I have implemented project by using third party library(zxing) after implementation project is working fine then after I have written one test project to unit test my projec
I got this error because I was working with Guava and Espresso also contains Guava.
If you use Gradle and Android Studio you can exclude packages from the dependency like this:
androidTestCompile('com.jakewharton.espresso:espresso:1.1-r3') { exclude group: 'com.google.guava' }