Ensure setting dependency marker sets the python constraint

poetry/core/factory.py

@@ -238,6 +238,7 @@ def create_dependency(
         from .packages.url_dependency import URLDependency
         from .packages.utils.utils import create_nested_marker
         from .packages.vcs_dependency import VCSDependency
+        from .semver.helpers import parse_constraint
         from .version.markers import AnyMarker
         from .version.markers import parse_marker
 
@@ -340,11 +341,10 @@ def create_dependency(
             if not markers:
                 marker = AnyMarker()
                 if python_versions:
-                    dependency.python_versions = python_versions
                     marker = marker.intersect(
                         parse_marker(
                             create_nested_marker(
-                                "python_version", dependency.python_constraint
+                                "python_version", parse_constraint(python_versions)
                             )
                         )
                     )

poetry/core/packages/dependency.py

@@ -88,7 +88,7 @@ def __init__(
         self._activated = not self._optional
 
         self.is_root = False
-        self.marker = AnyMarker()
+        self._marker = AnyMarker()
         self.source_name = None
 
     @property
@@ -131,7 +131,7 @@ def python_versions(self, value: str) -> None:
         self._python_versions = value
         self._python_constraint = parse_constraint(value)
         if not self._python_constraint.is_any():
-            self.marker = self.marker.intersect(
+            self._marker = self._marker.intersect(
                 parse_marker(
                     self._create_nested_marker(
                         "python_version", self._python_constraint
@@ -151,6 +151,69 @@ def transitive_python_versions(self, value: str) -> None:
         self._transitive_python_versions = value
         self._transitive_python_constraint = parse_constraint(value)
 
+    @property
+    def marker(self) -> "BaseMarker":
+        return self._marker
+
+    @marker.setter
+    def marker(self, marker: Union[str, "BaseMarker"]) -> None:
+        from poetry.core.semver.helpers import parse_constraint
+        from poetry.core.version.markers import BaseMarker
+        from poetry.core.version.markers import parse_marker
+
+        from .utils.utils import convert_markers
+
+        if not isinstance(marker, BaseMarker):
+            marker = parse_marker(marker)
+
+        self._marker = marker
+
+        markers = convert_markers(marker)
+
+        if "extra" in markers:
+            # If we have extras, the dependency is optional
+            self.deactivate()
+
+            for or_ in markers["extra"]:
+                for _, extra in or_:
+                    self.in_extras.append(extra)
+
+        if "python_version" in markers:
+            ors = []
+            for or_ in markers["python_version"]:
+                ands = []
+                for op, version in or_:
+                    # Expand python version
+                    if op == "==" and "*" not in version:
+                        version = "~" + version
+                        op = ""
+                    elif op == "!=":
+                        version += ".*"
+                    elif op in ("in", "not in"):
+                        versions = []
+                        for v in re.split("[ ,]+", version):
+                            split = v.split(".")
+                            if len(split) in [1, 2]:
+                                split.append("*")
+                                op_ = "" if op == "in" else "!="
+                            else:
+                                op_ = "==" if op == "in" else "!="
+
+                            versions.append(op_ + ".".join(split))
+
+                        glue = " || " if op == "in" else ", "
+                        if versions:
+                            ands.append(glue.join(versions))
+
+                        continue
+
+                    ands.append("{}{}".format(op, version))
+
+                ors.append(" ".join(ands))
+
+            self._python_versions = " || ".join(ors)
+            self._python_constraint = parse_constraint(self._python_versions)
+
     @property
     def transitive_marker(self) -> "BaseMarker":
         if self._transitive_marker is None:
@@ -427,7 +490,6 @@ def create_from_pep_508(
 
         from .url_dependency import URLDependency
         from .utils.link import Link
-        from .utils.utils import convert_markers
         from .utils.utils import is_archive_file
         from .utils.utils import is_installable_dir
         from .utils.utils import is_url
@@ -446,11 +508,6 @@ def create_from_pep_508(
 
         req = Requirement(name)
 
-        if req.marker:
-            markers = convert_markers(req.marker)
-        else:
-            markers = {}
-
         name = req.name
         path = os.path.normpath(os.path.abspath(name))
         link = None
@@ -543,49 +600,6 @@ def create_from_pep_508(
 
             dep = Dependency(name, constraint, extras=req.extras)
 
-        if "extra" in markers:
-            # If we have extras, the dependency is optional
-            dep.deactivate()
-
-            for or_ in markers["extra"]:
-                for _, extra in or_:
-                    dep.in_extras.append(extra)
-
-        if "python_version" in markers:
-            ors = []
-            for or_ in markers["python_version"]:
-                ands = []
-                for op, version in or_:
-                    # Expand python version
-                    if op == "==" and "*" not in version:
-                        version = "~" + version
-                        op = ""
-                    elif op == "!=":
-                        version += ".*"
-                    elif op in ("in", "not in"):
-                        versions = []
-                        for v in re.split("[ ,]+", version):
-                            split = v.split(".")
-                            if len(split) in [1, 2]:
-                                split.append("*")
-                                op_ = "" if op == "in" else "!="
-                            else:
-                                op_ = "==" if op == "in" else "!="
-
-                            versions.append(op_ + ".".join(split))
-
-                        glue = " || " if op == "in" else ", "
-                        if versions:
-                            ands.append(glue.join(versions))
-
-                        continue
-
-                    ands.append("{}{}".format(op, version))
-
-                ors.append(" ".join(ands))
-
-            dep.python_versions = " || ".join(ors)
-
         if req.marker:
             dep.marker = req.marker
 

tests/packages/test_dependency.py

@@ -275,3 +275,11 @@ def test_with_constraint():
     assert new.transitive_marker == dependency.transitive_marker
     assert new.python_constraint == dependency.python_constraint
     assert new.transitive_python_constraint == dependency.transitive_python_constraint
+
+
+def test_marker_properly_sets_python_constraint():
+    dependency = Dependency("foo", "^1.2.3")
+
+    dependency.marker = 'python_version >= "3.6" and python_version < "4.0"'
+
+    assert str(dependency.python_constraint) == ">=3.6,<4.0"

tests/test_factory.py

@@ -68,7 +68,7 @@ def test_create_poetry():
 
     pathlib2 = dependencies["pathlib2"]
     assert pathlib2.pretty_constraint == "^2.2"
-    assert pathlib2.python_versions == "~2.7"
+    assert pathlib2.python_versions == ">=2.7 <2.8"
     assert not pathlib2.is_optional()
 
     demo = dependencies["demo"]
@@ -102,7 +102,7 @@ def test_create_poetry():
     dataclasses = dependencies["dataclasses"]
     assert dataclasses.name == "dataclasses"
     assert dataclasses.pretty_constraint == "^0.7"
-    assert dataclasses.python_versions == ">=3.6.1,<3.7"
+    assert dataclasses.python_versions == ">=3.6.1 <3.7"
     assert (
         str(dataclasses.marker)
         == 'python_full_version >= "3.6.1" and python_version < "3.7"'