Fix dependency resolution

poetry/mixology/contracts/specification_provider.py

@@ -36,7 +36,7 @@ class SpecificationProvider:
 
     def dependencies_for(self, specification: Any) -> List[Any]:
         """
-        Returns the dependencies of `specification`.
+        Returns the dependencies of specification.
         """
         return []
 

poetry/mixology/contracts/ui.py

@@ -26,7 +26,7 @@ class UI:
     def after_resolution(self) -> None:
         self.output.write('')
 
-    def debug(self, depth, message) -> None:
+    def debug(self, message, depth) -> None:
         if self.is_debugging():
             debug_info = str(message)
             debug_info = '\n'.join([

poetry/mixology/exceptions.py

@@ -44,7 +44,7 @@ class VersionConflict(ResolverError):
         for conflicting in flat_map(
             list(conflicts.values()), lambda x: x.requirements
         ):
-            for source, conflict_requirements in conflicting:
+            for source, conflict_requirements in conflicting.items():
                 for c in conflict_requirements:
                     pairs.append((c, source))
 

poetry/mixology/graph/add_edge_no_circular.py

@@ -50,7 +50,10 @@ class AddEdgeNoCircular(Action):
         """
         :type elements: list
         """
-        index = elements.index(element)
+        try:
+            index = elements.index(element)
+        except ValueError:
+            return
 
         if index != -1:
             elements.pop(index)

poetry/mixology/graph/add_vertex.py

 from .action import Action
 from .vertex import Vertex
 
+_NULL = object()
+
 
 class AddVertex(Action):
 
@@ -20,7 +22,7 @@ class AddVertex(Action):
         self._name = name
         self._payload = payload
         self._root = root
-        self._existing_payload = None
+        self._existing_payload = _NULL
         self._existing_root = None
 
     @property
@@ -56,7 +58,7 @@ class AddVertex(Action):
         return vertex
 
     def down(self, graph):
-        if self._existing_payload is not None:
+        if self._existing_payload is not _NULL:
             vertex = graph.vertices[self._name]
             vertex.payload = self._existing_payload
             vertex.root = self._existing_root

poetry/mixology/graph/delete_edge.py

@@ -50,7 +50,10 @@ class DeleteEdge(Action):
         """
         :type elements: list
         """
-        index = elements.index(element)
+        try:
+            index = elements.index(element)
+        except ValueError:
+            return
 
         if index != -1:
             elements.pop(index)

poetry/mixology/graph/vertex.py

@@ -62,7 +62,7 @@ class Vertex:
                 continue
 
             vertices.add(vertex)
-            vertex._recursive_predecessors(vertices)
+            vertex._recursive_successors(vertices)
 
         return vertices
 

poetry/mixology/possibility_set.py

@@ -11,3 +11,6 @@ class PossibilitySet:
 
     def __str__(self):
         return '[{}]'.format(', '.join([repr(p) for p in self.possibilities]))
+
+    def __repr__(self):
+        return f'<PossibilitySet {str(self)}>'

poetry/mixology/resolution.py

 import logging
 
 from copy import copy
-from time import time
+from datetime import datetime
 
 from typing import Any
 from typing import List
@@ -36,8 +36,10 @@ class Resolution:
         self._requested = requested
         self._original_requested = copy(requested)
         self._base = base
-        self._states = [ResolutionState.empty()]
+        self._states = []
         self._iteration_counter = 0
+        self._progress_rate = 0.33
+        self._iteration_rate = None
         self._parents_of = {}
         self._started_at = None
 
@@ -73,9 +75,14 @@ class Resolution:
                 if not self.state.requirement and not self.state.requirements:
                     break
 
-                # TODO: indicate progress
+                self._indicate_progress()
                 if hasattr(self.state, 'pop_possibility_state'):
-                    s = self.state.pop_possiblity_state()
+                    self._debug(
+                        f'Creating possibility state for '
+                        f'{str(self.state.requirement)} '
+                        f'({len(self.state.possibilities)} remaining)'
+                    )
+                    s = self.state.pop_possibility_state()
                     if s:
                         self._states.append(s)
                         self.activated.tag(s)
@@ -90,11 +97,14 @@ class Resolution:
         """
         Set up the resolution process.
         """
-        self._started_at = time()
+        self._started_at = datetime.now()
 
         self._handle_missing_or_push_dependency_state(self._initial_state())
 
-        logger.debug('Starting resolution')
+        self._debug(
+            f'Starting resolution ({self._started_at})\n'
+            f'Requested dependencies: {self._original_requested}'
+        )
 
         self._ui.before_resolution()
 
@@ -124,12 +134,13 @@ class Resolution:
         """
         Ends the resolution process
         """
+        elapsed = (datetime.now() - self._started_at).total_seconds()
+
         self._ui.after_resolution()
 
