Only write lock file when installation is success (#7498)

(affects `poetry add` and `poetry update`)

src/poetry/installation/installer.py

@@ -291,12 +291,10 @@ def _do_install(self) -> int:
         lockfile_repo = LockfileRepository()
         self._populate_lockfile_repo(lockfile_repo, ops)
 
-        if self._update:
+        if self._lock and self._update:
+            # If we are only in lock mode, no need to go any further
             self._write_lock_file(lockfile_repo)
-
-            if self._lock:
-                # If we are only in lock mode, no need to go any further
-                return 0
+            return 0
 
         if self._groups is not None:
             root = self._package.with_dependency_groups(list(self._groups), only=True)
@@ -362,7 +360,13 @@ def _do_install(self) -> int:
         self._filter_operations(ops, lockfile_repo)
 
         # Execute operations
-        return self._execute(ops)
+        status = self._execute(ops)
+
+        if status == 0 and self._update:
+            # Only write lock file when installation is success
+            self._write_lock_file(lockfile_repo)
+
+        return status
 
     def _write_lock_file(self, repo: LockfileRepository, force: bool = False) -> None:
         if self._write_lock and (force or self._update):

src/poetry/packages/locker.py

@@ -224,6 +224,18 @@ def locked_repository(self) -> LockfileRepository:
         return repository
 
     def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
+        """Store lock data and eventually persist to the lock file"""
+        lock = self._compute_lock_data(root, packages)
+
+        if self._should_write(lock):
+            self._write_lock_data(lock)
+            return True
+
+        return False
+
+    def _compute_lock_data(
+        self, root: Package, packages: list[Package]
+    ) -> TOMLDocument:
         package_specs = self._lock_packages(packages)
         # Retrieving hashes
         for package in package_specs:
@@ -254,6 +266,10 @@ def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
             "content-hash": self._content_hash,
         }
 
+        return lock
+
+    def _should_write(self, lock: TOMLDocument) -> bool:
+        # if lock file exists: compare with existing lock data
         do_write = True
         if self.is_locked():
             try:
@@ -263,8 +279,6 @@ def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
                 pass
             else:
                 do_write = lock != lock_data
-        if do_write:
-            self._write_lock_data(lock)
         return do_write
 
     def _write_lock_data(self, data: TOMLDocument) -> None:

tests/console/commands/self/test_add_plugins.py

@@ -49,11 +49,11 @@ def test_add_no_constraint(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 1 install, 0 updates, 0 removals
 
   • Installing poetry-plugin (0.1.0)
+
+Writing lock file
 """
     assert_plugin_add_result(tester, expected, "^0.1.0")
 
@@ -71,11 +71,11 @@ def test_add_with_constraint(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 1 install, 0 updates, 0 removals
 
   • Installing poetry-plugin (0.2.0)
+
+Writing lock file
 """
 
     assert_plugin_add_result(tester, expected, "^0.2.0")
@@ -93,12 +93,12 @@ def test_add_with_git_constraint(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (2.0.5)
   • Installing poetry-plugin (0.1.2 9cf87a2)
+
+Writing lock file
 """
 
     assert_plugin_add_result(
@@ -119,13 +119,13 @@ def test_add_with_git_constraint_with_extras(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 3 installs, 0 updates, 0 removals
 
   • Installing pendulum (2.0.5)
   • Installing tomlkit (0.7.0)
   • Installing poetry-plugin (0.1.2 9cf87a2)
+
+Writing lock file
 """
 
     assert_plugin_add_result(
@@ -162,12 +162,12 @@ def test_add_with_git_constraint_with_subdirectory(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 2 installs, 0 updates, 0 removals
 
   • Installing pendulum (2.0.5)
   • Installing poetry-plugin (0.1.2 9cf87a2)
+
+Writing lock file
 """
 
     constraint = {
@@ -262,11 +262,11 @@ def test_add_existing_plugin_updates_if_requested(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 0 installs, 1 update, 0 removals
 
   • Updating poetry-plugin (1.2.3 -> 2.3.4)
+
+Writing lock file
 """
 
     assert_plugin_add_result(tester, expected, "^2.3.4")
@@ -298,12 +298,12 @@ def test_adding_a_plugin_can_update_poetry_dependencies_if_needed(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 1 install, 1 update, 0 removals
 
   • Updating tomlkit (0.7.1 -> 0.7.2)
   • Installing poetry-plugin (1.2.3)
+
+Writing lock file
 """
 
     assert_plugin_add_result(tester, expected, "^1.2.3")

tests/console/commands/self/test_remove_plugins.py

@@ -73,11 +73,11 @@ def test_remove_installed_package(tester: CommandTester):
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 0 installs, 0 updates, 1 removal
 
   • Removing poetry-plugin (1.2.3)
+
+Writing lock file
 """
     assert tester.io.fetch_output() == expected
 

tests/console/commands/self/test_update.py

@@ -71,12 +71,12 @@ def test_self_update_can_update_from_recommended_installation(
 Updating dependencies
 Resolving dependencies...
 
-Writing lock file
-
 Package operations: 0 installs, 2 updates, 0 removals
 
   • Updating cleo (0.8.2 -> 1.0.0)
   • Updating poetry ({__version__} -> {new_version})
+
+Writing lock file
 """
 
     assert tester.io.fetch_output() == expected_output