add: fix revert for dry-run and interrupts

This change correctly reverts pyproject.toml changes for dry runs as 
well as keyboard interrupts.

Resolves: #2933 #318

poetry/console/commands/add.py

@@ -100,7 +100,6 @@ def handle(self):
  packages = [name for name in packages if name not in existing_packages]
 
  if not packages:
- self.poetry.file.write(content)
  self.line("Nothing to add.")
  return 0
 
@@ -152,29 +151,29 @@ def handle(self):
 
  poetry_content[section][_constraint["name"]] = constraint
 
- # Write new content
- self.poetry.file.write(content)
+ try:
+ # Write new content
+ self.poetry.file.write(content)
 
- # Cosmetic new line
- self.line("")
+  # Cosmetic new line
+  self.line("")
 
- # Update packages
- self.reset_poetry()
+  # Update packages
+  self.reset_poetry()
 
- self._installer.set_package(self.poetry.package)
- self._installer.dry_run(self.option("dry-run"))
- self._installer.verbose(self._io.is_verbose())
- self._installer.update(True)
- if self.option("lock"):
- self._installer.lock()
+  self._installer.set_package(self.poetry.package)
+  self._installer.dry_run(self.option("dry-run"))
+  self._installer.verbose(self._io.is_verbose())
+  self._installer.update(True)
+  if self.option("lock"):
+  self._installer.lock()
 
- self._installer.whitelist([r["name"] for r in requirements])
+  self._installer.whitelist([r["name"] for r in requirements])
 
- try:
  status = self._installer.run()
- except Exception:
+ except BaseException:
+ # Using BaseException here as some exceptions, eg: KeyboardInterrupt, do not inherit from Exception
  self.poetry.file.write(original_content)
-
  raise
 
  if status != 0 or self.option("dry-run"):

tests/console/commands/test_add.py

@@ -1630,3 +1630,26 @@ def test_add_with_lock_old_installer(app, repo, installer, old_tester):
 """
 
  assert expected == old_tester.io.fetch_output()
+
+
+def test_add_keyboard_interrupt_restore_content(app, repo, installer, tester, mocker):
+ mocker.patch(
+ "poetry.installation.installer.Installer.run", side_effect=KeyboardInterrupt()
+ )
+ original_content = app.poetry.file.read()
+
+ repo.add_package(get_package("cachy", "0.2.0"))
+
+ tester.execute("cachy --dry-run")
+
+ assert original_content == app.poetry.file.read()
+
+
+def test_dry_run_restore_original_content(app, repo, installer, tester):
+ original_content = app.poetry.file.read()
+
+ repo.add_package(get_package("cachy", "0.2.0"))
+
+ tester.execute("cachy --dry-run")
+
+ assert original_content == app.poetry.file.read()