Generate every combination of possible values for some set of parameters.
In testing it is sometimes of value to map out what the different parameters are for a particular feature or block of code, and then generating the full list of every distinct combination.
This is typically accomplished by writing a bunch of nested for loops. For speed, those loops skip invalid combinations as soon as possible, so that we don't waste time generating hundreds if not thousands of invalid sub-combinations, only to throw them away.
This module exists to abstract away this process, so that a GUI can be built to make it easier.
npm install --save combinatorial-eval
Generate all possible combinations
import { CombinatorialEval } from 'combinatorial-eval';
let callback = (o) => { console.log( o ); };
new CombinatorialEval()
.dimension( 'letter', ['A','B','C'] )
.dimension( 'digit', ['1','2','3'] )
.dimension( 'symbol' ['!','@','#'] )
.generate( callback );
// outputs 27 ( 3*3*3 ) objects, one for each combination
// in order: A1!, A1@, A!#, A2!, A2@, A2#, A3!, A3@, A3#, B1!, ...
Process each dimension in a random order
new CombinatorialEval()
.dimension( 'letter', "ABCDEFGHIJKLMNOPQRUSTUVWXYZ".split('') )
.shuffle()
.generate( callback );
// outputs one item per letter, but in random order
Apply a validation filter
new CombinatorialEval()
.dimension( 'letter', ['A','B','C'] )
.dimension( 'digit', ['1','2','3'], 'letter+digit !== "A1"' )
.dimension( 'symbol' ['!','@','#'] )
.generate( callback );
// outputs 24 combinations, omitting all those where letter is A and digit is 1
Pass in a ProgressiveEvaluation context to make variables available to the validation filter
let context = ProgressiveEvaluation.from({
skip: new Variable('skip').value('bar')
});
new CombinatorialEval()
.dimension( 'word', ['foo','bar','baz','blip'], 'word !== skip' )
.generate( callback, context );
// generates three outputs, skipping the one where word is 'bar'