mocha example

gistfile1.js

describe('fxpay', function() {
  describe('purchase()', function() {
    it('should error if mozPay() is undefined', function(done) {
      var productId = '123';

      fxpay.purchase(productId, {
        onpurchase: function(error) {
          assert.equal(error, 'PAY_PLATFORM_UNAVAILABLE');
          done();
        },
        mozPay: undefined  // override navigator.mozPay
      });

    });
  });
});