Raise `TransactionTimeout` when lock wait timeout exceeded for PG adapter

Follow up of #30360.

activerecord/CHANGELOG.md

@@ -144,8 +144,8 @@
 
     *Jeremy Green*
 
-*   Add new error class `TransactionTimeout` for MySQL adapter which will be raised
-    when lock wait time expires.
+*   Add new error class `TransactionTimeout` which will be raised
+    when lock wait timeout exceeded.
 
     *Gabriel Courtemanche*
 

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -391,6 +391,7 @@ def default_index_type?(index) # :nodoc:
         UNIQUE_VIOLATION      = "23505"
         SERIALIZATION_FAILURE = "40001"
         DEADLOCK_DETECTED     = "40P01"
+        LOCK_NOT_AVAILABLE    = "55P03"
 
         def translate_exception(exception, message)
           return exception unless exception.respond_to?(:result)
@@ -410,6 +411,8 @@ def translate_exception(exception, message)
             SerializationFailure.new(message)
           when DEADLOCK_DETECTED
             Deadlocked.new(message)
+          when LOCK_NOT_AVAILABLE
+            TransactionTimeout.new(message)
           else
             super
           end

activerecord/test/cases/adapters/mysql2/transaction_test.rb

@@ -60,7 +60,7 @@ class Sample < ActiveRecord::Base
       end
     end
 
-    test "raises TransactionTimeout when mysql raises ER_LOCK_WAIT_TIMEOUT" do
+    test "raises TransactionTimeout when lock wait timeout exceeded" do
       assert_raises(ActiveRecord::TransactionTimeout) do
         s = Sample.create!(value: 1)
         latch1 = Concurrent::CountDownLatch.new

activerecord/test/cases/adapters/postgresql/transaction_test.rb

@@ -91,6 +91,35 @@ class Sample < ActiveRecord::Base
       end
     end
 
+    test "raises TransactionTimeout when lock wait timeout exceeded" do
+      skip unless ActiveRecord::Base.connection.postgresql_version >= 90300
+      assert_raises(ActiveRecord::TransactionTimeout) do
+        s = Sample.create!(value: 1)
+        latch1 = Concurrent::CountDownLatch.new
+        latch2 = Concurrent::CountDownLatch.new
+
+        thread = Thread.new do
+          Sample.transaction do
+            Sample.lock.find(s.id)
+            latch1.count_down
+            latch2.wait
+          end
+        end
+
+        begin
+          Sample.transaction do
+            latch1.wait
+            Sample.connection.execute("SET lock_timeout = 1")
+            Sample.lock.find(s.id)
+          end
+        ensure
+          Sample.connection.execute("SET lock_timeout = DEFAULT")
+          latch2.count_down
+          thread.join
+        end
+      end
+    end
+
     private
 
       def with_warning_suppression