JUnit Comparing Strings

Question

Doing some homework on JUnit. We have to test all our methods. I have the other 4 methods wrote out and testing correctly, but I am having trouble with the toString method not working like it should.

//here is my Gps constructor, if needed. I don't think it is, but including it just in case.

public Gps(String n, GpsCoordinates pos)
    {
        super();
        this.name = n;
        this.position = pos;
    }

//Here is my Gps.class toString() method that I want to test.
@Override
public String toString()
    {
        String gps = "myGPS: " + name + ": " + position;
        return gps;
    }

Here is my JUnit test method:

//Here are my instances in my GpsTest.class

private GpsCoordinates testGpsCoordinates = new GpsCoordinates(40.760671, -111.891122);
private Gps testGps3 = new Gps("TEST3", testGpsCoordinates);

//Here is my toString test method
    @Test
    public void testToString()
        {
            String expected = "myGPS: TEST3: 40.760671, -111.891122";
            assertEquals(expected, testGps3.toString());
        }

So when I run this, I get a JUnit failure. I check the logs and it says:

Expected:
myGPS: TEST3: 40.760671, -111.891122

Actual:
myGPS: TEST3: 40.760671, -111.891122

I thought maybe assertEquals uses "==" instead of .equals(), but that was not the case -- it DOES use .equals(), so I'm out of ideas

Can anyone point me in the right direction? I have been messing with this for 30 minutes now, moving around my instances, renaming things, etc. and am pulling my hair out.

cricket_007 asked that I add my GpsCoordinates.toString(), here it is:

public String toString()
{
    //formatting this to only return to 6 decimal places. On a separate part
    //of the assignment, we are to add a random double to the GpsCoordinates
    //(like a fake "gps update") and limit it to 6 decimal places.
    DecimalFormat df = new DecimalFormat("####.000000");
    return df.format(latitude) + ", " + df.format(longitude) + "\n";
}

@cricket_007 I added that to the original post. Do you think somehow my GpsCoordinates.toString() is getting called instead of Gps.toString()? — TaylorB
– TaylorB, Commented Feb 10, 2016 at 4:33
It is called when you do string concatenation with the position variable. That is why I asked. — OneCricketeer
– OneCricketeer, Commented Feb 10, 2016 at 4:35
@cricket_007 you're right, I'm dumb. 'position' belongs to GpsCoordinates, not Gps. Thank you Cricket! — TaylorB
– TaylorB, Commented Feb 10, 2016 at 4:36

Mateusz Mrozewski · Accepted Answer · 2016-02-10 04:33:16Z

4

Expected value does not have "\n" while GpsCoordinate.toString() adds it.

answered Feb 10, 2016 at 4:33

Mateusz Mrozewski

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Comments

Michael Anderson · Accepted Answer · 2016-02-10 04:33:48Z

2

So one thing that can cause this problem is unexpected trailing whitespace.

You've got a couple of options to handle that:

Running in eclipse or similar IDE may give you the option to get more information by double clicking on the failure. In eclipse you get a diff of the two strings for assertEquals failures - which shows the difference in a obvious way.
Add sentries to your strings before comparing: e.g.
```
assertEquals("'myGPS: TEST3: 40.760671, -111.891122'",
             "'" + testGps3.toString() +"'")
```
Any white-space differences should now be more obvious.

As Mateusz Mrozewski mentions you have an extra newline in your output. In this case the output for 2. will be

Expected:
'myGPS: TEST3: 40.760671, -111.891122'

Actual:
'myGPS: TEST3: 40.760671, -111.891122
'

And the issue is obvious.

answered Feb 10, 2016 at 4:33

Michael Anderson

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1 Comment

TaylorB Over a year ago

I was actually looking of a way to do this, so I will definitely be using this in the future. Thanks Michael.

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