feat: add --check flag to pdm lock (#1460)

news/1459.feature.md

@@ -0,0 +1 @@
+A new `pdm lock --check` flag to validate whether the lock is up to date.

src/pdm/cli/commands/lock.py

@@ -1,5 +1,7 @@
 import argparse
+import sys
 
+from pdm import termui
 from pdm.cli import actions
 from pdm.cli.commands.base import BaseCommand
 from pdm.cli.hooks import HookManager
@@ -23,7 +25,31 @@ def add_arguments(self, parser: argparse.ArgumentParser) -> None:
             help="Don't update pinned versions, only refresh the lock file",
         )
 
+        parser.add_argument(
+            "--check",
+            action="store_true",
+            help="Check if the lock file is up to date",
+        )
+
     def handle(self, project: Project, options: argparse.Namespace) -> None:
+        if options.check:
+            strategy = actions.check_lockfile(project, False)
+            if strategy:
+                project.core.ui.echo(
+                    f"[error]{termui.Emoji.FAIL}[/] Lockfile is [error]out of date[/].",
+                    err=True,
+                    verbosity=termui.Verbosity.DETAIL,
+                )
+                sys.exit(1)
+            else:
+                project.core.ui.echo(
+                    f"[success]{termui.Emoji.SUCC}[/] Lockfile is "
+                    "[success]up to date[/].",
+                    err=True,
+                    verbosity=termui.Verbosity.DETAIL,
+                )
+                sys.exit(0)
+
         actions.do_lock(
             project,
             refresh=options.refresh,

tests/cli/test_lock.py

@@ -60,6 +60,27 @@ def test_lock_refresh_keep_consistent(invoke, project, repository):
     assert project.lockfile_file.read_text() == previous
 
 
+def test_lock_check_no_change_success(invoke, project, repository):
+    project.add_dependencies({"requests": parse_requirement("requests")})
+    result = invoke(["lock"], obj=project)
+    assert result.exit_code == 0
+    assert project.is_lockfile_hash_match()
+
+    result = invoke(["lock", "--check"], obj=project)
+    assert result.exit_code == 0
+
+
+def test_lock_check_change_fails(invoke, project, repository):
+    project.add_dependencies({"requests": parse_requirement("requests")})
+    result = invoke(["lock"], obj=project)
+    assert result.exit_code == 0
+    assert project.is_lockfile_hash_match()
+
+    project.add_dependencies({"pyyaml": parse_requirement("pyyaml")})
+    result = invoke(["lock", "--check"], obj=project)
+    assert result.exit_code == 1
+
+
 @pytest.mark.usefixtures("repository")
 def test_innovations_with_specified_lockfile(invoke, project, working_set):
     project.add_dependencies({"requests": parse_requirement("requests")})