dvbcss-clocks/tests/specs/Correlation.test.js

Javascript library implementing clock objects for modelling timelines. Useful in DVB CSS implementations.

/****************************************************************************
 * Copyright 2017 British Broadcasting Corporation
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*****************************************************************************/

var Correlation = require("Correlation");

describe("Correlation", function() {
	it("exists", function() {
		expect(Correlation).toBeDefined();
	});
    
	it("takes two arguments that set the parentTime and childTime properties, and the initialError and errorGrowthRate default to zero.", function() {
		var c = new Correlation(50,76);
		expect(c.parentTime).toBe(50);
		expect(c.childTime).toBe(76);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);
	});
	
	it("takes four arguments that set the parentTime, childTime, initialError and errorGrowthRate properties.", function() {
		var c = new Correlation(50,76,7,1.2);
		expect(c.parentTime).toBe(50);
		expect(c.childTime).toBe(76);
		expect(c.initialError).toBe(7);
		expect(c.errorGrowthRate).toBe(1.2);
	});
	
	it("can take a single argument being an object with properties parentTime, childTime, initialError and errorGrowthRate, or a subset thereof", function() {
		var c;

		c = new Correlation({});
		expect(c.parentTime).toBe(0);
		expect(c.childTime).toBe(0);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation({parentTime:5});
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(0);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation({parentTime:5, childTime:10});
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation({parentTime:5, childTime:10, initialError:7});
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(7);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation({parentTime:5, childTime:10, initialError:7, errorGrowthRate:99});
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(7);
		expect(c.errorGrowthRate).toBe(99);
	});
	
	it("can take a single argument being an array with between 0 and 4 values corresponding to parentTime, childTime, initialError and errorGrowthRate in that order", function() {
		var c;
		
		c = new Correlation([]);
		expect(c.parentTime).toBe(0);
		expect(c.childTime).toBe(0);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation([5]);
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(0);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation([5,10]);
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(0);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation([5,10,7]);
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(7);
		expect(c.errorGrowthRate).toBe(0);

		c = new Correlation([5,10,7,99]);
		expect(c.parentTime).toBe(5);
		expect(c.childTime).toBe(10);
		expect(c.initialError).toBe(7);
		expect(c.errorGrowthRate).toBe(99);
		
	});
	
	it("is immutable. parentTime, childTime, initialError and errorGrowthRate properties can be read but not set", function() {
		var c = new Correlation(1,2,3,4);
		
		expect(function() { c.parentTime=10;}).toThrow();
		expect(function() { c.childTime=10;}).toThrow();
		expect(function() { c.initialError=10;}).toThrow();
		expect(function() { c.errorGrowthRate=10;}).toThrow();
	});
	
	it("can be compared for by-value equality using the equals() method", function() {
		expect(new Correlation(1,2,3,4).equals(new Correlation(1,2,3,4))).toBeTruthy();
		expect(new Correlation(1,2,0,0).equals(new Correlation(1,2))).toBeTruthy();
		expect(new Correlation(1,2).equals(new Correlation(1,2,0,0))).toBeTruthy();
		expect(new Correlation(1,2).equals(new Correlation(1,2,0,0))).toBeTruthy();

		expect(new Correlation(1,2,3,4).equals(new Correlation(1,2))).toBeFalsy();
		expect(new Correlation(1,2).equals(new Correlation(1,2,3,4))).toBeFalsy();
	});
	
	it("can build new variants of itself with altered values for parentTime, childTime, initialError and errorGrowthRate via the butWith() method by passing an object with them set as properties", function() {
		var c = new Correlation(1,2,3,4);
		
		var c2 = c.butWith();
		expect(c).toEqual(c2);
		
		var c3 = c.butWith({parentTime:7});
		expect(c3).toEqual(new Correlation(7,2,3,4));
		
		var c4 = c.butWith({childTime:99});
		expect(c4).toEqual(new Correlation(1,99,3,4));

		var c5 = c.butWith({initialError:888});
		expect(c5).toEqual(new Correlation(1,2,888,4));

		var c6 = c.butWith({errorGrowthRate:1000});
		expect(c6).toEqual(new Correlation(1,2,3,1000));
	});
	
	
});