Make the dependency resolver respect the root package's python versions

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 
 - Dependencies of each package is now stored in `poetry.lock`.
 - Dependencies of each package is now stored in `poetry.lock`.
 - Improved TOML file management.
 - Improved TOML file management.
+- Dependency resolver now respects the root package python version requirements.
 
 
 ### Fixed
 ### Fixed
 
 

poetry.toml

@@ -3,7 +3,7 @@ name = "poetry"
 version = "0.2.0"
 version = "0.2.0"
 description = "Python dependency management and packaging made easy."
 description = "Python dependency management and packaging made easy."
 
 
-python-versions = ["^3.6"]
+python-versions = "^3.6"
 
 
 license = "MIT"
 license = "MIT"
 
 

poetry/installation/installer.py

@@ -126,12 +126,17 @@ class Installer:
                             Dependency(candidate.name, candidate.version)
                             Dependency(candidate.name, candidate.version)
                         )
                         )
 
 
-            solver = Solver(locked_repository, self._io)
+            solver = Solver(
+                self._package,
+                self._pool,
+                locked_repository,
+                self._io
+            )
 
 
             request = self._package.requires
             request = self._package.requires
             request += self._package.dev_requires
             request += self._package.dev_requires
 
 
-            ops = solver.solve(request, self._pool, fixed=fixed)
+            ops = solver.solve(request, fixed=fixed)
         else:
         else:
             self._io.writeln('<info>Installing dependencies from lock file</>')
             self._io.writeln('<info>Installing dependencies from lock file</>')
             if not self._locker.is_fresh():
             if not self._locker.is_fresh():

poetry/packages/dependency.py

+import poetry.packages
+
+from poetry.semver.constraints import Constraint
+from poetry.semver.constraints.base_constraint import BaseConstraint
 from poetry.semver.version_parser import VersionParser
 from poetry.semver.version_parser import VersionParser
 
 
 
 
 class Dependency:
 class Dependency:
 
 
-    def __init__(self, name, constraint, optional=False, category='main'):
+    def __init__(self,
+                 name: str,
+                 constraint: str,
+                 optional: bool = False,
+                 category: str = 'main',
+                 allows_prereleases: bool = False):
         self._name = name.lower()
         self._name = name.lower()
         self._pretty_name = name
         self._pretty_name = name
+        self._parser = VersionParser()
+
         try:
         try:
-            self._constraint = VersionParser().parse_constraints(constraint)
+            self._constraint = self._parser.parse_constraints(constraint)
         except ValueError:
         except ValueError:
-            self._constraint = VersionParser().parse_constraints('*')
+            self._constraint = self._parser.parse_constraints('*')
 
 
         self._pretty_constraint = constraint
         self._pretty_constraint = constraint
         self._optional = optional
         self._optional = optional
         self._category = category
         self._category = category
+        self._allows_prereleases = allows_prereleases
+
+        self._python_versions = '*'
+        self._python_constraint = self._parser.parse_constraints('*')
+        self._platform = '*'
+        self._platform_constraint = self._parser.parse_constraints('*')
 
 
     @property
     @property
     def name(self):
     def name(self):
@@ -35,8 +52,34 @@ class Dependency:
     def category(self):
     def category(self):
         return self._category
         return self._category
 
 
-    def accepts_prereleases(self):
-        return False
+    @property
+    def python_versions(self):
+        return self._python_versions
+
+    @python_versions.setter
+    def python_versions(self, value: str):
+        self._python_versions = value
+        self._python_constraint = self._parser.parse_constraints(value)
+
+    @property
+    def python_constraint(self):
+        return self._python_constraint
+
+    @property
+    def platform(self) -> str:
+        return self._platform
+
+    @platform.setter
+    def platform(self, value: str):
+        self._platform = value
+        self._platform_constraint = self._parser.parse_constraints(value)
+
+    @property
+    def platform_constraint(self):
+        return self._platform_constraint
+
+    def allows_prereleases(self):
+        return self._allows_prereleases
 
 
     def is_optional(self):
     def is_optional(self):
         return self._optional
         return self._optional
@@ -44,6 +87,16 @@ class Dependency:
     def is_vcs(self):
     def is_vcs(self):
         return False
         return False
 
