Comment 5 for bug 1723223

https://people.debian.org/~mpitt/autopkgtest/README.package-tests.html

@builddeps@ will be replaced by the package's Build-Depends:, Build-Depends-Indep:, and build-essential. This is useful if you have many build dependencies which are only necessary for running the test suite and you don't want to replicate them in the test Depends:. However, please use this sparingly, as this can easily lead to missing binary package dependencies being overlooked if they get pulled in via build dependencies.