-        logger.debug(
-            'Finished resolution ({} steps) in {:.3f} seconds'.format(
-                self._iteration_counter, time() - self._started_at
-            )
+        self._debug(
+            f'Finished resolution ({self._iteration_counter} steps) '
+            f'in {elapsed:.3f} seconds'
         )
 
     def _process_topmost_state(self) -> None:
@@ -151,7 +162,8 @@ class Resolution:
         """
         The current possibility that the resolution is trying.
         """
-        return self.state.possibilities[-1]
+        if self.state.possibilities:
+            return self.state.possibilities[-1]
 
     @property
     def state(self) -> DependencyState:
@@ -213,17 +225,21 @@ class Resolution:
         unwind_options = self.state.unused_unwind_options
 
         self._debug(
-            self.state.depth,
             'Unwinding for conflict: '
             '{} to {}'.format(
-                self.state.requirement,
+                str(self.state.requirement),
                 details_for_unwind.state_index // 2
-            )
+            ),
+            self.state.depth
         )
 
         conflicts = self.state.conflicts
         sliced_states = self._states[details_for_unwind.state_index + 1:]
-        self._states = self._states[:details_for_unwind.state_index]
+        if details_for_unwind.state_index == -1:
+            self._states = []
+        else:
+            self._states = self._states[:details_for_unwind.state_index]
+
         self._raise_error_unless_state(conflicts)
         if sliced_states:
             self.activated.rewind_to(
@@ -251,7 +267,7 @@ class Resolution:
             return
 
         errors = [c.underlying_error
-                  for c in conflicts
+                  for c in conflicts.values()
                   if c.underlying_error is not None]
         if errors:
             error = errors[0]
@@ -484,12 +500,11 @@ class Resolution:
 
         return satisfied
 
-    def _filter_possibilities_for_parent_unwind(self, unwind_details):
+    def _filter_possibilities_for_parent_unwind(self,
+                                                unwind_details: UnwindDetails):
         """
         Filter a state's possibilities to remove any that would (eventually)
         the requirements in the conflict we've just rewound from.
-
-        :type unwind_details: UnwindDetails
         """
         unwinds_to_state = [
             uw
@@ -569,7 +584,10 @@ class Resolution:
         # If all the requirements together don't filter out all possibilities,
         # then the only two requirements we need to consider are the initial one
         # (where the dependency's version was first chosen) and the last
-        if self._binding_requirement_in_set(None, possible_binding_requirements, possibilities):
+        if self._binding_requirement_in_set(
+            None, possible_binding_requirements,
+            possibilities
+        ):
             return list(filter(None, [
                 conflict.requirement,
                 self._requirement_for_existing_name(
@@ -699,19 +717,29 @@ class Resolution:
 
         return tree
 
-    def _debug(self, depth, message):
-        self._ui.debug(depth, message)
+    def _indicate_progress(self):
+        self._iteration_counter += 1
+        progress_rate = self._ui.progress_rate or self._progress_rate
+        if self._iteration_rate is None:
+            if (datetime.now() - self._started_at).total_seconds() >= progress_rate:
+                self._iteration_rate = self._iteration_counter
+
+        if self._iteration_rate and (self._iteration_counter % self._iteration_rate) == 0:
+            self._ui.indicate_progress()
+
+    def _debug(self, message, depth=0):
+        self._ui.debug(message, depth)
 
     def _attempt_to_activate(self):
         self._debug(
+            f'Attempting to activate {str(self.possibility)}',
             self.state.depth,
-            'Attempting to activate {}'.format(self.possibility)
         )
         existing_vertex = self.activated.vertex_named(self.state.name)
         if existing_vertex.payload:
             self._debug(
-                self.state.depth,
-                'Found existing spec ({})'.format(existing_vertex.payload)
+                'Found existing spec ({})'.format(existing_vertex.payload),
+                self.state.depth
             )
             self._attempt_to_filter_existing_spec(existing_vertex)
         else:
@@ -747,6 +775,10 @@ class Resolution:
             self._push_state_for_requirements(new_requirements, False)
         else:
             self._create_conflict()
+            self._debug(
+                f'Unsatisfied by existing spec ({str(vertex.payload)})',
+                self.state.depth
+            )
             self._unwind_for_conflict()
 
     def _filtered_possibility_set(self, vertex):
@@ -770,13 +802,22 @@ class Resolution:
         if self.state.name in self.state.conflicts:
             del self.state.conflicts[self.name]
 
-        self.activated.set_payload(self.name, self.possibility)
+        self._debug(
+            f'Activated {self.state.name} at {str(self.possibility)}',
+            self.state.depth
+        )
+        self.activated.set_payload(self.state.name, self.possibility)
         self._require_nested_dependencies_for(self.possibility)
 
     def _require_nested_dependencies_for(self, possibility_set):
         nested_dependencies = self._provider.dependencies_for(
             possibility_set.latest_version
         )
+        self._debug(
+            f'Requiring nested dependencies '
+            f'({", ".join([str(d) for d in nested_dependencies])})',
+            self.state.depth
+        )
 
         for d in nested_dependencies:
             self.activated.add_child_vertex(

poetry/mixology/state.py

@@ -41,6 +41,9 @@ class ResolutionState:
     def empty(cls):
         return cls(None, [], DependencyGraph(), None, None, 0, {}, [])
 
