When enabling multiple architectures, python-apt's BaseDependency may yield target_versions for a package which are for the unintended architecture when coming across a package with ':all' architecture. For example: python3-pip has a dependency on "python3:any". On AMD64 it may point to the i386 package, when having i386 architectures enabled: ``` >>> apt.Cache()["python3-pip"].candidate.dependencies[-1].target_versions [ <Version: package:'python3:i386' version:'3.6.7-1~18.04'>, <Version: package:'python3' version:'3.6.7-1~18.04'>, <Version: package:'python3:i386' version:'3.6.5-3'>, <Version: package:'python3' version:'3.6.5-3'>] ] ``` Instead, we'll look at python-apt's `or_dependencies` list, which is used to calculate the allowable target_versions: ``` >>> apt.Cache()["python3-pip"].candidate.dependencies[-1].or_dependencies <Dependency: [<BaseDependency: name:'python3:any' relation:'>=' version:'3.4~' rawtype:'Depends'>]> ``` apt.package.Dependency will provide us with the 'name', e.g. 'python3:any', and we can use this name to fetch the correct dependencies. To support installing the correct architecture, we now will pass target_arch to _mark_package_dependencies() and _get_resolved_package(). _get_resolved_package() will use the now-introduced _get_package_for_arch() method to find the correct package for the intended architecture: 1. First trying `<package-name>:<target-arch>`. 2. Then trying `<package-name>:all` in case it's a no-arch package. 3. Finally trying `<package-name>`, but logging a warning that it may be the incorrect architecture. This shouldn't happen, but the warning is there just so we'll know about it if there is a case we didn't consider. Update unit tests, cleaning out some old cruft left behind and passing without purpose. Signed-off-by: Chris Patterson <chris.patterson@canonical.com> - [ ] Have you followed the [guidelines for contributing](https://github.com/snapcore/snapcraft/blob/master/CONTRIBUTING.md)? - [ ] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [ ] Have you successfully run `./runtests.sh static`? - [ ] Have you successfully run `./runtests.sh tests/unit`? -----