mathjs/test/function/expression/eval.test.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

// test eval
var assert = require('assert');
var approx = require('../../../tools/approx');
var error = require('../../../lib/error/index');
var math = require('../../../index');
var Complex = math.type.Complex;
var Matrix = math.type.Matrix;
var Unit = math.type.Unit;
var ResultSet = math.type.ResultSet;

describe('eval', function() {

  it('should evaluate expressions', function() {
    approx.equal(math.eval('(2+3)/4'), 1.25);
    assert.deepEqual(math.eval('sqrt(-4)'), new Complex(0, 2));
  });

  it('should eval a list of expressions', function() {
    assert.deepEqual(math.eval(['1+2', '3+4', '5+6']), [3, 7, 11]);
    assert.deepEqual(math.eval(['a=3', 'b=4', 'a*b']), [3, 4, 12]);
    assert.deepEqual(math.eval(math.matrix(['a=3', 'b=4', 'a*b'])), math.matrix([3, 4, 12]));
    assert.deepEqual(math.eval(['a=3', 'b=4', 'a*b']), [3, 4, 12]);
  });

  it('should eval a series of expressions', function() {
    assert.deepEqual(math.eval('a=3\nb=4\na*b'), new ResultSet([3, 4, 12]));
    assert.deepEqual(math.eval('f(x) = a * x; a=2; f(4)'), new ResultSet([8]));
    assert.deepEqual(math.eval('b = 43; b * 4'), new ResultSet([172]));
  });

  it('should throw an error if wrong number of arguments', function() {
    assert.throws(function () {math.eval()},  error.ArgumentsError);
    assert.throws(function () {math.eval(1,2,3)}, error.ArgumentsError);
  });

  it('should throw an error with a number', function() {
    assert.throws(function () {math.eval(23)}, TypeError);
  });

  it('should throw an error with a unit', function() {
    assert.throws(function () {math.eval(new Unit(5, 'cm'))}, TypeError);
  });

  it('should throw an error with a complex number', function() {
    assert.throws(function () {math.eval(new Complex(2,3))}, TypeError);
  });

  it('should throw an error with a boolean', function() {
    assert.throws(function () {math.eval(true)}, TypeError);
  });

  it('should handle the given scope', function() {
    var scope = {
      a: 3,
      b: 4
    };
    assert.deepEqual(math.eval('a*b', scope), 12);
    assert.deepEqual(math.eval('c=5', scope), 5);
    assert.deepEqual(math.format(math.eval('f(x) = x^a', scope)), 'f(x)');

    assert.deepEqual(Object.keys(scope).length, 4);
    assert.deepEqual(scope.a, 3);
    assert.deepEqual(scope.b, 4);
    assert.deepEqual(scope.c, 5);
    assert.deepEqual(typeof scope.f, 'function');

    assert.equal(scope.f(3), 27);
    scope.a = 2;
    assert.equal(scope.f(3), 9);
    scope.hello = function (name) {
      return 'hello, ' + name + '!';
    };
    assert.deepEqual(math.eval('hello("jos")', scope), 'hello, jos!');
  });

});