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Change by delta (New Assertion) #621

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merged 4 commits into from
Feb 23, 2016
Merged

Change by delta (New Assertion) #621

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877acb5
Rename change related assertions obj argument to target
lucasfcosta Feb 12, 2016
25359eb
Improve property checks for change related assertions
lucasfcosta Feb 13, 2016
8e8a728
by assertion (a.k.a. assertDelta) implementation
lucasfcosta Feb 22, 2016
10a0bbc
by assertion tests
lucasfcosta Feb 22, 2016
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108 changes: 83 additions & 25 deletions lib/chai/core/assertions.js
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ module.exports = function (chai, _) {
[ 'to', 'be', 'been'
, 'is', 'and', 'has', 'have'
, 'with', 'that', 'which', 'at'
, 'of', 'same' ].forEach(function (chain) {
, 'of', 'same', 'but' ].forEach(function (chain) {
Assertion.addProperty(chain, function () {
return this;
});
Expand Down Expand Up @@ -1634,31 +1634,38 @@ module.exports = function (chai, _) {
* @name change
* @alias changes
* @alias Change
* @param {String} object
* @param {String} target
* @param {String} property name _optional_
* @param {String} message _optional_
* @namespace BDD
* @api public
*/

function assertChanges (object, prop, msg) {
function assertChanges (target, prop, msg) {
if (msg) flag(this, 'message', msg);
var fn = flag(this, 'object');
new Assertion(fn).is.a('function');

var initial;
if (!prop) {
new Assertion(object).is.a('function');
initial = object();
new Assertion(target).is.a('function');
initial = target();
} else {
new Assertion(object, msg).to.have.property(prop);
initial = object[prop];
new Assertion(target, msg).to.have.property(prop);
initial = target[prop];
}

fn();

var final = prop === undefined ? object() : object[prop];
var msgObj = prop === undefined ? initial : '.' + prop;
var final = prop === undefined || prop === null ? target() : target[prop];
var msgObj = prop === undefined || prop === null ? initial : '.' + prop;

// This gets flagged because of the .by(delta) assertion
flag(this, 'deltaMsgObj', msgObj);
flag(this, 'initialDeltaValue', initial);
flag(this, 'finalDeltaValue', final);
flag(this, 'deltaBehavior', 'change');
flag(this, 'realDelta', final !== initial);

this.assert(
initial !== final
Expand All @@ -1682,31 +1689,37 @@ module.exports = function (chai, _) {
* @name increase
* @alias increases
* @alias Increase
* @param {String} object
* @param {String} target
* @param {String} property name
* @param {String} message _optional_
* @namespace BDD
* @api public
*/

function assertIncreases (object, prop, msg) {
function assertIncreases (target, prop, msg) {
if (msg) flag(this, 'message', msg);
var fn = flag(this, 'object');
new Assertion(fn).is.a('function');

var initial;
if (!prop) {
new Assertion(object).is.a('function');
initial = object();
new Assertion(target).is.a('function');
initial = target();
} else {
new Assertion(object, msg).to.have.property(prop);
initial = object[prop];
new Assertion(target, msg).to.have.property(prop);
initial = target[prop];
}

fn();

var final = prop === undefined ? object() : object[prop];
var msgObj = prop === undefined ? initial : '.' + prop;
var final = prop === undefined || prop === null ? target() : target[prop];
var msgObj = prop === undefined || prop === null ? initial : '.' + prop;

flag(this, 'deltaMsgObj', msgObj);
flag(this, 'initialDeltaValue', initial);
flag(this, 'finalDeltaValue', final);
flag(this, 'deltaBehavior', 'increase');
flag(this, 'realDelta', final - initial);

this.assert(
final - initial > 0
Expand All @@ -1730,31 +1743,37 @@ module.exports = function (chai, _) {
* @name decrease
* @alias decreases
* @alias Decrease
* @param {String} object
* @param {String} target
* @param {String} property name
* @param {String} message _optional_
* @namespace BDD
* @api public
*/

function assertDecreases (object, prop, msg) {
function assertDecreases (target, prop, msg) {
if (msg) flag(this, 'message', msg);
var fn = flag(this, 'object');
new Assertion(fn).is.a('function');

var initial;
if (!prop) {
new Assertion(object).is.a('function');
initial = object();
new Assertion(target).is.a('function');
initial = target();
} else {
new Assertion(object, msg).to.have.property(prop);
initial = object[prop];
new Assertion(target, msg).to.have.property(prop);
initial = target[prop];
}

fn();

var final = prop === undefined ? object() : object[prop];
var msgObj = prop === undefined ? initial : '.' + prop;
var final = prop === undefined || prop === null ? target() : target[prop];
var msgObj = prop === undefined || prop === null ? initial : '.' + prop;

flag(this, 'deltaMsgObj', msgObj);
flag(this, 'initialDeltaValue', initial);
flag(this, 'finalDeltaValue', final);
flag(this, 'deltaBehavior', 'decrease');
flag(this, 'realDelta', initial - final);

this.assert(
final - initial < 0
Expand All @@ -1766,6 +1785,45 @@ module.exports = function (chai, _) {
Assertion.addChainableMethod('decrease', assertDecreases);
Assertion.addChainableMethod('decreases', assertDecreases);

/**
* ### .by
*
* Defines an amount for increase/decrease assertions.
*
* var obj = { val: 10 };
* var dec = function() { obj.val -= 5 };
* var inc = function() {obj.val += 10};
* expect(dec).to.decrease(obj, 'val').by(5);
* expect(inc).to.increase(obj, 'val').by(10);
*
* @name by
* @namespace BDD
* @api public
*/

function assertDelta(delta) {
var msgObj = flag(this, 'deltaMsgObj');
var initial = flag(this, 'initialDeltaValue');
var final = flag(this, 'finalDeltaValue');
var behavior = flag(this, 'deltaBehavior');
var realDelta = flag(this, 'realDelta');

var expression;
if (behavior === 'change') {
expression = Math.abs(final - initial) === Math.abs(delta);
} else {
expression = realDelta === Math.abs(delta);
}

this.assert(
expression
, 'expected ' + msgObj + ' to ' + behavior + ' by ' + delta
, 'expected ' + msgObj + ' to not ' + behavior + ' by ' + delta
);
}

Assertion.addMethod('by', assertDelta);

/**
* ### .extensible
*
Expand Down