You have to provide a delta to the assertion for Floats:

    Assert.assertEquals(expected, actual, delta)


While delta is the maximum difference (delta) between expected and actual for which both numbers are still considered equal.

    Assert.assertEquals(0.0012f, 0.0014f, 0.0002); // true
    Assert.assertEquals(0.0012f, 0.0014f, 0.0001); //false

A delta-value of 0.0f also works, so for old fashioned &quot;==&quot; compares (use with care!), you can write

    Assert.assertEquals(expected, actual, 0.0f);

instead of

    Assert.assertEquals(expected, actual); // Deprecated
    Assert.assertTrue(expected == actual); // Not JUnit

I like the way JUnit ensures that you really thought about the &quot;delta&quot; which should only be 0.0f in really trivial cases.

I have an ASP.Net c# project trying to access methods in a class in another project. It&#39;s working for first half of methods in the class but not for the other half of the methods in the class which I recently added. They compile, but they throw a method not found exception at run-time.

Does anyone have any ideas I could try? I&#39;ve tried:

 1. recreating the `.sln` file
 2. Subbing in another class library project, which I know works. It appears that the error is in my main project that calls the method in the other project.

Method not found on runtime

I find recursion, apart from very straight forward ones like factorial, very difficult to understand. The following snippet prints all permutations of a string. Can anyone help me understand it. What is the way to go about to understand recursion properly.

    void permute(char a[], int i, int n)
    {
       int j;
       if (i == n)
         cout &lt;&lt; a &lt;&lt; endl;
       else
       {
           for (j = i; j &lt;= n; j++)
           {
              swap(a[i], a[j]);    		 
              permute(a, i+1, n);
              swap(a[i], a[j]);
           }
       }
    } 
    
    int main()
    {
       char a[] = &quot;ABCD&quot;;
       permute(a, 0, 3);
       getchar();
       return 0;
    }

Understanding Recursion to generate permutations

I need to compare two values : one a string and the other is float
so I convert the string to float then try to call `assertEquals(val1,val2)` but this is not authorized , I guess that the `assertEquals` doesn&#39;t accept float as arguments.

What is the solution for me in this case ?

JUnit assertions : make the assertion between floats

<p>I need to compare two values : one a string and the other is float
so I convert the string to float then try to call <code>assertEquals(val1,val2)</code> but this is not authorized , I guess that the <code>assertEquals</code> doesn't accept float as arguments.</p>
<p>What is the solution for me in this case ?</p>


I have `&quot;Hello World&quot;` kept in a String variable named `hi`.

I need to print it, but reversed.

How can I do this? I understand there is some kind of a function already built-in into Java that does that.

Related: [Reverse each individual word of “Hello World” string with Java](https://stackoverflow.com/questions/2441501/reverse-hello-world-in-java)

Reverse a string in Java

I am new to Java testing with JUnit. I have to work with Java and I would like to use unit tests.

My problem is: I have an abstract class with some abstract methods. But there are some methods which are not abstract. How can I test this class with JUnit? Example code (very simple):

    abstract class Car {

        public Car(int speed, int fuel) {
            this.speed = speed;
            this.fuel = fuel;
        }

        private int speed;
        private int fuel;
    
        abstract void drive();
    
        public int getSpeed() {
            return this.speed;
        }
    
        public int getFuel() {
            return this.fuel;
        }
    }

I want to test `getSpeed()` and `getFuel()` functions.

Similar question to this problem is [here][2], but it is not using JUnit.

In JUnit FAQ section, I found [this link][3], but I don&#39;t understand what the author want to say with this example. What does this line of code mean?

    public abstract Source getSource() ;

  [1]: http://docs.python.org/library/unittest.html
  [2]: https://stackoverflow.com/questions/3604721/how-to-test-a-method-in-an-abstract-class-with-abstract-methods
  [3]: http://c2.com/cgi/wiki?AbstractTestCases

How to test abstract class in Java with JUnit?

What is the most efficient way to find the size of the intersection of two non-sparse Sets in Java? This is an operation I will be calling on large sets a very large number of times, so optimisation is important. I cannot modify the original sets.

I have looked at Apache Commons CollectionUtils.intersection which appears to be quite slow. My current approach is to take the smaller of the two sets, clone it, and then call .retainAll on the larger of the two sets.

    public static int getIntersection(Set&lt;Long&gt; set1, Set&lt;Long&gt; set2) {
        boolean set1IsLarger = set1.size() &gt; set2.size();
        Set&lt;Long&gt; cloneSet = new HashSet&lt;Long&gt;(set1IsLarger ? set2 : set1);
        cloneSet.retainAll(set1IsLarger ? set1 : set2);
        return cloneSet.size();
    }

Efficiently compute Intersection of two Sets in Java?

I have some Junit unit tests that require a large amount of heap-space to run - i.e. 1G. (They test memory-intensive functionality for a webstart app that will only run with sufficient heap-space, and will be run internally on Win 7 64-bit machines - so redesigning the tests isn&#39;t a practical suggestion.)

I am developing in Intellij IDEA, so I know I can set the JVM parameters (e.g. -Xmx1024M) for the test class. However, this is only for running the whole test class - if I want to run an individual test, I have to recreate the run congfigurations for that test method. 

Also, those are IDE and box specific - so if I switch boxes (I develop on multiple machines) or one of my colleagues tries to run the tests, those settings are not transferred. (Also, other IDEs like Eclipse and NetBeans are used by my colleagues.) FWIW, we&#39;re using mercurial for source code control.

For the build cycle, we&#39;re using Maven, so I know how to specify the JVM parameters for that.

