chai-bignumber
Chai assertions for comparing arbitrary-precision decimals using the bignumber.js library.
Installation
npm install --save-dev chai-bignumber
Usage
var chai = require('chai');
//use default BigNumber
chai.use(require('chai-bignumber')());
//use custom BigNumber
chai.use(require('chai-bignumber')(BigNumber));
Assertions
The following assertion methods are provided and will override the existing
builtin assertions if the bignumber property is explicitly set as part of
the assertion chain:
- equal/equals/eq
- above/gt/greaterThan
- least/gte/greaterThanOrEqual
- below/lt/lessThan
- most/lte/lessThanOrEqual
The above methods have the following signature: (value, dp, rm).
Where dp is an optional argument which specifies the number of decimal places
to round each side of the comparison to (values are not rounded by default),
while rm is an optional argument which specifies the
rounding mode
as supported by bignumber.js (defaults to BigNumber.ROUND_HALF_UP).
A set of additional assertion properties is also provided:
- finite
- integer
- negative
- zero
Values can be instances of number, BigNumber or string which can be
converted into a valid number. Only BDD style (expect or should) assertions
are supported.
Examples
Methods:
var result = new BigNumber('100000000000000000').plus(1);
var expected = '100000000000000001';
result.should.be.bignumber.equal(expected);
expect(result).to.be.bignumber.at.most(expected);
'1000'.should.be.bignumber.lessThan(2000);
Methods with rounding:
var BigNumber = require('bignumber.js');
(100.343).should.be.bignumber.equal(100.341, 2);
(100.349).should.be.bignumber.equal(100.341, 2, BigNumber.ROUND_DOWN);
Properties:
(100 / 0).should.not.be.finite;
expect(10).to.be.integer;
(-100).should.be.negative;
expect(1 - 1).to.be.zero;