many: extract lifecycle ordering into own module

snapcraft/cli/lifecycle.py

@@ -180,13 +180,16 @@ def clean(parts, step, **kwargs):
     """
     project_options = get_project_options(**kwargs)
     build_environment = env.BuilderEnvironmentConfig()
-    if build_environment.is_host:
-        step = step or steps.next_step(step).name
+
+    if step:
         if step == 'strip':
             echo.warning('DEPRECATED: Use `prime` instead of `strip` '
                          'as the step to clean')
-            step = steps.PRIME.name
-        lifecycle.clean(project_options, parts, steps.Step(step))
+            step = 'prime'
+        step = steps.get_step_by_name(step)
+
+    if build_environment.is_host:
+        lifecycle.clean(project_options, parts, step)
     else:
         config = project_loader.load_config(project_options)
         lxd.Project(project_options=project_options,

snapcraft/internal/errors.py

@@ -596,6 +596,13 @@ def __init__(self, path):
         super().__init__(path=path)
 
 
+class InvalidStepError(SnapcraftError):
+    fmt = "{step_name!r} is not a valid lifecycle step"
+
+    def __init__(self, step_name):
+        super().__init__(step_name=step_name)
+
+
 class NoLatestStepError(SnapcraftError):
     fmt = "The {part_name!r} part hasn't run any steps"
 

snapcraft/internal/lifecycle/_clean.py

@@ -100,8 +100,8 @@ def _cleanup_common_directories(config, project_options):
             if not max_step or step > max_step:
                     max_step = step
 
-    with contextlib.suppress(errors.NoNextStepError):
-        next_step = steps.next_step(max_step)
+    next_step = steps.next_step(max_step)
+    if next_step:
         _cleanup_common_directories_for_step(next_step, project_options)
 
 

snapcraft/internal/lifecycle/constants.py

@@ -15,6 +15,4 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import os
 
-from snapcraft.internal import steps
-
 SNAPCRAFT_INTERNAL_DIR = os.path.join('snap', '.snapcraft')

snapcraft/internal/lxd/_project.py

@@ -23,7 +23,6 @@
 from . import errors
 from ._containerbuild import Containerbuild
 from snapcraft.internal import lifecycle, steps
-from snapcraft.cli import echo
 
 logger = logging.getLogger(__name__)
 
@@ -103,7 +102,7 @@ def refresh(self):
             self._container_run(['apt-get', 'upgrade', '-y'])
             self._container_run(['snap', 'refresh'])
 
-    def clean(self, parts: List[str], step: str):
+    def clean(self, parts: List[str], step: steps.Step):
         # clean with no parts deletes the container
         if not step:
             if not parts:
@@ -112,10 +111,6 @@ def clean(self, parts: List[str], step: str):
                     print('Deleting {}'.format(self._container_name))
                     subprocess.check_call([
                         'lxc', 'delete', '-f', self._container_name])
-            step = steps.PULL.name
-        # clean normally, without involving the container
-        if step == 'strip':
-            echo.warning('DEPRECATED: Use `prime` instead of `strip` '
-                         'as the step to clean')
-            step = steps.PRIME.name
-        lifecycle.clean(self._project_options, parts, steps.Step(step))
+            step = steps.PULL
+
+        lifecycle.clean(self._project_options, parts, step)

snapcraft/internal/pluginhandler/__init__.py

@@ -226,7 +226,7 @@ def _migrate_state_file(self):
             if step:
                 os.remove(self.plugin.statedir)
                 os.makedirs(self.plugin.statedir)
-                self.mark_done(steps.Step(step))
+                self.mark_done(steps.get_step_by_name(step))
 
     def notify_part_progress(self, progress, hint=''):
         logger.info('%s %s %s', progress, self.name, hint)

snapcraft/internal/steps.py

@@ -16,6 +16,8 @@
 
 from typing import List
 
+from snapcraft.internal import errors
+
 
 class Step:
     def __init__(self, name: str, clean_if_dirty: bool) -> None:
@@ -26,7 +28,10 @@ def __init__(self, name: str, clean_if_dirty: bool) -> None:
     @property
     def _order(self) -> int:
         if self.__order is None:
-            self.__order = STEPS.index(self)
+            try:
+                self.__order = STEPS.index(self)
+            except ValueError:
+                raise errors.InvalidStepError(self.name)
         return self.__order
 
     def previous_step(self) -> 'Step':
@@ -96,7 +101,31 @@ def __repr__(self):
 
 
 def next_step(step):
+    """Get the next step of the lifecycle
+
+    :param Step step: The current step. If None, the next step is the first
+                      step in the lifecycle.
+    :return: The next step in the lifecycle
+    :rtype: Step
+    """
     if step:
         return step.next_step()
     else:
         return STEPS[0]
+
+
+def get_step_by_name(step_name):
+    """Get the lifecycle step that has the given name.
+
+    :param str step_name: Name of the step in question.
+    :return: The Step in the lifecycle that has the given name.
+    :rtype: Step
+    :raises: errors.InvalidStepError if there is no step with the given name.
+    """
+    if step_name:
+        for step in STEPS:
+            if step.name == step_name:
+                return step
+        raise errors.InvalidStepError(step_name)
+    else:
+        return STEPS[0]

tests/unit/__init__.py

@@ -170,8 +170,8 @@ def verify_state(self, part_name, state_dir, expected_step_name):
                         'Expected state directory for {}'.format(part_name))
 
         # Expect every step up to and including the specified one to be run
-        step = steps.Step(expected_step_name)
-        for step in step.previous_steps + [step]:
+        step = steps.get_step_by_name(expected_step_name)
+        for step in step.previous_steps() + [step]:
             self.assertTrue(os.path.exists(os.path.join(state_dir, step.name)),
                             'Expected {!r} to be run for {}'.format(
                                 step.name, part_name))

tests/unit/test_errors.py

@@ -498,6 +498,15 @@ class ErrorFormattingTestCase(unit.TestCase):
                 'Unable to parse mountinfo row: [1, 2, 3]'
             )
         }),
+        ('InvalidStepError', {
+            'exception': errors.InvalidStepError,
+            'kwargs': {
+                'step_name': 'test-step-name',
+            },
+            'expected_message': (
+                "'test-step-name' is not a valid lifecycle step"
+            )
+        }),
         ('NoLatestStepError', {
             'exception': errors.NoLatestStepError,
             'kwargs': {