 
+    def accepts(self, package: 'poetry.packages.Package') -> bool:
+        """
+        Determines if the given package matches this dependency.
+        """
+        return (
+            self._name == package.name
+            and self._constraint.matches(Constraint('=', package.version))
+            and (not package.is_prerelease() or self.allows_prereleases())
+        )
+
     def __eq__(self, other):
     def __eq__(self, other):
         if not isinstance(other, Dependency):
         if not isinstance(other, Dependency):
             return NotImplemented
             return NotImplemented

poetry/packages/locker.py

@@ -15,7 +15,7 @@ class Locker:
     _relevant_keys = [
     _relevant_keys = [
         'name',
         'name',
         'version',
         'version',
-        'python_versions',
+        'python-versions',
         'dependencies',
         'dependencies',
         'dev-dependencies',
         'dev-dependencies',
         'source',
         'source',

poetry/packages/package.py

+from poetry.semver.constraints.base_constraint import BaseConstraint
 from poetry.semver.helpers import parse_stability
 from poetry.semver.helpers import parse_stability
+from poetry.semver.version_parser import VersionParser
 
 
 from .dependency import Dependency
 from .dependency import Dependency
 from .vcs_dependency import VCSDependency
 from .vcs_dependency import VCSDependency
@@ -31,7 +33,7 @@ class Package:
         'dev': STABILITY_DEV,
         'dev': STABILITY_DEV,
     }
     }
 
 
-    def __init__(self, name, version, pretty_version):
+    def __init__(self, name, version, pretty_version=None):
         """
         """
         Creates a new in memory package.
         Creates a new in memory package.
 
 
@@ -48,7 +50,7 @@ class Package:
         self._name = name.lower()
         self._name = name.lower()
 
 
         self._version = version
         self._version = version
-        self._pretty_version = pretty_version
+        self._pretty_version = pretty_version or version
 
 
         self._description = ''
         self._description = ''
 
 
@@ -62,11 +64,16 @@ class Package:
         self.requires = []
         self.requires = []
         self.dev_requires = []
         self.dev_requires = []
 
 
+        self._parser = VersionParser()
+
         self.category = 'main'
         self.category = 'main'
         self.hashes = []
         self.hashes = []
         self.optional = False
         self.optional = False
-        self.python_versions = '*'
-        self.platform = '*'
+
+        self._python_versions = '*'
+        self._python_constraint = self._parser.parse_constraints('*')
+        self._platform = '*'
+        self._platform_constraint = self._parser.parse_constraints('*')
 
 
     @property
     @property
     def name(self):
     def name(self):
@@ -77,10 +84,6 @@ class Package:
         return self._pretty_name
         return self._pretty_name
 
 
     @property
     @property
-    def id(self):
-        return self._id
-
-    @property
     def version(self):
     def version(self):
         return self._version
         return self._version
 
 
@@ -112,6 +115,32 @@ class Package:
 
 
         return '{} {}'.format(self._pretty_version, self.source_reference)
         return '{} {}'.format(self._pretty_version, self.source_reference)
 
 
+    @property
+    def python_versions(self):
+        return self._python_versions
+
+    @python_versions.setter
+    def python_versions(self, value: str):
+        self._python_versions = value
+        self._python_constraint = self._parser.parse_constraints(value)
+
+    @property
+    def python_constraint(self):
+        return self._python_constraint
+
+    @property
+    def platform(self) -> str:
+        return self._platform
+
+    @platform.setter
+    def platform(self, value: str):
+        self._platform = value
+        self._platform_constraint = self._parser.parse_constraints(value)
+
+    @property
+    def platform_constraint(self):
+        return self._platform_constraint
+
     def is_dev(self):
     def is_dev(self):
         return self._dev
         return self._dev
 
 

poetry/poetry.py

@@ -63,8 +63,8 @@ class Poetry:
         version = normalize_version(pretty_version)
         version = normalize_version(pretty_version)
         package = Package(name, version, pretty_version)
         package = Package(name, version, pretty_version)
 
 
-        if 'python_versions' in package_config:
-            package.python_versions = package_config['python_versions']
+        if 'python-versions' in package_config:
+            package.python_versions = package_config['python-versions']
 
 
         if 'platform' in package_config:
         if 'platform' in package_config:
             package.platform = package_config['platform']
             package.platform = package_config['platform']

poetry/puzzle/provider.py

@@ -18,7 +18,6 @@ from poetry.packages import VCSDependency
 from poetry.repositories import Pool
 from poetry.repositories import Pool
 
 
 from poetry.semver import less_than
 from poetry.semver import less_than
-from poetry.semver.constraints import Constraint
 
 
 from poetry.utils.toml_file import TomlFile
 from poetry.utils.toml_file import TomlFile
 from poetry.utils.venv import Venv
 from poetry.utils.venv import Venv
@@ -30,8 +29,10 @@ class Provider(SpecificationProvider):
 
