index.js
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'use strict';
var define = require('../');
var test = require('tape');
var keys = require('object-keys');
var arePropertyDescriptorsSupported = function () {
var obj = { a: 1 };
try {
Object.defineProperty(obj, 'x', { value: obj });
return obj.x === obj;
} catch (e) { /* this is IE 8. */
return false;
}
};
var descriptorsSupported = !!Object.defineProperty && arePropertyDescriptorsSupported();
var hasSymbols = typeof Symbol === 'function' && typeof Symbol('foo') === 'symbol';
test('defineProperties', function (dt) {
dt.test('with descriptor support', { skip: !descriptorsSupported }, function (t) {
var getDescriptor = function (value) {
return {
configurable: true,
enumerable: false,
value: value,
writable: true
};
};
var obj = {
a: 1,
b: 2,
c: 3
};
t.deepEqual(keys(obj), ['a', 'b', 'c'], 'all literal-set keys start enumerable');
define(obj, {
b: 3,
c: 4,
d: 5
});
t.deepEqual(obj, {
a: 1,
b: 2,
c: 3
}, 'existing properties were not overridden');
t.deepEqual(Object.getOwnPropertyDescriptor(obj, 'd'), getDescriptor(5), 'new property "d" was added and is not enumerable');
t.deepEqual(['a', 'b', 'c'], keys(obj), 'new keys are not enumerable');
define(obj, {
a: 2,
b: 3,
c: 4
}, {
a: function () { return true; },
b: function () { return false; }
});
t.deepEqual(obj, {
b: 2,
c: 3
}, 'properties only overriden when predicate exists and returns true');
t.deepEqual(Object.getOwnPropertyDescriptor(obj, 'd'), getDescriptor(5), 'existing property "d" remained and is not enumerable');
t.deepEqual(Object.getOwnPropertyDescriptor(obj, 'a'), getDescriptor(2), 'existing property "a" was overridden and is not enumerable');
t.deepEqual(['b', 'c'], keys(obj), 'overridden keys are not enumerable');
t.end();
});
dt.test('without descriptor support', { skip: descriptorsSupported }, function (t) {
var obj = {
a: 1,
b: 2,
c: 3
};
define(obj, {
b: 3,
c: 4,
d: 5
});
t.deepEqual(obj, {
a: 1,
b: 2,
c: 3,
d: 5
}, 'existing properties were not overridden, new properties were added');
define(obj, {
a: 2,
b: 3,
c: 4
}, {
a: function () { return true; },
b: function () { return false; }
});
t.deepEqual(obj, {
a: 2,
b: 2,
c: 3,
d: 5
}, 'properties only overriden when predicate exists and returns true');
t.end();
});
dt.end();
});
test('symbols', { skip: !hasSymbols }, function (t) {
var sym = Symbol('foo');
var obj = {};
var aValue = {};
var bValue = {};
var properties = { a: aValue };
properties[sym] = bValue;
define(obj, properties);
t.deepEqual(Object.keys(obj), [], 'object has no enumerable keys');
t.deepEqual(Object.getOwnPropertyNames(obj), ['a'], 'object has non-enumerable "a" key');
t.deepEqual(Object.getOwnPropertySymbols(obj), [sym], 'object has non-enumerable symbol key');
t.equal(obj.a, aValue, 'string keyed value is defined');
t.equal(obj[sym], bValue, 'symbol keyed value is defined');
t.end();
});