Compare Date objects with different levels of precision

Question

I have a JUnit test that fails because the milliseconds are different. In this case I don't care about the milliseconds. How can I change the precision of the assert to ignore milliseconds (or any precision I would like it set to)?

Example of a failing assert that I would like to pass:

Date dateOne = new Date(); dateOne.setTime(61202516585000L); Date dateTwo = new Date(); dateTwo.setTime(61202516585123L); assertEquals(dateOne, dateTwo); 

Answer 1

Yet another workaround, I'd do it like this:

assertTrue("Dates aren't close enough to each other!", (date2.getTime() - date1.getTime()) < 1000); 

Answer 2

There are libraries that help with this:

Apache commons-lang

If you have Apache commons-lang on your classpath, you can use DateUtils.truncate to truncate the dates to some field.

assertEquals(DateUtils.truncate(date1,Calendar.SECOND),              DateUtils.truncate(date2,Calendar.SECOND)); 

There is a shorthand for this:

assertTrue(DateUtils.truncatedEquals(date1,date2,Calendar.SECOND)); 

Note that 12:00:00.001 and 11:59:00.999 would truncate to different values, so this might not be ideal. For that, there is round:

assertEquals(DateUtils.round(date1,Calendar.SECOND),              DateUtils.round(date2,Calendar.SECOND)); 

AssertJ

Starting with version 3.7.0, AssertJ added an isCloseTo assertions, if you are using the Java 8 Date / Time API.

LocalTime _07_10 = LocalTime.of(7, 10); LocalTime _07_42 = LocalTime.of(7, 42); assertThat(_07_10).isCloseTo(_07_42, within(1, ChronoUnit.HOURS)); assertThat(_07_10).isCloseTo(_07_42, within(32, ChronoUnit.MINUTES)); 

It also works with legacy java Dates as well:

Date d1 = new Date(); Date d2 = new Date(); assertThat(d1).isCloseTo(d2, within(100, ChronoUnit.MILLIS).getValue());