 
     UNSAFE_PACKAGES = {'setuptools', 'distribute', 'pip'}
     UNSAFE_PACKAGES = {'setuptools', 'distribute', 'pip'}
 
 
-    def __init__(self, pool: Pool):
+    def __init__(self, package: Package, pool: Pool):
+        self._package = package
         self._pool = pool
         self._pool = pool
+        self._python_constraint = package.python_constraint
 
 
     @property
     @property
     def pool(self) -> Pool:
     def pool(self) -> Pool:
@@ -168,13 +169,16 @@ class Provider(SpecificationProvider):
         if isinstance(requirement, Package):
         if isinstance(requirement, Package):
             return requirement == package
             return requirement == package
 
 
-        if package.is_prerelease() and not requirement.accepts_prereleases():
+        if not requirement.accepts(package):
+            return False
+
+        if package.is_prerelease() and not requirement.allows_prereleases():
             vertex = activated.vertex_named(package.name)
             vertex = activated.vertex_named(package.name)
 
 
-            if not any([r.accepts_prereleases() for r in vertex.requirements]):
+            if not any([r.allows_prereleases() for r in vertex.requirements]):
                 return False
                 return False
 
 
-        return requirement.constraint.matches(Constraint('==', package.version))
+        return self._package.python_constraint.matches(package.python_constraint)
 
 
     def sort_dependencies(self,
     def sort_dependencies(self,
                           dependencies: List[Dependency],
                           dependencies: List[Dependency],
@@ -182,7 +186,7 @@ class Provider(SpecificationProvider):
                           conflicts: Dict[str, List[Conflict]]):
                           conflicts: Dict[str, List[Conflict]]):
         return sorted(dependencies, key=lambda d: [
         return sorted(dependencies, key=lambda d: [
             0 if activated.vertex_named(d.name).payload else 1,
             0 if activated.vertex_named(d.name).payload else 1,
-            0 if d.accepts_prereleases() else 1,
+            0 if d.allows_prereleases() else 1,
             0 if d.name in conflicts else 1,
             0 if d.name in conflicts else 1,
             0 if activated.vertex_named(d.name).payload else len(self.search_for(d))
             0 if activated.vertex_named(d.name).payload else len(self.search_for(d))
         ])
         ])

poetry/puzzle/solver.py

@@ -16,12 +16,14 @@ from .ui import UI
 
 
 class Solver:
 class Solver:
 
 
-    def __init__(self, locked, io):
+    def __init__(self, package, pool, locked, io):
+        self._package = package
+        self._pool = pool
         self._locked = locked
         self._locked = locked
         self._io = io
         self._io = io
 
 
-    def solve(self, requested, pool, fixed=None) -> List[Operation]:
-        resolver = Resolver(Provider(pool), UI(self._io))
+    def solve(self, requested, fixed=None) -> List[Operation]:
+        resolver = Resolver(Provider(self._package, self._pool), UI(self._io))
 
 
         base = None
         base = None
         if fixed is not None:
         if fixed is not None:

poetry/semver/constraints/empty_constraint.py

@@ -9,4 +9,4 @@ class EmptyConstraint(BaseConstraint):
         return True
         return True
 
 
     def __str__(self):
     def __str__(self):
-        return '[]'
+        return '*'

poetry/semver/constraints/multi_constraint.py

@@ -36,6 +36,6 @@ class MultiConstraint(BaseConstraint):
         for constraint in self._constraints:
         for constraint in self._constraints:
             constraints.append(str(constraint))
             constraints.append(str(constraint))
 
