Address pstodulk and abadger's comments

Raise exception if requested source_version or component
is not found with possible choices listed.

repos/system_upgrade/common/libraries/rpms.py

@@ -156,6 +156,7 @@ def get_leapp_packages(source_version=None, component=None, include_deps=False):
     :param component: a list or string specifying leapp components. If defined then only packages related
         to the specific component will be returned.
     :param include_deps: a flag to control whether deps meta packages are to be filtered out.
+    :raises ValueError: if a requested component or source_version doesn't exist.
     """
     res = set()
     source_versions = [source_version] if isinstance(source_version, str) else source_version
@@ -169,13 +170,16 @@ def get_leapp_packages(source_version=None, component=None, include_deps=False):
         components = _LEAPP_DEFAULT_COMPONENTS
     for comp in components:
         for src_version in source_versions:
-            try:
-                res.update(_LEAPP_PACKAGES_MAP[comp][src_version].get('pkgs', []))
-                if include_deps:
-                    res.update(_LEAPP_PACKAGES_MAP[comp][src_version].get('deps', []))
-            except KeyError:
-                stdlib.api.current_logger().warning(
-                        "The requested component {comp} or source_version {ver} is unknown".format(
-                            comp=component, ver=src_version))
-                continue
+            if comp not in _LEAPP_PACKAGES_MAP:
+                error_msg = "The requested component {comp} is unknown, available choices are {choices}".format(
+                        comp=component, choices=sorted(_LEAPP_PACKAGES_MAP.keys()))
+                raise ValueError(error_msg)
+            if src_version not in _LEAPP_PACKAGES_MAP[comp]:
+                error_msg = "The requested source_version {ver} is unknown, available choices are {choices}".format(
+                        ver=src_version, choices=sorted(_LEAPP_PACKAGES_MAP[comp].keys()))
+                raise ValueError(error_msg)
+            # All went well otherwise, get the data
+            res.update(_LEAPP_PACKAGES_MAP[comp][src_version].get('pkgs', []))
+            if include_deps:
+                res.update(_LEAPP_PACKAGES_MAP[comp][src_version].get('deps', []))
     return sorted(res)

repos/system_upgrade/common/libraries/tests/test_rpms.py

@@ -43,11 +43,21 @@ def test_parse_config_modification():
    ('7', None, False, ['leapp', 'python2-leapp', 'leapp-upgrade-el7toel8', 'snactor']),
    (['7', '8'], None, False, ['leapp', 'python2-leapp', 'leapp-upgrade-el7toel8',
                               'python3-leapp', 'leapp-upgrade-el8toel9', 'snactor']),
-   ('nosuchversion', None, False, []),
+   ('nosuchversion', None, False, 
+    (ValueError, r"source_version nosuchversion is unknown, available choices are \['7', '8']")),
    ('8', 'framework', False, ['leapp', 'python3-leapp']),
    ('8', 'framework', True, ['leapp', 'python3-leapp', 'leapp-deps']),
-   ('8', 'nosuchcomponent', True, []),
+   ('8', 'nosuchcomponent', True, 
+    (ValueError,
+     r"component nosuchcomponent is unknown, available choices are \['cockpit', 'framework', 'repository', 'tools']")),
    ])
 def test_get_leapp_packages(source_version, component, include_deps, result, monkeypatch):
     monkeypatch.setattr(api, 'current_actor', CurrentActorMocked(arch='x86_64', src_ver='8.9', dst_ver='9.3'))
-    assert set(get_leapp_packages(source_version, component, include_deps)) == set(result)
+    if isinstance(result, list):
+        assert set(get_leapp_packages(source_version, component, include_deps)) == set(result)
+    else:
+        # expect an exception tuple
+        exc_type, exc_msg = result
+        with pytest.raises(exc_type) as err:
+            get_leapp_packages(source_version, component, include_deps)
+        assert err.match(exc_msg)