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Java Unit Testing in Java What to Test The Happy Path and Beyond

Optional Message Paramater causing error

When I added the optional message parameter "proper row" and "proper column", I was not able to get the test to finish. I received the error "java: cannot access java.util.function.Supplier class file for java.util.function.Supplier not found

3 Answers

Mateusz Majewski
Mateusz Majewski
8,721 Points

Try this, it works for me in JUnit 5 (message is on the last place, not first):

assertEquals(1, loc.getRow(), "proper row");

assertEquals(3, loc.getColumn(), "proper column");

Michael Loria
Michael Loria
5,651 Points

Not an expert but I was having the same issue, I think one of the main differences is that I was using JUnit 5 Jupiter and its imports and Craig uses JUnit 4. Using the right imports and annotations helped fix the issue for me.

I think it will work if you use these imports ( which I think comes from JUnit 4) :

   import org.junit.Before;
   import org.junit.Test;
   import static org.junit.Assert.assertEquals;

Here is my code (with the annotations I also used) :

class AlphaNumericChooserTest {

 private AlphaNumericChooser chooser;

 void setUp() throws Exception {
     chooser = new AlphaNumericChooser(26, 10);

 void validInputReturnsProperLocation() throws Exception {
     AlphaNumericChooser.Location loc = chooser.locationFromInput("B4");

     assertEquals( "proper row" , 1, loc.getRow());
     assertEquals( "proper column" , 3, loc.getColumn());

Same. I was using JUnit 5 as well. But does that mean that optional message parameters are no longer used?

I'm a beginner and late for answering, but I hope this helps if someone gets here. I'm using JUnit 5 and optional message parameters seem to cause problems when running the tests, so I deleted them and found out that once you run the tests, the method which doesn't pass will be dotted underlined. So if I try with:

assertEquals(2, loc.getRow()); assertEquals(3, loc.getColumn());

the first method will be underlined.