From 63f8a9af7800715772f9b03363888ea28486fcce Mon Sep 17 00:00:00 2001
From: Kevin McConnell <kevin@37signals.com>
Date: Wed, 12 Nov 2025 12:28:29 +0000
Subject: [PATCH] Deterministic fixture UUIDs

---
 app/models/account/seedeable.rb             |  2 +-
 app/models/concerns/uuid_primary_key.rb     | 52 +++++++++++++++++++++
 test/models/board/accessible_test.rb        |  2 +-
 test/models/notifier/event_notifier_test.rb |  2 +-
 test/test_helper.rb                         |  5 +-
 5 files changed, 58 insertions(+), 5 deletions(-)

diff --git a/app/models/account/seedeable.rb b/app/models/account/seedeable.rb
index cd8bea1fe..df33c2bab 100644
--- a/app/models/account/seedeable.rb
+++ b/app/models/account/seedeable.rb
@@ -2,6 +2,6 @@ module Account::Seedeable
   extend ActiveSupport::Concern
 
   def setup_customer_template
-    Account::Seeder.new(self, users.active.first).seed
+    Account::Seeder.new(self, users.active.order(created_at: :asc).first).seed
   end
 end
diff --git a/app/models/concerns/uuid_primary_key.rb b/app/models/concerns/uuid_primary_key.rb
index c905263ef..b990a63cd 100644
--- a/app/models/concerns/uuid_primary_key.rb
+++ b/app/models/concerns/uuid_primary_key.rb
@@ -10,6 +10,58 @@ module UuidPrimaryKey
     uuid_to_base36(SecureRandom.uuid_v7)
   end
 
+  def self.generate_fixture_uuid(label)
+    # Generate deterministic UUIDv7 for fixtures that sorts by fixture ID
+    # This allows .first/.last to work as expected in tests
+    fixture_int = Digest::MD5.hexdigest("fixtures#{label}").hex % (2**31)
+
+    # Use fixture_int as second offset from a fixed base time (1 year before 2025-01-01)
+    # This ensures all fixtures are in the past, and new test records are newest
+    base_time = Time.utc(2024, 1, 1, 0, 0, 0)
+    timestamp = base_time + fixture_int.seconds
+
+    uuid_v7_with_timestamp(timestamp, label)
+  end
+
+  def self.uuid_v7_with_timestamp(time, seed_string)
+    # Generate UUIDv7 with custom timestamp and deterministic random bits
+    # Format: 48-bit timestamp_ms | 12-bit random | 4-bit version | 62-bit random
+
+    timestamp_ms = (time.to_f * 1000).to_i
+
+    # 48-bit timestamp (milliseconds since epoch)
+    bytes = []
+    bytes[0] = (timestamp_ms >> 40) & 0xff
+    bytes[1] = (timestamp_ms >> 32) & 0xff
+    bytes[2] = (timestamp_ms >> 24) & 0xff
+    bytes[3] = (timestamp_ms >> 16) & 0xff
+    bytes[4] = (timestamp_ms >> 8) & 0xff
+    bytes[5] = timestamp_ms & 0xff
+
+    # Derive deterministic "random" bits from seed_string
+    hash = Digest::MD5.hexdigest(seed_string)
+
+    # 12-bit random + 4-bit version (0111 for v7)
+    rand_a = hash[0...3].to_i(16) & 0xfff
+    bytes[6] = ((rand_a >> 8) & 0x0f) | 0x70  # version 7
+    bytes[7] = rand_a & 0xff
+
+    # 2-bit variant (10) + 62-bit random
+    rand_b = hash[3...19].to_i(16) & ((2**62) - 1)
+    bytes[8] = ((rand_b >> 56) & 0x3f) | 0x80  # variant 10
+    bytes[9] = (rand_b >> 48) & 0xff
+    bytes[10] = (rand_b >> 40) & 0xff
+    bytes[11] = (rand_b >> 32) & 0xff
+    bytes[12] = (rand_b >> 24) & 0xff
+    bytes[13] = (rand_b >> 16) & 0xff
+    bytes[14] = (rand_b >> 8) & 0xff
+    bytes[15] = rand_b & 0xff
+
+    # Format as UUID string
+    uuid = "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x" % bytes
+    uuid_to_base36(uuid)
+  end
+
   def self.uuid_to_base36(uuid)
     # Convert standard UUID format to base36 (lowercase), padded to 25 chars
     uuid.delete('-').to_i(16).to_s(36).rjust(25, '0')
diff --git a/test/models/board/accessible_test.rb b/test/models/board/accessible_test.rb
index caae4e9b0..7677d51a5 100644
--- a/test/models/board/accessible_test.rb
+++ b/test/models/board/accessible_test.rb
@@ -5,7 +5,7 @@ class Board::AccessibleTest < ActiveSupport::TestCase
     boards(:writebook).update! all_access: false
 
     boards(:writebook).accesses.revise granted: users(:david, :jz), revoked: users(:kevin)
-    assert_equal users(:david, :jz), boards(:writebook).users
+    assert_equal users(:david, :jz).to_set, boards(:writebook).users.to_set
 
     boards(:writebook).accesses.grant_to users(:kevin)
     assert_includes boards(:writebook).users.reload, users(:kevin)
diff --git a/test/models/notifier/event_notifier_test.rb b/test/models/notifier/event_notifier_test.rb
index bc68b2a6c..1f2a6ff92 100644
--- a/test/models/notifier/event_notifier_test.rb
+++ b/test/models/notifier/event_notifier_test.rb
@@ -39,7 +39,7 @@ class Notifier::EventNotifierTest < ActiveSupport::TestCase
 
     Notifier.for(events(:logo_published)).notify
 
-    assert_equal cards(:logo), Notification.last.source.eventable
+    assert_equal cards(:logo), Notification.order(created_at: :desc).first.source.eventable
   end
 
   test "assignment events only create a notification for the assignee" do
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 64a149b63..90eab177e 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -80,8 +80,9 @@ module FixturesTestHelper
         label = label.to_s.delete_suffix("_uuid")
       end
 
-      return super(label, column_type) unless column_type == :uuid
-      UuidPrimaryKey.uuid_to_base36(super(label, column_type))
+      # Rails passes :string for varchar columns, so handle both :uuid and :string
+      return super(label, column_type) unless column_type.in?([:uuid, :string])
+      UuidPrimaryKey.generate_fixture_uuid(label)
     end
   end
 end