repo: consider virtual pkgs for cache invalidation (#3177)

Virtual packages were not considered when checking if all build-packages
are satisfied between runs. Check and resolve with a warning to avoid
use of virtual packages for deterministic results.

LP: #1883546
Signed-off-by: Sergio Schvezov <sergio.schvezov@canonical.com>

Author: Sergio Schvezov

snapcraft/internal/repo/_deb.py

@@ -316,7 +316,9 @@ def _check_if_all_packages_installed(cls, package_names: List[str]) -> bool:
         with AptCache() as apt_cache:
             for package in package_names:
                 pkg_name, pkg_version = get_pkg_name_parts(package)
-                installed_version = apt_cache.get_installed_version(pkg_name)
+                installed_version = apt_cache.get_installed_version(
+                    pkg_name, resolve_virtual_packages=True
+                )
 
                 if installed_version is None or (
                     pkg_version is not None and installed_version != pkg_version

snapcraft/internal/repo/apt_cache.py

@@ -140,7 +140,19 @@ def _verify_marked_install(self, package: apt.Package):
     def is_package_valid(self, package_name: str) -> bool:
         return package_name in self.cache or self.cache.is_virtual_package(package_name)
 
-    def get_installed_version(self, package_name: str) -> Optional[str]:
+    def get_installed_version(
+        self, package_name: str, *, resolve_virtual_packages: bool = False
+    ) -> Optional[str]:
+        if resolve_virtual_packages and self.cache.is_virtual_package(package_name):
+            logger.warning(
+                f"{package_name!r} is a virtual package, use non virtual packages for deterministic results."
+            )
+            # Recusrse until a "real" package is found.
+            return self.get_installed_version(
+                self.cache.get_providing_packages(package_name)[0].name,
+                resolve_virtual_packages=resolve_virtual_packages,
+            )
+
         if package_name in self.cache:
             if self.cache[package_name].installed is not None:
                 return self.cache[package_name].installed.version

tests/spread/general/virtual-packages/task.yaml

@@ -21,7 +21,7 @@ execute: |
   fi
 
   cd "$SNAP_DIR"
-  snapcraft build
+  snapcraft build | MATCH "is a virtual package"
 
   if [ ! -f "${test_file}" ]; then
     echo "failed to install uglifyjs build package"

tests/unit/repo/test_deb.py

@@ -183,7 +183,7 @@ def setUp(self):
             fixtures.MockPatch("subprocess.check_call")
         ).mock
 
-        def get_installed_version(package_name):
+        def get_installed_version(package_name, resolve_virtual_packages=False):
             return "1.0" if "installed" in package_name else None
 
         self.fake_apt_cache.return_value.__enter__.return_value.get_installed_version.side_effect = (