From 3c0dac89e65475e97107adbb5c975ab7855d08db Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 20 Jan 2021 11:40:52 -0500
Subject: [PATCH] ensure downrev/dependencies in tuple form before using "in"

Fixed regression where new "loop detection" feature introduced in
:ticket:`757` produced false positives for revision names that have
overlapping substrings between revision number and down revision and/or
dependency, if the downrev/dependency were not in sequence form.

Fixes: #784
Change-Id: I9f31298c91ee2d3c1c63fd1f52bf8e0309b6ad88
---
 alembic/script/revision.py    |  6 ++++--
 docs/build/unreleased/784.rst |  8 ++++++++
 tests/test_revision.py        | 18 +++++++++++++++++-
 3 files changed, 29 insertions(+), 3 deletions(-)
 create mode 100644 docs/build/unreleased/784.rst

diff --git a/alembic/script/revision.py b/alembic/script/revision.py
index c75d1c0e..75249b4a 100644
--- a/alembic/script/revision.py
+++ b/alembic/script/revision.py
@@ -1037,9 +1037,11 @@ def verify_rev_id(cls, revision):
     def __init__(
         self, revision, down_revision, dependencies=None, branch_labels=None
     ):
-        if down_revision and revision in down_revision:
+        if down_revision and revision in util.to_tuple(down_revision):
             raise LoopDetected(revision)
-        elif dependencies is not None and revision in dependencies:
+        elif dependencies is not None and revision in util.to_tuple(
+            dependencies
+        ):
             raise DependencyLoopDetected(revision)
 
         self.verify_rev_id(revision)
diff --git a/docs/build/unreleased/784.rst b/docs/build/unreleased/784.rst
new file mode 100644
index 00000000..c85ba3c7
--- /dev/null
+++ b/docs/build/unreleased/784.rst
@@ -0,0 +1,8 @@
+.. change::
+    :tags: bug, versioning, regression
+    :tickets: 784
+
+    Fixed regression where new "loop detection" feature introduced in
+    :ticket:`757` produced false positives for revision names that have
+    overlapping substrings between revision number and down revision and/or
+    dependency, if the downrev/dependency were not in sequence form.
diff --git a/tests/test_revision.py b/tests/test_revision.py
index 767baa6e..3a6e9562 100644
--- a/tests/test_revision.py
+++ b/tests/test_revision.py
@@ -1288,7 +1288,7 @@ def _assert_raises_revision_map_dep_cycle(self, map_, revisions):
         )
 
 
-class GraphWithLoopTest(InvalidRevisionMapTest):
+class GraphWithLoopTest(DownIterateTest, InvalidRevisionMapTest):
     def test_revision_map_solitary_loop(self):
         map_ = RevisionMap(
             lambda: [
@@ -1297,6 +1297,22 @@ def test_revision_map_solitary_loop(self):
         )
         self._assert_raises_revision_map_loop(map_, "a")
 
+    def test_revision_map_no_loop_w_overlapping_substrings(self):
+        r1 = Revision("user_foo", None)
+        r2 = Revision("user", "user_foo")
+
+        self.map = RevisionMap(lambda: [r1, r2])
+
+        self._assert_iteration("heads", None, ["user", "user_foo"])
+
+    def test_revision_map_no_loop_w_overlapping_substrings_dependencies(self):
+        r1 = Revision("user_foo", None)
+        r2 = Revision("user", None, dependencies="user_foo")
+
+        self.map = RevisionMap(lambda: [r1, r2])
+
+        self._assert_iteration("heads", None, ["user", "user_foo"])
+
     def test_revision_map_base_loop(self):
         map_ = RevisionMap(
             lambda: [