rollback poetry.lock when a failure to add detected

src/poetry/console/commands/add.py

@@ -243,7 +243,7 @@ def handle(self) -> int:
 
         # Refresh the locker
         self.poetry.set_locker(
-            self.poetry.locker.__class__(self.poetry.locker.lock, poetry_content)
+            self.poetry.locker.copy_with(self.poetry.locker.lock, poetry_content)
         )
         self.installer.set_locker(self.poetry.locker)
 
@@ -261,9 +261,29 @@ def handle(self) -> int:
 
         status = self.installer.run()
 
-        if status == 0 and not self.option("dry-run"):
+        if self.option("dry-run"):
+            return status
+
+        if status == 0:
             assert isinstance(content, TOMLDocument)
             self.poetry.file.write(content)
+        else:
+            # rollback poetry.lock
+            for r in requirements:
+                section.remove(r["name"])
+                with contextlib.suppress(ValueError):
+                    self.poetry.package.dependency_group(group).remove_dependency(
+                        r["name"]
+                    )
+
+            self.poetry.set_locker(
+                self.poetry.locker.copy_with(self.poetry.locker.lock, poetry_content)
+            )
+            self.installer.set_locker(self.poetry.locker)
+
+            self.installer.lock(update=True)
+            self.installer.whitelist([])
+            self.installer.run()
 
         return status
 

src/poetry/packages/locker.py

@@ -267,6 +267,9 @@ def set_lock_data(self, root: Package, packages: list[Package]) -> bool:
             self._write_lock_data(lock)
         return do_write
 
+    def copy_with(self, lock: str | Path, local_config: dict[str, Any]) -> Locker:
+        return self.__class__(lock, local_config)
+
     def _write_lock_data(self, data: TOMLDocument) -> None:
         lockfile = TOMLFile(self.lock)
         lockfile.write(data)

tests/helpers.py

@@ -196,6 +196,12 @@ def __init__(self, lock: str | Path, local_config: dict) -> None:
         self._lock_data = None
         self._write = False
 
+    @property
+    def lock(self) -> Path:
+        if isinstance(self._lock, TOMLFile):
+            return self._lock.path
+        return self._lock
+
     def write(self, write: bool = True) -> None:
         self._write = write
 
@@ -215,6 +221,12 @@ def mock_lock_data(self, data: dict) -> None:
     def is_fresh(self) -> bool:
         return True
 
+    def copy_with(self, lock: str | Path, local_config: dict[str, Any]) -> TestLocker:
+        new_locker = TestLocker(lock, local_config)
+        new_locker._locked = self._locked
+        new_locker._write = self._write
+        return new_locker
+
     def _write_lock_data(self, data: TOMLDocument) -> None:
         if self._write:
             super()._write_lock_data(data)