Using regex with JUnit

Question

I've setup a unit test for a Java application that calls a web service. This web service returns a JSON string. Let's assume the following samples

{
"id": 2,
"time": "1346",
"user": {
    "firstname": "foo",
    "lastname": "bar",
    "email": "foo@bar.com"
  }
}

class GetUserImpl implements GetUser {
  public String getUserDetails() {
    return new MyWebService().getUserDetaild(];
  }
}

class Example Test {
  @Test
  public testGetUserDetails() {
    assertEquals(new GetUserImpl().getUserDetails(), regex);
  }
}

How would I use junit to test the following:

Is the ID a number, I don't care what the value is as long as it's not null and equal to or greater than 0
Is the time a valid format, regardless of the value
Is the email a valid email format, regardless of the value

I assume you own and not just use that web service, otherwise it wouldn't be your job to test the (hopefully stable) API. — beatngu13, Oct 22 '16 at 23:07
Correct, I own the web service. I guess another way to put it is this. I need to test the schema is as expected and a second test to make sure the format of the values are valid. — user316114, Oct 22 '16 at 23:36
I wouldnt use assertEquals here, but assertThat and probably a custom matcher. — GhostCat, Oct 23 '16 at 17:29

score 0 · Answer 1 · answered Oct 25 '16 at 17:17

Personally, I would prefer to break up your conditions into 3 different Assert statements and possible even 3 different tests and not try no lump all three requirements into one regex:

public void userIDShouldBeNonNullPositiveInteger()
public void userTimeShouldHaveValidTimeFormat()
public void userEmailShouldHaveValidFormat()

Also, agree with @GhostCat, that one good way to write these 3 tests is to have customMatchers for each. So, you could do something like this for the first test above:

public class PositiveIntegerMatcher extends TypeSafeDiagnosingMatcher<Integer> {
   @Override
   protected boolean matchesSafely(String idStr, Description description) {
       if (StringUtils.isNumeric(idStr) && isPositive(idStr) {
           return true;
       } else {
           return false;
       }
   }

   @Override
   public void describeTo(Description description) {

   }
}

This is some example code. Note, that I am using the apache commons (3) library to make things easy on myself, and I have not completed all of the code for you.

By breaking up this test into three tests, you will make your code much more readable and your intention clearer.

Using regex with JUnit

1 Answers1