mathjs/test/expression/node/ConditionalNode.test.js

// test ConditionalNode
var assert = require('assert'),
    approx = require('../../../tools/approx'),
    math = require('../../../index'),
    Node = require('../../../lib/expression/node/Node'),
    ConstantNode = require('../../../lib/expression/node/ConstantNode'),
    SymbolNode = require('../../../lib/expression/node/SymbolNode'),
    AssignmentNode = require('../../../lib/expression/node/AssignmentNode'),
    ConditionalNode = require('../../../lib/expression/node/ConditionalNode');

describe('ConditionalNode', function() {
  var condition = new ConstantNode(true);
  var zero = new ConstantNode(0);
  var one = new ConstantNode(1);
  var two = new ConstantNode(2);
  var three = new ConstantNode(3);
  var a = new AssignmentNode('a', two);
  var b = new AssignmentNode('b', three);

  it ('should create a ConditionalNode', function () {
    var n = new ConditionalNode(condition, a, b);
    assert(n instanceof ConditionalNode);
    assert(n instanceof Node);
    assert.equal(n.type, 'ConditionalNode');
  });

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

  it ('should throw an error when creating without arguments', function () {
    assert.throws(function () {new ConditionalNode()}, TypeError);
    assert.throws(function () {new ConditionalNode(condition)}, TypeError);
    assert.throws(function () {new ConditionalNode(condition, a)}, TypeError);
    assert.throws(function () {new ConditionalNode(condition, null, b)}, TypeError);
  });

  it ('should lazy evaluate a ConditionalNode', function () {
    var n = new ConditionalNode(condition, a, b);
    var expr = n.compile(math);
    var scope = {};
    assert.equal(expr.eval(scope), 2);
    assert.deepEqual(scope, {a: 2});
  });

  describe('evaluate', function () {
    var condition = new ConditionalNode(new SymbolNode('a'), one, zero);

    it('should evaluate boolean conditions', function() {
      assert.equal(condition.compile(math).eval({a: true}), 1);
      assert.equal(condition.compile(math).eval({a: false}), 0);
    });

    it('should evaluate number conditions', function() {
      assert.equal(condition.compile(math).eval({a: 1}), 1);
      assert.equal(condition.compile(math).eval({a: 4}), 1);
      assert.equal(condition.compile(math).eval({a: -1}), 1);
      assert.equal(condition.compile(math).eval({a: 0}), 0);
    });

    it('should evaluate bignumber conditions', function() {
      assert.equal(condition.compile(math).eval({a: math.bignumber(1)}), 1);
      assert.equal(condition.compile(math).eval({a: math.bignumber(4)}), 1);
      assert.equal(condition.compile(math).eval({a: math.bignumber(-1)}), 1);
      assert.equal(condition.compile(math).eval({a: math.bignumber(0)}), 0);
    });

    it('should evaluate complex number conditions', function() {
      assert.equal(condition.compile(math).eval({a: math.complex(2, 3)}), 1);
      assert.equal(condition.compile(math).eval({a: math.complex(2, 0)}), 1);
      assert.equal(condition.compile(math).eval({a: math.complex(0, 3)}), 1);
      assert.equal(condition.compile(math).eval({a: math.complex(0, 0)}), 0);
    });

    it('should evaluate string conditions', function() {
      assert.equal(condition.compile(math).eval({a: 'hello'}), 1);
      assert.equal(condition.compile(math).eval({a: ''}), 0);
    });

    it('should evaluate unit conditions', function() {
      assert.equal(condition.compile(math).eval({a: math.unit('5cm')}), 1);
      assert.equal(condition.compile(math).eval({a: math.unit('0 inch')}), 0);
      assert.equal(condition.compile(math).eval({a: math.unit('meter')}), 0);
    });

    it('should evaluate null conditions', function() {
      assert.equal(condition.compile(math).eval({a: null}), 0);
    });

    it('should evaluate undefined conditions', function() {
      assert.equal(condition.compile(math).eval({a: undefined}), 0);
    });

    it('should throw an error in case of unsupported type of conditions', function() {
      assert.throws(function () {condition.compile(math).eval({a: {}})});
      assert.throws(function () {condition.compile(math).eval({a: []})});
      assert.throws(function () {condition.compile(math).eval({a: math.matrix()})});
    });
  });

  it ('should filter a ConditionalNode', function () {
    var n = new ConditionalNode(condition, a, b);

    assert.deepEqual(n.filter(function (node) {return node instanceof ConditionalNode}),  [n]);
    assert.deepEqual(n.filter(function (node) {return node instanceof ConstantNode}),  [condition, two, three]);
    assert.deepEqual(n.filter(function (node) {return node instanceof ConstantNode && node.value == '2'}),  [two]);
  });

  it ('should transform a ConditionalNodes condition', function () {
    var condition = new ConstantNode(1);
    var a = new ConstantNode(2);
    var b = new ConstantNode(3);
    var n = new ConditionalNode(condition, a, b);

    var e = new ConstantNode(4);
    var f = n.transform(function (node) {
      return node instanceof ConstantNode && node.value == '1' ? e : node;
    });

    assert.notStrictEqual(f, n);
    assert.deepEqual(f.condition,  e);
    assert.deepEqual(f.trueExpr,  a);
    assert.deepEqual(f.falseExpr,  b);
  });

  it ('should transform a ConditionalNodes trueExpr', function () {
    var condition = new ConstantNode(1);
    var a = new ConstantNode(2);
    var b = new ConstantNode(3);
    var n = new ConditionalNode(condition, a, b);

    var e = new ConstantNode(4);
    var f = n.transform(function (node) {
      return node instanceof ConstantNode && node.value == '2' ? e : node;
    });

    assert.notStrictEqual(f, n);
    assert.deepEqual(f.condition,  condition);
    assert.deepEqual(f.trueExpr,  e);
    assert.deepEqual(f.falseExpr,  b);
  });

  it ('should transform a ConditionalNodes falseExpr', function () {
    var condition = new ConstantNode(1);
    var a = new ConstantNode(2);
    var b = new ConstantNode(3);
    var n = new ConditionalNode(condition, a, b);

    var e = new ConstantNode(4);
    var f = n.transform(function (node) {
      return node instanceof ConstantNode && node.value == '3' ? e : node;
    });

    assert.notStrictEqual(f, n);
    assert.deepEqual(f.condition, condition);
    assert.deepEqual(f.trueExpr, a);
    assert.deepEqual(f.falseExpr, e);
  });

  it ('should transform a ConditionalNode itself', function () {
    var condition = new ConstantNode(1);
    var a = new ConstantNode(2);
    var b = new ConstantNode(3);
    var n = new ConditionalNode(condition, a, b);

    var e = new ConstantNode(5);
    var f = n.transform(function (node) {
      return node instanceof ConditionalNode ? e : node;
    });

    assert.strictEqual(f, e);
  });

  it ('should stringify a ConditionalNode', function () {
    var n = new ConditionalNode(condition, a, b);

    assert.equal(n.toString(), '(true) ? (a = 2) : (b = 3)');
  });

  it ('should LaTeX a ConditionalNode', function () {
    var n = new ConditionalNode(condition, a, b);

    assert.equal(n.toTex(), '\\left\\{\\begin{array}{l l}{{a}={2}}, &\\quad{\\text{if}\\;true}\\\\{{b}={3}}, &\\quad{\\text{otherwise}}\\end{array}\\right.');
  });

});