package: Use package expressions in Packages component

- managed_packages() finds all possible packages that could be
  installed. This is used for the check in the action script.

- resolve() finds actual packages to be installed. This is used in
  setup, diagnose, and has_unavailable_packages.

Signed-off-by: James Valleroy <jvalleroy@mailbox.org>

actions/packages

@@ -131,7 +131,7 @@ def _assert_managed_packages(module, packages):
         app = cls()
         components = app.get_components_of_type(Packages)
         for component in components:
-            managed_packages += component.packages
+            managed_packages += component.managed_packages()
 
     for package in packages:
         assert package in managed_packages

plinth/package.py

@@ -101,7 +101,8 @@ class Packages(app.FollowerComponent):
         IGNORE = 'ignore'  # Proceed as if there are no conflicts
         REMOVE = 'remove'  # Remove the packages before installing the app
 
-    def __init__(self, component_id: str, packages: list[str],
+    def __init__(self, component_id: str,
+                 packages: list[Union[str, PackageExpression]],
                  skip_recommends: bool = False,
                  conflicts: Optional[list[str]] = None,
                  conflicts_action: Optional[ConflictsAction] = None):
@@ -126,29 +127,50 @@ class Packages(app.FollowerComponent):
         super().__init__(component_id)
 
         self.component_id = component_id
-        self._packages = packages
+        self._packages = []
+        for package in packages:
+            if isinstance(package, str):
+                self._packages.append(Package(package))
+            else:
+                self._packages.append(package)
+
         self.skip_recommends = skip_recommends
         self.conflicts = conflicts
         self.conflicts_action = conflicts_action
 
     @property
-    def packages(self) -> list[str]:
-        """Return the list of packages managed by this component."""
+    def packages(self) -> list[Union[str, PackageExpression]]:
+        """Return the list of packages and package expressions managed by this
+        component."""
         return self._packages
 
+    def managed_packages(self) -> list[str]:
+        """Return the list of possible packages before resolving."""
+        managed_packages: list[str] = []
+        for package in self.packages:
+            managed_package = package.possible()
+            managed_packages.extend(managed_package)
+
+        return managed_packages
+
+    def resolve(self) -> list[str]:
+        """Return the resolved list of packages to install."""
+        return [package.actual() for package in self.packages]
+
     def setup(self, old_version):
         """Install the packages."""
         # TODO: Drop the need for setup helper.
         module_name = self.app.__module__
         module = sys.modules[module_name]
         helper = module.setup_helper
-        helper.install(self.packages, skip_recommends=self.skip_recommends)
+        helper.install(self.resolve(), skip_recommends=self.skip_recommends)
 
     def diagnose(self):
         """Run diagnostics and return results."""
         results = super().diagnose()
         cache = apt.Cache()
-        for package_name in self.packages:
+        # XXX: Needs to be able to handle missing packages.
+        for package_name in self.resolve():
             result = 'warning'
             latest_version = '?'
             if package_name in cache:
@@ -187,9 +209,12 @@ class Packages(app.FollowerComponent):
             return None
 
         # List of all packages from all Package components
-        cache = apt.Cache()
-        return any(package for package in self.packages
-                   if package not in cache)
+        try:
+            self.resolve()
+        except MissingPackageError:
+            return True
+
+        return False
 
 
 class PackageException(Exception):

plinth/tests/test_package.py

@@ -53,8 +53,8 @@ class TestPackageExpressions(unittest.TestCase):
 def test_packages_init():
     """Test initialization of packages component."""
     component = Packages('test-component', ['foo', 'bar'])
+    assert component.managed_packages() == ['foo', 'bar']
     assert component.component_id == 'test-component'
-    assert component.packages == ['foo', 'bar']
     assert not component.skip_recommends
     assert component.conflicts is None
     assert component.conflicts_action is None
@@ -65,12 +65,27 @@ def test_packages_init():
     component = Packages('test-component', [], skip_recommends=True,
                          conflicts=['conflict1', 'conflict2'],
                          conflicts_action=Packages.ConflictsAction.IGNORE)
-    assert component.packages == []
+    assert component.managed_packages() == []
     assert component.skip_recommends
     assert component.conflicts == ['conflict1', 'conflict2']
     assert component.conflicts_action == Packages.ConflictsAction.IGNORE
 
 
+def test_packages_resolve():
+    """Test resolving of package expressions."""
+    component = Packages('test-component', ['python3'])
+    assert component.resolve() == ['python3']
+
+    component = Packages('test-component',
+                         [Package('unknown-package') | Package('python3')])
+    assert component.resolve() == ['python3']
+
+    component = Packages('test-component', [], skip_recommends=True,
+                         conflicts=['conflict1', 'conflict2'],
+                         conflicts_action=Packages.ConflictsAction.IGNORE)
+    assert component.resolve() == []
+
+
 def test_packages_setup():
     """Test setting up packages component."""
 
@@ -78,22 +93,31 @@ def test_packages_setup():
         """Test app"""
         app_id = 'test-app'
 
-    component = Packages('test-component', ['foo1', 'bar1'])
+    component = Packages('test-component', ['python3', 'bash'])
     app = TestApp()
     app.add(component)
     setup_helper.reset_mock()
     app.setup(old_version=3)
     setup_helper.install.assert_has_calls(
-        [call(['foo1', 'bar1'], skip_recommends=False)])
+        [call(['python3', 'bash'], skip_recommends=False)])
 
-    component = Packages('test-component', ['foo2', 'bar2'],
+    component = Packages('test-component', ['bash', 'perl'],
                          skip_recommends=True)
     app = TestApp()
     app.add(component)
     setup_helper.reset_mock()
     app.setup(old_version=3)
     setup_helper.install.assert_has_calls(
-        [call(['foo2', 'bar2'], skip_recommends=True)])
+        [call(['bash', 'perl'], skip_recommends=True)])
+
+    component = Packages('test-component',
+                         [Package('python3') | Package('unknown-package')])
+    app = TestApp()
+    app.add(component)
+    setup_helper.reset_mock()
+    app.setup(old_version=3)
+    setup_helper.install.assert_has_calls(
+        [call(['python3'], skip_recommends=False)])
 
 
 @patch('apt.Cache')