still new to testing, how do I test this method:

[Dan Maples]

hey guys, I have a method that looks like this:

public double costanalysis(Sting item, double number){
   return item.length()*number;
}

I am trying to figure out the best way to run a test for it, any ideas? I am considering haveing a text file that I read with some strings and doubles in the text, would that be a good way to do it? Any other ways?
Thanks in advance, Dan

[Lasse Koskela]

What's wrong with

public class CostAnalysis {
    public double costanalysis(Sting item, double number){
        return item.length()*number;
    }
}
 
public class CostAnalysisTest extends TestCase {
 
    public void testCostAnalysis() throws Exception {
        CostAnalysis obj = new CostAnalysis();
        assertEquals(5.0d, obj.costanalysis("abcde", 1.0d), 0.000001d);
        assertEquals(2.0d, obj.costanalysis("abcde", 2.0d), 0.000001d);
        assertEquals(7.5d, obj.costanalysis("abcde", 1.5d), 0.000001d);
        assertEquals(1.0d, obj.costanalysis("a", 1.0d), 0.000001d);
        // and so forth...
    }
 
}

?

[Lasse Koskela]

Originally posted by Lasse Koskela:
What's wrong with

...

?

That is, except that one of the assertions fails

[Dan Maples]

Lasse, nothing is wrong with that, I was just wondering if there was anything special about testing strings and doubles. Also if I could get a loop in there it would be helpfull too Well I guess there is nothing special about this case then.

I also ran accross another problem I'm sure you can help me with. I can't get assertEquals() to work with doubles that are variable i.e.

assertEquals(expected,actual);

how can I get that to work?
Thanks for your help!
[ July 02, 2004: Message edited by: dan maples ]

[Lasse Koskela]

Also if I could get a loop in there it would be helpfull too

Sure you can. Using the suite() method:

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
 
public class CostAnalysisTest extends TestCase {
 
// populate the test data & expectation combinations into an array
// at class loading time
private static Object[][] TESTDATA;
static {
TESTDATA = new Object[][] {
{ "a", new Double(2.0d), new Double(2.0d) },
{ "ab", new Double(2.0d), new Double(4.0d) },
{ "ab", new Double(1.0d), new Double(2.0d) }
        };
}
 
public static Test suite() {
// create a test suite and fill it with "configured" instances of
// our TestCase class
TestSuite suite = new TestSuite();
for (int i = 0; i < TESTDATA.length; i++) {
String item = (String) TESTDATA[i][0];
double number = ((Double) TESTDATA[i][1]).doubleValue();
double expected = ((Double) TESTDATA[i][2]).doubleValue();
suite.addTest(new CostAnalysisTest(item, number, expected));
}
return suite;
}
 
private String item;
 
private double number;
 
private double expected;
 
public CostAnalysisTest(String item, double number, double expected) {
super("test"); // the test method's name
this.item = item;
this.number = number;
this.expected = expected;
}
 
// override the getName() method to get a nice, readable listing in
// Eclipse's JUnit GUI  :) 
public String getName() {
return "CostAnalysisTest: '" + item + "', " + number + ", " + expected;
}
 
// the actual test method
public void test() throws Exception {
CostAnalysis obj = new CostAnalysis();
assertEquals(expected, obj.costanalysis(item, number), 0.000001d);
}
 
}

I can't get assertEquals() to work with doubles that are variable i.e.

assertEquals(expected, actual);

how can I get that to work?

There is no assertEquals(double expected, double actual) but there is an assertEquals(double expected, double actual, double delta). See my earlier example of how you typically use it.
[ July 02, 2004: Message edited by: Lasse Koskela ]

[Dan Maples]

Thanks so much, you've been more than helpfull, but just one last thing I'm a little unsure about is:

assertEquals(double expected, double actual, double delta).

what is delta?
Thanks again-Dan

[Lasse Koskela]

"delta" is the acceptable deviation of the actual result from the expected result (double and float are approximations!). Typically the value for delta is something like 0.0000001d or 0.0000000001d or some other very small number...

[Dan Maples]

thank you so much, you've been so helpful, I really appreciate it.
-Dan