[Demonstration 1]

[Buggy Method]
@Test
public void testFixedElementCounts() throws Exception {
    IsotopeFactory ifac = Isotopes.getInstance();
    IIsotope c = ifac.getMajorIsotope("C");
    IIsotope h = ifac.getMajorIsotope("H");
    IIsotope n = ifac.getMajorIsotope("N");
    IIsotope o = ifac.getMajorIsotope("O");
    MolecularFormulaRange mfRange = new MolecularFormulaRange();
    mfRange.addIsotope(c, 7, 7);
    mfRange.addIsotope(h, 15, 15);
    mfRange.addIsotope(o, 4, 4);
    mfRange.addIsotope(n, 2, 2);
    double massMin = 10d;
    double massMax = 1000d;
    MolecularFormulaGenerator gen = new MolecularFormulaGenerator(builder, massMin, massMax, mfRange);
    IMolecularFormulaSet mfSet = gen.getAllFormulas();
    Assert.assertNotNull(mfSet);
    Assert.assertEquals(mfSet.size(), 1);
    Assert.assertEquals("C7H15N2O4", MolecularFormulaManipulator.getString(mfSet.getMolecularFormula(0)));
}

[Buggy Hunk]
Assert.assertEquals(mfSet.size(), 1);

[Patch]
Assert.assertEquals(1, mfSet.size());