This good thing was so small that I almost did not bother to blog it

But the devil is in the detail so here it is anyway.

I have this multi threaded application. One of the problems with integration testing it is, you can’t guarantee the order that messages will be written to a stream. So during the test I have to go to some trouble to split and order the lines written out. If I don’t do this the test fails sometimes. It depends on which thread writes first. The output though is correct, order is not important. Not exactly rocket science.

Here is the method I was using to massage the string.

 public List<String> getSortedLines(String expectedString) {

        String[] splitExpectedResultLines = expectedString.toString().split("\n");
        List<String> resultLines = new ArrayList<String>();
        for (String messageLine : resultLines) {
            resultLines.add(messageLine);
        }

        Collections.sort(resultLines);
        return resultLines;
    }

There is nothing particularly wrong with the method. It takes a string, splits it into lines, loads a List, sorts and returns it. Thus when its used in an assertion later the expected and actual lists are the same.

With google collections its just three lines! The HashMultiset is designed to be used in equals methods. Its equal even if the order of the elements in collections being compared is different. From the API documentation: An extension of Collection that may contain duplicate values like a List, yet has order-independent equality like a Set. One typical use for a multiset is to represent a histogram.

Its possible to use the HashMultiSet.create static factory method, passing in an Iterable. i.e a Collection. So from the original code, both the loop and the Collections.sort are no longer required.

   public HashMultiset<String> getOrderAgnosticCollection(String expectedString) {

        String[] splitExpectedResultLines = expectedString.toString().split("\n");
        Iterable<String> resultLines = Arrays.asList(splitExpectedResultLines);
        HashMultiset<String> orderAgnosticResultLines =
                                              HashMultiset.create(resultLines);

        return orderAgnosticResultLines;
    }

If there was something that performed the split, but returned an Iterable the method would be perfect!