Add option to create a solver test case

During the migration we may run into a situation where a package shows up
on the migrated system and we need to understand why this happened. Creating
a solver test case allows us to debug such issues.

doc/adoc/user_guide.adoc

@@ -3,13 +3,13 @@
 [#art-suse-migration-services]
 
 = Using the SUSE Distribution Migration System
-Marcus Schäfer; Jesús Velázquez; Keith Berger
+Marcus Schäfer; Jesús Velázquez; Keith Berger; Robert Schweikert
 
 :toc:
 :icons: font
 :numbered:
 
-:Authors: Marcus Schäfer, Jesús Bermúdez Velázquez, Keith Berger
+:Authors: Marcus Schäfer, Jesús Bermúdez Velázquez, Keith Berger, Robert Schweikert
 :Latest_Version: 1.2.0
 :Contributors:
 :Repo: https://github.com/SUSE/suse-migration-services[suse-migration-services]
@@ -312,7 +312,8 @@ verbose_migration: true|false
 
 Enable the fix option for pre_checks::
 If enabled (default), the run_pre_checks systemd process will use the `--fix`
-option to automatically remediate applicable issues before the migration is started. 
+option to automatically remediate applicable issues before the migration
+is started. 
 +
 [listing]
 ----
@@ -332,6 +333,18 @@ independent initrd can be created by setting
 build_host_independent_initrd: true|false
 ----
 
+Configure Dependency Solver Test Case Generation::
+It is possible that during the migration packages get installed that were not
+on the system previously and are pulled in because of dependencies. This
+setting will setup the migration such that a solver test case is generated.
+The information form the test case can then be used to understand why a
+given package was installed.
++
+[listing]
+----
+debug_solver: true|false
+----
+
 == Run the Migration
 Migration can be triggered either via run_migration or via reboot.
 

suse_migration_services/defaults.py

@@ -125,3 +125,7 @@ def get_proxy_path():
     @staticmethod
     def get_zypp_config_path():
         return '/etc/zypp/zypp.conf'
+
+    @staticmethod
+    def get_zypp_gen_solver_test_case():
+        return ''

suse_migration_services/migration_config.py

@@ -148,6 +148,9 @@ def get_migration_config_file_content(self):
     def is_verbosity_requested(self):
         return self.config_data.get('verbose_migration', False)
 
+    def is_zypp_solver_test_case_requested(self):
+        return self.config_data.get('debug_solver', False)
+
     def _write_config_file(self):
         with open(self.migration_config_file, 'w') as config:
             yaml.dump(self.config_data, config, default_flow_style=False)

suse_migration_services/schema.py

@@ -42,5 +42,9 @@
     'pre_checks_fix': {
         'required': False,
         'type': 'boolean'
+    },
+    'debug_solver': {
+        'required': False,
+        'type': 'boolean'
     }
 }

suse_migration_services/units/migrate.py

@@ -59,12 +59,18 @@ def main():
             log.info('Update env variables')
             update_env(migration_config.get_preserve_info())
             log_env(log)
-        verbose_migration = '--verbose' if migration_config.is_verbosity_requested() else '--no-verbose'
+        verbose_migration = '--no-verbose'
+        if migration_config.is_verbosity_requested():
+            verbose_migration = '--verbose'
+        solver_case = Defaults.get_zypp_gen_solver_test_case()
+        if migration_config.is_zypp_solver_test_case_requested():
+            solver_case = '--debug-solver'
         if migration_config.is_zypper_migration_plugin_requested():
             bash_command = ' '.join(
                 [
                     'zypper', 'migration',
                     verbose_migration,
+                    solver_case,
                     '--non-interactive',
                     '--gpg-auto-import-keys',
                     '--no-selfupdate',