRED] Step 2: Describe your environment

• Xcode version: 8.3
• Firebase SDK version: 4.0
• Library version: 4.0
• Firebase Product: all (auth, database, storage, core, messaging, etc)

[REQUIRED] Step 3: Describe the problem

Steps to reproduce:

Unit tests for Swift projects that import Firebase fail to build
Details in http://stackoverflow.com/questions/38216090/xcode-unit-testing-with-cocoapods/39602648
Reproducible test case at https://github.com/marcelofabri/BrokenFirebase