Fix for "poetry lock --no-update" so that dependencies with extras are not…

Fix for "poetry lock --no-update" so that dependencies with extras are not updated unnecessarily (#4618)

* Fix for "poetry lock --no-update" so that dependencies with extras are not updated unnecessarily

* None check instead of "or"

* Simplified logic (giving up possibility of early return when no matching version is found)

* Rename local variable for clarity

src/poetry/mixology/version_solver.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import time
 
+from contextlib import suppress
 from typing import TYPE_CHECKING
 
 from poetry.core.packages.dependency import Dependency
@@ -365,12 +366,21 @@ class VersionSolver:
                 )
                 return dependency.complete_name
 
-            try:
-                version = packages[0]
-            except IndexError:
-                version = None
+            package = None
+            if dependency.name not in self._use_latest:
+                # prefer locked version of compatible (not exact same) dependency;
+                # required in order to not unnecessarily update dependencies with
+                # extras, e.g. "coverage" vs. "coverage[toml]"
+                locked = self._locked.get(dependency.name, None)
+            if locked is not None:
+                package = next(
+                    (p for p in packages if p.version == locked.version), None
+                )
+            if package is None:
+                with suppress(IndexError):
+                    package = packages[0]
 
-            if version is None:
+            if package is None:
                 # If there are no versions that satisfy the constraint,
                 # add an incompatibility that indicates that.
                 self._add_incompatibility(
@@ -379,12 +389,12 @@ class VersionSolver:
 
                 return dependency.complete_name
         else:
-            version = locked
+            package = locked
 
-        version = self._provider.complete_package(version)
+        package = self._provider.complete_package(package)
 
         conflict = False
-        for incompatibility in self._provider.incompatibilities_for(version):
+        for incompatibility in self._provider.incompatibilities_for(package):
             self._add_incompatibility(incompatibility)
 
             # If an incompatibility is already satisfied, then selecting version
@@ -399,9 +409,9 @@ class VersionSolver:
             )
 
         if not conflict:
-            self._solution.decide(version)
+            self._solution.decide(package)
             self._log(
-                f"selecting {version.complete_name} ({version.full_pretty_version})"
+                f"selecting {package.complete_name} ({package.full_pretty_version})"
             )
 
         return dependency.complete_name

tests/mixology/version_solver/test_with_lock.py

@@ -136,3 +136,35 @@ def test_with_compatible_locked_dependencies_use_latest(
         },
         use_latest=["foo"],
     )
+
+
+def test_with_compatible_locked_dependencies_with_extras(
+    root: ProjectPackage, provider: Provider, repo: Repository
+):
+    root.add_dependency(Factory.create_dependency("foo", "^1.0"))
+
+    package_foo_0 = get_package("foo", "1.0.0")
+    package_foo_1 = get_package("foo", "1.0.1")
+    bar_extra_dep = Factory.create_dependency(
+        "bar", {"version": "^1.0", "extras": "extra"}
+    )
+    for package_foo in (package_foo_0, package_foo_1):
+        package_foo.add_dependency(bar_extra_dep)
+        repo.add_package(package_foo)
+
+    bar_deps = {"baz": {"version": "^1.0", "extras": ["extra"]}}
+    add_to_repo(repo, "bar", "1.0.0", bar_deps)
+    add_to_repo(repo, "bar", "1.0.1", bar_deps)
+    add_to_repo(repo, "baz", "1.0.0")
+    add_to_repo(repo, "baz", "1.0.1")
+
+    check_solver_result(
+        root,
+        provider,
+        result={"foo": "1.0.0", "bar": "1.0.0", "baz": "1.0.0"},
+        locked={
+            "foo": get_package("foo", "1.0.0"),
+            "bar": get_package("bar", "1.0.0"),
+            "baz": get_package("baz", "1.0.0"),
+        },
+    )