So:
- I&#39;m looking for a way of specifying the JVM parameters that will apply for the whole test class and the individual test methods; and
- I&#39;d like to share those specification across IDEs on any machine (having picked up the code from the repository).

How to set JVM parameters for Junit Unit Tests?

According to Netbeans hint named **Use chain of .append methods instead of string concatenation**

&gt;Looks for string concatenation in the parameter of an invocation of the append method of StringBuilder or StringBuffer.

Is StringBuilder.append() really more efficient than strings concatenation?

Code sample

    StringBuilder sb = new StringBuilder();
    sb.append(filename + &quot;/&quot;);

vs.

    StringBuilder sb = new StringBuilder();
    sb.append(filename).append(&quot;/&quot;);

Is chain of StringBuilder.append more efficient than string concatenation?

I have a class which I would like to test with a public method that calls private one. I&#39;d like to assume that private method works correctly. For example, I&#39;d like something like `doReturn....when...`. I found that there is [possible solution using PowerMock](http://code.google.com/p/powermock/wiki/MockPrivate), but this solution doesn&#39;t work for me.
How It can be done? Did anybody have this problem?


How to mock private method for testing using PowerMock?

I&#39;m using JUnit-dep 4.10 and Hamcrest 1.3.RC2.

I&#39;ve created a custom matcher that looks like the following:

    public static class MyMatcher extends TypeSafeMatcher&lt;String&gt; {
        @Override
        protected boolean matchesSafely(String s) {
            /* implementation */
        }

        @Override
        public void describeTo(Description description) {
            /* implementation */
        }

        @Override
        protected void describeMismatchSafely(String item, Description mismatchDescription) {

            /* implementation */
        }
    }

It works perfectly fine when run from the command line using Ant.  But when run from IntelliJ, it fails with:

    java.lang.NoSuchMethodError: org.hamcrest.Matcher.describeMismatch(Ljava/lang/Object;Lorg/hamcrest/Description;)V
	    at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
	    at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:8)
	    at com.netflix.build.MyTest.testmyStuff(MyTest.java:40)

My guess is that it&#39;s using the wrong hamcrest.MatcherAssert.  How do I find which hamcrest.MatcherAssert it&#39;s using (ie which jar file it&#39;s using for hamcrest.MatcherAssert)?  AFAICT, the only hamcrest jars in my classpath is 1.3.RC2.

Is IntelliJ IDEA using it&#39;s own copy of JUnit or Hamcrest?

How do I output the runtime CLASSPATH that IntelliJ is using?

Getting &quot;NoSuchMethodError: org.hamcrest.Matcher.describeMismatch&quot; when running test in IntelliJ 10.5

I have a piece of Java code which uses an environment variable and the behaviour of the code depends on the value of this variable. I would like to test this code with different values of the environment variable. How can I do this in JUnit?

I&#39;ve seen [some ways to set environment variables in Java](https://stackoverflow.com/questions/318239/how-do-i-set-environment-variables-from-java) in general, but I&#39;m more interested in unit testing aspect of it, especially considering that tests shouldn&#39;t interfere with each other.

How to test code dependent on environment variables using JUnit?

What is the best way to count method invocations in a Unit Test. Do any of the testing frameworks allow that?



Counting method invocations in Unit tests

We&#39;ve a bunch of JUnit test cases (Integration tests) and they are logically grouped into different test classes.

We are able to load Spring application context once per test class and re-use it for all test cases in a JUnit test class as mentioned in http://static.springsource.org/spring/docs/current/spring-framework-reference/html/testing.html

However, we were just wondering if there is a way to load Spring application context only once for a bunch of JUnit test classes.

FWIW, we use Spring 3.0.5, JUnit 4.5 and use Maven to build the project.

Reuse spring application context across junit test classes

I read about [Structuring Unit Tests][1] with having a test class per class and an inner class per method. Figured that seemed like a handy way to organize the tests, so I tried it in our Java project. However, the tests in the inner classes doesn&#39;t seem to be picked up at all.

I did it roughly like this:

    public class DogTests
    {
        public class BarkTests
        {
            @Test
            public void quietBark_IsAtLeastAudible() { }
            
            @Test
            public void loudBark_ScaresAveragePerson() { }
        }
    
        public class EatTests
        {
            @Test
            public void normalFood_IsEaten() { }
    
            @Test
            public void badFood_ThrowsFit() { }
        }
    }

Does JUnit not support this, or am I just doing it wrong?


  [1]: http://haacked.com/archive/2012/01/02/structuring-unit-tests.aspx

Test cases in inner classes with JUnit

I have my existing framework built up using Jfunc which provides a facility to continue exection even when one of the asserts  in the test case fails. Jfunc uses junit 3.x framework. But now we are migrating to junit4 so I can&#39;t use Jfunc anymore and have replaced it with junit 4.10 jar. &lt;br&gt;
Now the problem is since we have extensively used jfunc in our framework, and with junit 4 we want to make our code continue the execution even when one of the asserts fails in a test case.&lt;br&gt;
Does anyone has any suggestion/idea for this, i know in junit the tests needs to be more atomic i.e. one assert per test case but we can&#39;t do that in our framework for some reason.

Content Type	Original Author	Original Content on Stackoverflow
Question	lola	View Question on Stackoverflow
Solution 1 - Java	oers	View Answer on Stackoverflow
Solution 2 - Java	RedXIII	View Answer on Stackoverflow

JUnit assertions : make the assertion between floats

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Understanding Recursion to generate permutations

Method not found on runtime

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