"use strict";
var assert = require("assert"),
	IfNullExpression = require("../../../../lib/pipeline/expressions/IfNullExpression"),
	Expression = require("../../../../lib/pipeline/expressions/Expression");


module.exports = {

	"IfNullExpression": {

		"constructor()": {

			"should not throw Error when constructing without args": function testConstructor(){
				assert.doesNotThrow(function(){
					new IfNullExpression();
				});
			}

		},

		"#getOpName()": {

			"should return the correct op name; $ifNull": function testOpName(){
				assert.equal(new IfNullExpression().getOpName(), "$ifNull");
			}

		},

		"#getFactory()": {

			"should return the constructor for this class": function factoryIsConstructor(){
				assert.strictEqual(new IfNullExpression().getFactory(), undefined);
			}

		},

		"#evaluate()": {

			"should return the left hand side if the left hand side is not null or undefined": function testStuff(){
				assert.strictEqual(Expression.parseOperand({$ifNull:["$a", "$b"]}).evaluate({a:1, b:2}), 1);
			},
			"should return the right hand side if the left hand side is null or undefined": function testStuff(){
				assert.strictEqual(Expression.parseOperand({$ifNull:["$a", "$b"]}).evaluate({a:null, b:2}), 2);
				assert.strictEqual(Expression.parseOperand({$ifNull:["$a", "$b"]}).evaluate({b:2}), 2);
			}
		}

	}

};

if (!module.parent)(new(require("mocha"))()).ui("exports").reporter("spec").addFile(__filename).run(process.exit);