 
-        return '[{}]'.format(
+        return '{}'.format(
             (' ' if self._conjunctive else ' || ').join(constraints)
             (' ' if self._conjunctive else ' || ').join(constraints)
         )
         )

tests/installation/fixtures/with-python-versions.test

+[[package]]
+name = "A"
+version = "1.0"
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[[package]]
+name = "B"
+version = "1.1"
+category = "main"
+optional = false
+python-versions = "*"
+platform = "*"
+
+[[package]]
+name = "C"
+version = "1.2"
+category = "main"
+optional = false
+python-versions = "^3.6"
+platform = "*"
+
+[metadata]
+python-versions = "^3.4"
+platform = "*"
+content-hash = "123456789"
+
+[metadata.hashes]
+A = []
+B = []
+C = []

tests/installation/test_installer.py

@@ -46,6 +46,8 @@ class Locker(BaseLocker):
     
     
     def _write_lock_data(self, data) -> None:
     def _write_lock_data(self, data) -> None:
         for package in data['package']:
         for package in data['package']:
+            package['python-versions'] = str(package['python-versions'])
+            package['platform'] = str(package['platform'])
             if not package['dependencies']:
             if not package['dependencies']:
                 del package['dependencies']
                 del package['dependencies']
 
 
@@ -214,3 +216,28 @@ def test_add_with_sub_dependencies(installer, locker, repo, package):
     expected = fixture('with-sub-dependencies')
     expected = fixture('with-sub-dependencies')
 
 
     assert locker.written_data == expected
     assert locker.written_data == expected
+
+
+def test_run_with_python_versions(installer, locker, repo, package):
+    package.python_versions = '^3.4'
+
+    package_a = get_package('A', '1.0')
+    package_b = get_package('B', '1.1')
+    package_c12 = get_package('C', '1.2')
+    package_c12.python_versions = '^3.6'
+    package_c13 = get_package('C', '1.3')
+    package_c13.python_versions = '~3.3'
+
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+    repo.add_package(package_c12)
+    repo.add_package(package_c13)
+
+    package.add_dependency('A', '~1.0')
+    package.add_dependency('B', '^1.0')
+    package.add_dependency('C', '^1.0')
+
+    installer.run()
+    expected = fixture('with-python-versions')
+
+    assert locker.written_data == expected

tests/mixology/index.py

@@ -72,7 +72,7 @@ class Index(SpecificationProvider):
         if package.is_prerelease() and not requirement.accepts_prereleases():
         if package.is_prerelease() and not requirement.accepts_prereleases():
             vertex = activated.vertex_named(package.name)
             vertex = activated.vertex_named(package.name)
 
 
-            if not any([r.accepts_prereleases() for r in vertex.requirements]):
+            if not any([r.allows_prereleases() for r in vertex.requirements]):
                 return False
                 return False
 
 
         return requirement.constraint.matches(Constraint('==', package.version))
         return requirement.constraint.matches(Constraint('==', package.version))
@@ -83,7 +83,7 @@ class Index(SpecificationProvider):
 
 
         results = []
         results = []
         for spec in self._packages[dependency.name]:
         for spec in self._packages[dependency.name]:
-            if not dependency.accepts_prereleases() and spec.is_prerelease():
+            if not dependency.allows_prereleases() and spec.is_prerelease():
                 continue
                 continue
 
 
             if dependency.constraint.matches(Constraint('==', spec.version)):
             if dependency.constraint.matches(Constraint('==', spec.version)):
@@ -103,7 +103,7 @@ class Index(SpecificationProvider):
                           conflicts):
                           conflicts):
         return sorted(dependencies, key=lambda d: [
         return sorted(dependencies, key=lambda d: [
             0 if activated.vertex_named(d.name).payload else 1,
             0 if activated.vertex_named(d.name).payload else 1,
-            0 if d.accepts_prereleases() else 1,
+            0 if d.allows_prereleases() else 1,
             0 if d.name in conflicts else 1,
             0 if d.name in conflicts else 1,
             0 if activated.vertex_named(d.name).payload else len(self.search_for(d))
             0 if activated.vertex_named(d.name).payload else len(self.search_for(d))
         ])
         ])

