mathjs/test/expression/node/Node.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 Node
var assert = require('assert');
var approx = require('../../../tools/approx');
var math = require('../../../index');
var Node = require('../../../lib/expression/node/Node');

describe('Node', function() {
  function MyNode () {}
  MyNode.prototype = new Node();
  MyNode.prototype.forEach = function () {};
  MyNode.prototype.map = function () {
    return new MyNode();
  };

  it ('should create a Node', function () {
    var n = new Node();
    assert(n instanceof Node);
  });

  it ('should throw an error when calling without new operator', function () {
    assert.throws(function () {Node()}, SyntaxError);
  });

  it ('should filter a Node', function () {
    var n = new MyNode();

    assert.deepEqual(n.filter(function () {return true}), [n]);
    assert.deepEqual(n.filter(function (node) {return node instanceof Node}), [n]);
    assert.deepEqual(n.filter(function (node) {return node instanceof Date}), []);
  });

  it ('should transform a Node', function () {
    var a = new MyNode();
    var b = new MyNode();
    var c = a.transform(function (node) {
      return b;
    });
    assert.strictEqual(c, b);

    // no match
    a = new MyNode();
    b = new MyNode();
    c = a.transform(function (node) {
      return node;
    });
    assert.notStrictEqual(c, a);
  });

  it ('should transform a Node using a replacement function', function () {
    var a = new MyNode();
    var b = new MyNode();
    var c = a.transform(function (node) {
      assert.deepEqual(node, a);
      return b;
    });
    assert.strictEqual(c, b);
  });

  it ('should throw an error when cloning a Node interface', function () {
    assert.throws(function () {
      var a = new Node();
      a.clone();
    }, /Cannot clone a Node interface/);
  });

  it ('should test whether an object is a Node', function () {
    assert.equal(Node.isNode(new Node()), true);
    assert.equal(Node.isNode(new Date()), false);
    assert.equal(Node.isNode(2), false);
  });

  it ('should stringify a Node', function () {
    var node = new Node();
    assert.equal(node.toString(), '');
  });

  it ('should throw an error when calling _toTex', function () {
    assert.throws(function () {
      var node = new Node();
      node.type = 'SpecialNode';  //this is necessary because toTex
                                  //returns '' for a Node
      node._toTex();
    }, /_toTex not implemented for this Node/);
  });

  it ('should ignore custom toTex if it returns nothing', function () {
    var callback1 = function (node, callback) {};
    var callback2 = {
      bla: function (node, callbacks) {}
    };
    var mymath = math.create();
    mymath.expression.node.Node.prototype._toTex = function () {
      return 'default';
    };
    var n1 = new mymath.expression.node.Node();
    var n2 = new mymath.expression.node.FunctionNode('bla', []);
    
    assert.equal(n1.toTex(callback1), 'default');
    assert.equal(n2.toTex(callback2), 'bla\\left({}\\right)');
  });

  it ('should throw an error in case of wrong arguments for compile', function () {
    var node = new Node();
    assert.throws(function () {
      node.compile()
    }, /Object expected/);
  });

  it ('should throw an error when compiling an abstract node', function () {
    var node = new Node();
    assert.throws(function () {
      node.compile(math)
    }, /Cannot compile a Node interface/);
  });

  it ('should have an identifier', function () {
    var node = new Node();

    assert.equal(node.getIdentifier(), 'Node');
  });

});