+    def __repr__(self):
+        return f'<{self.__class__.__name__} {self._name}>'
+
 
 class PossibilityState(ResolutionState):
 
@@ -49,16 +52,16 @@ class PossibilityState(ResolutionState):
 
 class DependencyState(ResolutionState):
 
-    def pop_possiblity_state(self):
+    def pop_possibility_state(self):
         state = PossibilityState(
             self._name,
             copy(self._requirements),
             self._activated,
             self._requirement,
-            [self._possibilities.pop()],
+            [self.possibilities.pop() if self.possibilities else None],
             self._depth + 1,
-            copy(self._conflicts),
-            copy(self._unused_unwind_options)
+            copy(self.conflicts),
+            copy(self.unused_unwind_options)
         )
         state.activated.tag(state)
 

poetry/mixology/unwind_details.py

+from collections import namedtuple
+
+
 class UnwindDetails:
 
     def __init__(self,
@@ -37,10 +40,14 @@ class UnwindDetails:
         if self._sub_dependencies_to_avoid is None:
             self._sub_dependencies_to_avoid = []
             for tree in self.requirement_trees:
-                index = tree.index(self.state_requirement)
-                if index and tree[index + 1] is not None:
+                try:
+                    index = tree.index(self.state_requirement)
+                except ValueError:
+                    continue
+
+                if tree[index + 1] is not None:
                     self._sub_dependencies_to_avoid.append(tree[index + 1])
-                    
+
         return self._sub_dependencies_to_avoid
     
     @property
@@ -89,3 +96,6 @@ class UnwindDetails:
             return NotImplemented
 
         return self.state_index >= other.state_index
+
+    def __hash__(self):
+        return hash((id(self), self.state_index, self.state_requirement))

tests/mixology/fixtures/case/empty.json

+{
+  "name": "resolves an empty list of dependencies",
+  "requested": {
+  },
+  "base": [],
+  "resolved": [
+  ],
+  "conflicts": []
+}

tests/mixology/fixtures/case/unresolvable_child.json

+{
+  "name": "yields conflicts if a child dependency is not resolved",
+  "index": "unresolvable_child",
+  "requested": {
+    "chef_app_error": "*"
+  },
+  "base": [],
+  "resolved": [],
+  "conflicts": [
+    "json"
+  ]
+}

tests/mixology/fixtures/index/unresolvable_child.json

+{
+  "json": [
+    {
+      "name": "json",
+      "version": "1.8.0",
+      "dependencies": {
+      }
+    }
+  ],
+  "chef": [
+    {
+      "name": "chef",
+      "version": "10.26",
+      "dependencies": {
+        "json": "<= 1.7.7, >= 1.4.4"
+      }
+    }
+  ],
+  "berkshelf": [
+    {
+      "name": "berkshelf",
+      "version": "2.0.7",
+      "dependencies": {
+        "json": ">= 1.7.7"
+      }
+    }
+  ],
+  "chef_app_error": [
+    {
+      "name": "chef_app_error",
+      "version": "1.0.0",
+      "dependencies": {
+        "berkshelf": "~2.0",
+        "chef": "~10.26"
+      }
+    }
+  ]
+}

tests/mixology/test_resolver.py

@@ -4,7 +4,9 @@ import pytest
 
 from poetry.mixology import DependencyGraph
 from poetry.mixology import Resolver
+from poetry.mixology.exceptions import CircularDependencyError
 from poetry.mixology.exceptions import ResolverError
+from poetry.mixology.exceptions import VersionConflict
 from poetry.packages import Dependency
 
 from .index import Index
@@ -120,6 +122,7 @@ def assert_graph(dg, result):
 @pytest.mark.parametrize(
     'fixture',
     [
+        'empty',
         'simple',
         'simple_with_base',
         'simple_with_dependencies',
@@ -132,3 +135,27 @@ def test_resolver(fixture):
     dg = resolver.resolve(c.requested, base=c.base)
 
     assert_graph(dg, c.result)
+
+
+@pytest.mark.parametrize(
+    'fixture',
+    [
+        'circular',
+        'unresolvable_child'
+    ]
+)
+def test_resolver_fail(fixture):
+    c = case(fixture)
+    resolver = Resolver(c.index, UI())
+
+    with pytest.raises(ResolverError) as e:
+        resolver.resolve(c.requested, base=c.base)
+
+    names = []
+    e = e.value
+    if isinstance(e, CircularDependencyError):
+        names = [d.name for d in e.dependencies]
+    elif isinstance(e, VersionConflict):
+        names = [n for n in e.conflicts.keys()]
+
+    assert sorted(names) == sorted(c.conflicts)