tests/packages/test_dependency.py

+from poetry.packages import Dependency
+from poetry.packages import Package
+
+
+def test_accepts():
+    dependency = Dependency('A', '^1.0')
+    package = Package('A', '1.4')
+
+    assert dependency.accepts(package)
+
+
+def test_accepts_prerelease():
+    dependency = Dependency('A', '^1.0', allows_prereleases=True)
+    package = Package('A', '1.4-beta.1')
+
+    assert dependency.accepts(package)
+
+
+def test_accepts_python_versions():
+    dependency = Dependency('A', '^1.0')
+    dependency.python_versions = '^3.6'
+    package = Package('A', '1.4')
+    package.python_versions = '~3.6'
+
+    assert dependency.accepts(package)
+
+
+def test_accepts_fails_with_different_names():
+    dependency = Dependency('A', '^1.0')
+    package = Package('B', '1.4')
+
+    assert not dependency.accepts(package)
+
+
+def test_accepts_fails_with_version_mismatch():
+    dependency = Dependency('A', '~1.0')
+    package = Package('B', '1.4')
+
+    assert not dependency.accepts(package)
+
+
+def test_accepts_fails_with_prerelease_mismatch():
+    dependency = Dependency('A', '^1.0')
+    package = Package('B', '1.4-beta.1')
+
+    assert not dependency.accepts(package)
+
+
+def test_accepts_fails_with_python_versions_mismatch():
+    dependency = Dependency('A', '^1.0')
+    dependency.python_versions = '^3.6'
+    package = Package('B', '1.4')
+    package.python_versions = '~3.5'
+
+    assert not dependency.accepts(package)

tests/puzzle/test_solver.py

@@ -3,7 +3,9 @@ import pytest
 from cleo.outputs.null_output import NullOutput
 from cleo.outputs.null_output import NullOutput
 from cleo.styles import OutputStyle
 from cleo.styles import OutputStyle
 
 
+from poetry.packages import Package
 from poetry.repositories.installed_repository import InstalledRepository
 from poetry.repositories.installed_repository import InstalledRepository
+from poetry.repositories.pool import Pool
 from poetry.repositories.repository import Repository
 from poetry.repositories.repository import Repository
 from poetry.puzzle import Solver
 from poetry.puzzle import Solver
 from poetry.puzzle.exceptions import SolverProblemError
 from poetry.puzzle.exceptions import SolverProblemError
@@ -18,13 +20,13 @@ def io():
 
 
 
 
 @pytest.fixture()
 @pytest.fixture()
-def installed():
-    return InstalledRepository()
+def package():
+    return Package('root', '1.0')
 
 
 
 
 @pytest.fixture()
 @pytest.fixture()
-def solver(installed, io):
-    return Solver(installed, io)
+def installed():
+    return InstalledRepository()
 
 
 
 
 @pytest.fixture()
 @pytest.fixture()
@@ -32,6 +34,16 @@ def repo():
     return Repository()
     return Repository()
 
 
 
 
+@pytest.fixture()
+def pool(repo):
+    return Pool([repo])
+
+
+@pytest.fixture()
+def solver(package, pool, installed, io):
+    return Solver(package, pool, installed, io)
+
+
 def check_solver_result(ops, expected):
 def check_solver_result(ops, expected):
     result = []
     result = []
     for op in ops:
     for op in ops:
@@ -58,18 +70,18 @@ def test_solver_install_single(solver, repo):
     package_a = get_package('A', '1.0')
     package_a = get_package('A', '1.0')
     repo.add_package(package_a)
     repo.add_package(package_a)
 
 
-    ops = solver.solve([get_dependency('A')], repo)
+    ops = solver.solve([get_dependency('A')])
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'install', 'package': package_a}
         {'job': 'install', 'package': package_a}
     ])
     ])
 
 
 
 
-def test_solver_remove_if_not_installed(solver, repo, installed):
+def test_solver_remove_if_not_installed(solver, installed):
     package_a = get_package('A', '1.0')
     package_a = get_package('A', '1.0')
     installed.add_package(package_a)
     installed.add_package(package_a)
 
 
-    ops = solver.solve([], repo)
+    ops = solver.solve([])
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'remove', 'package': package_a}
         {'job': 'remove', 'package': package_a}
@@ -80,8 +92,8 @@ def test_install_non_existing_package_fail(solver, repo):
     package_a = get_package('A', '1.0')
     package_a = get_package('A', '1.0')
     repo.add_package(package_a)
     repo.add_package(package_a)
 
 
-    with pytest.raises(SolverProblemError) as e:
-        solver.solve([get_dependency('B', '1')], repo)
+    with pytest.raises(SolverProblemError):
+        solver.solve([get_dependency('B', '1')])
 
 
 
 
 def test_solver_with_deps(solver, repo):
 def test_solver_with_deps(solver, repo):
@@ -95,7 +107,7 @@ def test_solver_with_deps(solver, repo):
 
 
     package_a.requires.append(get_dependency('B', '<1.1'))
     package_a.requires.append(get_dependency('B', '<1.1'))
 
