FitNesse. UserGuide. FitLibraryUserGuide.
CombinationFixture [add child]
CombinationFixture is a specialised fixture for showing how pairs of values are expected to be combined. For example, here's a times table:

fitlibrary.specify.TimesCombination
  1 2 3
1 1 2 3
2 2 4 6
3 3 6 9

The fixture for this is as follows:

public class TimesCombination extends CombinationFixture {
public int combine(int x, int y) {
return x * y;
}
}


The method combine() is called for each pair of values, and the result checked. For example, for the cell in the last row above containing an expected value of 6, the method is called with the arguments combine(3,2).

In general, as usual:

fitlibrary.specify.DirectCombination
  1 2 3
100 100 200 300
220 220 440 660
330 330 660 990

The fixture for this class is as follows:

public class DirectCombination extends CombinationFixture {
public DirectCombination() {
super(new TimesCombination());
}
}


It just happens to refer to an object that is also a fixture.