Add --splice support to merge command

alembic/command.py

@@ -385,6 +385,7 @@ def merge(
     message: Optional[str] = None,
     branch_label: Optional[_RevIdType] = None,
     rev_id: Optional[str] = None,
+    splice: bool = False,
 ) -> Optional[Script]:
     """Merge two revisions together.  Creates a new migration file.
 
@@ -435,6 +436,7 @@ def nothing(rev, context):
         refresh=True,
         head=revisions,
         branch_labels=branch_label,
+        splice=splice,
         **template_args,  # type:ignore[arg-type]
     )
 

alembic/config.py

@@ -737,7 +737,7 @@ def __init__(self, prog: Optional[str] = None) -> None:
             "--splice",
             dict(
                 action="store_true",
-                help="Allow a non-head revision as the 'head' to splice onto",
+                help="Allow using a non-head revision as a base by disabling head-only validation",
             ),
         ),
         "depends_on": (

tests/test_command.py

@@ -44,6 +44,7 @@
 from alembic.testing.fixtures import capture_engine_context_buffer
 from alembic.testing.fixtures import TestBase
 from alembic.util import compat
+from alembic.util import CommandError
 from alembic.util.sqla_compat import _connectable_has_table
 
 
@@ -276,6 +277,36 @@ def test_merge_cmd_revision_environment(self, rev_env):
 
         assert os.path.exists(rev.path)
 
+    def test_merge_cmd_with_splice(self):
+        cfg = self.cfg
+        self.a, self.b, self.c = three_rev_fixture(cfg)
+        self.d, self.e, self.f = multi_heads_fixture(
+            cfg, self.a, self.b, self.c
+        )
+        assert_raises(
+            CommandError,
+            command.merge,
+            cfg,
+            [self.a, self.b],
+            rev_id="merge_no_splice",
+            splice=False,
+        )
+        command.merge(
+            cfg,
+            [self.a, self.b],
+            rev_id="merge_with_splice",
+            splice=True,
+        )
+        script = ScriptDirectory.from_config(cfg).get_revision("merge_with_splice")
+        assert script is not None
+        assert os.path.exists(script.path)
+
+        with open(script.path, "r", encoding="utf-8") as fp:
+            contents = fp.read()
+
+        assert self.a in contents
+        assert self.b in contents
+
 
 class CurrentTest(_BufMixin, TestBase):
     @classmethod