Use application time zone when gets time as String.

activesupport/lib/active_support/testing/time_helpers.rb

@@ -156,6 +156,8 @@ def travel_to(date_or_time)
 
         if date_or_time.is_a?(Date) && !date_or_time.is_a?(DateTime)
           now = date_or_time.midnight.to_time
+        elsif date_or_time.is_a?(String)
+          now = Time.zone.parse(date_or_time)
         else
           now = date_or_time.to_time.change(usec: 0)
         end

activesupport/test/time_travel_test.rb

@@ -3,6 +3,7 @@
 require_relative "abstract_unit"
 require "active_support/core_ext/date_time"
 require "active_support/core_ext/numeric/time"
+require "active_support/core_ext/string/conversions"
 require_relative "time_zone_test_helpers"
 
 class TimeTravelTest < ActiveSupport::TestCase
@@ -84,6 +85,20 @@ def test_time_helper_travel_to_with_time_zone
     end
   end
 
+  def test_time_helper_travel_to_with_string_for_time_zone
+    with_env_tz "US/Eastern" do
+      with_tz_default ActiveSupport::TimeZone["UTC"] do
+        Time.stub(:now, Time.now) do
+          expected_time = Time.new(2004, 11, 24, 1, 4, 44)
+
+          travel_to "2004-11-24 01:04:44" do
+            assert_equal expected_time.to_s(:db), Time.zone.now.to_s(:db)
+          end
+        end
+      end
+    end
+  end
+
   def test_time_helper_travel_back
     Time.stub(:now, Time.now) do
       expected_time = Time.new(2004, 11, 24, 1, 4, 44)