 
-    ops = solver.solve([get_dependency('a')], repo)
+    ops = solver.solve([get_dependency('a')])
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'install', 'package': package_b},
         {'job': 'install', 'package': package_b},
@@ -118,7 +130,7 @@ def test_install_honours_not_equal(solver, repo):
 
 
     package_a.requires.append(get_dependency('B', '<=1.3,!=1.3,!=1.2'))
     package_a.requires.append(get_dependency('B', '<=1.3,!=1.3,!=1.2'))
 
 
-    ops = solver.solve([get_dependency('a')], repo)
+    ops = solver.solve([get_dependency('a')])
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'install', 'package': new_package_b11},
         {'job': 'install', 'package': new_package_b11},
@@ -145,7 +157,7 @@ def test_install_with_deps_in_order(solver, repo):
         get_dependency('C'),
         get_dependency('C'),
     ]
     ]
 
 
-    ops = solver.solve(request, repo)
+    ops = solver.solve(request)
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'install', 'package': package_c},
         {'job': 'install', 'package': package_c},
@@ -162,7 +174,7 @@ def test_install_installed(solver, repo, installed):
         get_dependency('A'),
         get_dependency('A'),
     ]
     ]
 
 
-    ops = solver.solve(request, repo)
+    ops = solver.solve(request)
 
 
     check_solver_result(ops, [])
     check_solver_result(ops, [])
 
 
@@ -179,7 +191,7 @@ def test_update_installed(solver, repo, installed):
         get_dependency('A'),
         get_dependency('A'),
     ]
     ]
 
 
-    ops = solver.solve(request, repo)
+    ops = solver.solve(request)
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'update', 'from': package_a, 'to': new_package_a}
         {'job': 'update', 'from': package_a, 'to': new_package_a}
@@ -198,7 +210,7 @@ def test_update_with_fixed(solver, repo, installed):
         get_dependency('A'),
         get_dependency('A'),
     ]
     ]
 
 
-    ops = solver.solve(request, repo, fixed=[get_dependency('A', '1.0')])
+    ops = solver.solve(request, fixed=[get_dependency('A', '1.0')])
 
 
     check_solver_result(ops, [])
     check_solver_result(ops, [])
 
 
@@ -218,7 +230,7 @@ def test_solver_sets_categories(solver, repo):
         get_dependency('B', category='dev')
         get_dependency('B', category='dev')
     ]
     ]
 
 
-    ops = solver.solve(request, repo)
+    ops = solver.solve(request)
 
 
     check_solver_result(ops, [
     check_solver_result(ops, [
         {'job': 'install', 'package': package_c},
         {'job': 'install', 'package': package_c},
@@ -229,3 +241,55 @@ def test_solver_sets_categories(solver, repo):
     assert package_c.category == 'dev'
     assert package_c.category == 'dev'
     assert package_b.category == 'dev'
     assert package_b.category == 'dev'
     assert package_a.category == 'main'
     assert package_a.category == 'main'
+
+
+def test_solver_respects_root_package_python_versions(solver, repo, package):
+    package.python_versions = '^3.4'
+    package_a = get_package('A', '1.0')
+    package_b = get_package('B', '1.0')
+    package_b.python_versions = '^3.6'
+    package_c = get_package('C', '1.0')
+    package_c.python_versions = '^3.6'
+    package_c11 = get_package('C', '1.1')
+    package_c11.python_versions = '~3.3'
+    package_b.add_dependency('C', '^1.0')
+
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+    repo.add_package(package_c)
+    repo.add_package(package_c11)
+
+    request = [
+        get_dependency('A'),
+        get_dependency('B')
+    ]
+
+    ops = solver.solve(request)
+
+    check_solver_result(ops, [
+        {'job': 'install', 'package': package_c},
+        {'job': 'install', 'package': package_b},
+        {'job': 'install', 'package': package_a},
+    ])
+
+
+def test_solver_fails_if_mismatch_root_python_versions(solver, repo, package):
+    package.python_versions = '^3.4'
+    package_a = get_package('A', '1.0')
+    package_b = get_package('B', '1.0')
+    package_b.python_versions = '^3.6'
+    package_c = get_package('C', '1.0')
+    package_c.python_versions = '~3.3'
+    package_b.add_dependency('C', '~1.0')
+
+    repo.add_package(package_a)
+    repo.add_package(package_b)
+    repo.add_package(package_c)
+
+    request = [
+        get_dependency('A'),
+        get_dependency('B')
+    ]
+
+    with pytest.raises(SolverProblemError):
+        solver.solve(request)