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IterableAssert.doesNotHaveDuplicates became unsable with many elements #122

thomas-hilaire opened this Issue Nov 6, 2012 · 1 comment


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I used fest in my projects at a snapshot version :
44bf124 FEST-258 : fix NPE that would occur if error stack trace filtering is enabled and we JUnit is not in the classpath

I encountered a performance issue with Fest 2.0M8 in *IterableAssert.doesNotHaveDuplicates method.
I made a small bench using a simple unit test to compare these versions :

Test :

public void testManyGeneration() {
    Stopwatch stopwatch = new Stopwatch().start();
    int generationCount = 10000;

    List<String> generated = Lists.newArrayListWithExpectedSize(generationCount);
    for (int count = 0; count < generationCount; count++) {

    System.out.println("Time elapsed in ms : " + stopwatch.stop().elapsedMillis());

Result :

version 2.0M8 :
10000 entries => Time elapsed in ms : 1907
100000 entries => Time elapsed in ms : 418619

version 44bf124 :
10000 entries => Time elapsed in ms : 198
100000 entries => Time elapsed in ms : 629

Can you improve the new version of doesNotHaveDuplicates method ?

Thanks for your library which is part of our DSL now, so appreciated !


joel-costigliola commented May 12, 2013

Just to let you know that this issue has been solved in AssertJ core in 1.2.0 release (AssertJ is a fork of Fest Assert). It is not yet solved in Fest (the previous github automatic comment may be confusing).


Joel Costigliola

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