How to properly unit test a property change?

Question

I have this test: ``` @Test public void UpdateAllFooDatesToOneDayBeforeProvidedDate_TodaysDateAndFooDate_UpdatedDates() { // arrange List foos = new ArrayList(); Date barDate = today; Foo foo1 = setupFoo(); Foo foo2 = setupFoo(); foos.add(foo1); foos.add(foo2); foo1.setValidTo(dateUtil.adjustDaysOfDate(today, 5)); foo2.setValidTo(dateUtil.adjustDaysOfDate(today, 8)); // act modifyDates.updateAllFooDatesToOneDayBeforeProvidedDate(barDate, foos); // assert assertThat(foos, hasItems(...?)); //I don't know how to assert this } ``` updateAllFooDatesToOneDayBeforeProvidedDate(Date, List) simply changes a date property of all Foos to the day before barDate. I am trying to use Hamcrest to help me assert that the list has been updated, but I can't really get it to work. Should I simply use foos.get(n).getDate() and assert on those? What is the preferred way of asserting that the date property of the elements in foos has been updated properly? Edit: Typo

Accepted Answer

Aren't you making it hard on yourself here? Why not just iterate over the collection and assert for each element?

```
for ( Foo foo : foos ) { assertThat( foo.getDate() , equalTo( barDate ) ); }
```

Cheers,

How to properly unit test a property change?

Solution

Problem