describefn v1.0.1

describeFn

A super simple testing utility, mostly useful for pure functions.

Example

The function we want to test

/*
  concatenates 2 strings with an optional character in between.
  concat({stringA: 'A', stringB: 'B'}) => AB
  concat({stringA: 'A', stringB: 'B', concatChar: '-'}) => A-B
  
  Maybe not super useful but pure and testable.
*/
var concat = function (params) {
    if (params.stringA === undefined || params.stringB === undefined) {
        throw new Error('Invalid params');
    }
    if (params.concatChar === undefined) {
        params.concatChar = '';
    }
    return params.stringA + params.concatChar + params.stringB;
};

The tests

describeFn({
    fn: concat,
    fnName: 'concat',
    tests: {
        'returns one string containing both passed strings': {
            params: {
                stringA: 'A',
                stringB: 'B'
            },
            result: {equals: 'AB'}
        },
        'inserts the concatChar in the middle of both strings': {
            params: {
                stringA: 'A',
                stringB: 'B',
                concatChar: '-'
            },
            result: {equals: 'A-B'}
        },
        'throws an error if we dont pass enough strings': {
            params: {stringA: 'A'},
            result: {isError: true}
        }
    }
});

Test results

/*
  The function concat,
   returns one string containing both passed strings. √,
   inserts the concatChar in the middle of both strings. √,
   throws an error if we dont pass enough strings. √
*/

For more examples, see examples/describeFnExample.js and tests/tests.js (which runs tests on describeFn itself using describeFn).