Improve enqueued_job at specs from #2350

Author: JonRowe

spec/rspec/rails/matchers/active_job_spec.rb

@@ -225,14 +225,25 @@ def self.name; "LoggingJob"; end
       }.to have_enqueued_job.at(time)
     end
 
-    skip_freeze_time = method_defined?(:freeze_time) ? false : "#freeze_time is undefined"
-    it "works with time offsets", skip: skip_freeze_time do
-      freeze_time do
-        time = Time.current
+    it "works with time offsets" do
+      # note that Time.current does not replicate Rails behavior for 5 seconds from now.
+      time = Time.current.change(usec: 0)
+      travel_to time do
         expect { hello_job.set(wait: 5).perform_later }.to have_enqueued_job.at(time + 5)
       end
     end
 
+    it "warns when time offsets are inprecise" do
+      expect(RSpec).to receive(:warn_with).with(/precision error/)
+
+      time = Time.current.change(usec: 550)
+      travel_to time do
+        expect {
+          expect { hello_job.set(wait: 5).perform_later }.to have_enqueued_job.at(time + 5)
+        }.to raise_error(/expected to enqueue exactly 1 jobs/)
+      end
+    end
+
     it "accepts composable matchers as an at date" do
       future = 1.minute.from_now
       slightly_earlier = 58.seconds.from_now