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wrap-method.js
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wrap-method.js
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"use strict";
var getPropertyDescriptor = require("./get-property-descriptor");
var valueToString = require("./value-to-string");
var hasOwn = Object.prototype.hasOwnProperty;
function isFunction(obj) {
return typeof obj === "function" || !!(obj && obj.constructor && obj.call && obj.apply);
}
function mirrorProperties(target, source) {
for (var prop in source) {
if (!hasOwn.call(target, prop)) {
target[prop] = source[prop];
}
}
}
// Cheap way to detect if we have ES5 support.
var hasES5Support = "keys" in Object;
module.exports = function wrapMethod(object, property, method) {
if (!object) {
throw new TypeError("Should wrap property of object");
}
if (typeof method !== "function" && typeof method !== "object") {
throw new TypeError("Method wrapper should be a function or a property descriptor");
}
function checkWrappedMethod(wrappedMethod) {
var error;
if (!isFunction(wrappedMethod)) {
error = new TypeError("Attempted to wrap " + (typeof wrappedMethod) + " property " +
valueToString(property) + " as function");
} else if (wrappedMethod.restore && wrappedMethod.restore.sinon) {
error = new TypeError("Attempted to wrap " + valueToString(property) + " which is already wrapped");
} else if (wrappedMethod.calledBefore) {
var verb = wrappedMethod.returns ? "stubbed" : "spied on";
error = new TypeError("Attempted to wrap " + valueToString(property) + " which is already " + verb);
}
if (error) {
if (wrappedMethod && wrappedMethod.stackTrace) {
error.stack += "\n--------------\n" + wrappedMethod.stackTrace;
}
throw error;
}
}
var error, wrappedMethod, i;
function simplePropertyAssignment() {
wrappedMethod = object[property];
checkWrappedMethod(wrappedMethod);
object[property] = method;
method.displayName = property;
}
// Firefox has a problem when using hasOwn.call on objects from other frames.
var owned = object.hasOwnProperty ? object.hasOwnProperty(property) : hasOwn.call(object, property);
if (hasES5Support) {
var methodDesc = (typeof method === "function") ? {value: method} : method;
var wrappedMethodDesc = getPropertyDescriptor(object, property);
if (!wrappedMethodDesc) {
error = new TypeError("Attempted to wrap " + (typeof wrappedMethod) + " property " +
property + " as function");
} else if (wrappedMethodDesc.restore && wrappedMethodDesc.restore.sinon) {
error = new TypeError("Attempted to wrap " + property + " which is already wrapped");
}
if (error) {
if (wrappedMethodDesc && wrappedMethodDesc.stackTrace) {
error.stack += "\n--------------\n" + wrappedMethodDesc.stackTrace;
}
throw error;
}
var types = Object.keys(methodDesc);
for (i = 0; i < types.length; i++) {
wrappedMethod = wrappedMethodDesc[types[i]];
checkWrappedMethod(wrappedMethod);
}
mirrorProperties(methodDesc, wrappedMethodDesc);
for (i = 0; i < types.length; i++) {
mirrorProperties(methodDesc[types[i]], wrappedMethodDesc[types[i]]);
}
Object.defineProperty(object, property, methodDesc);
// catch failing assignment
// this is the converse of the check in `.restore` below
if ( typeof method === "function" && object[property] !== method ) {
// correct any wrongdoings caused by the defineProperty call above,
// such as adding new items (if object was a Storage object)
delete object[property];
simplePropertyAssignment();
}
} else {
simplePropertyAssignment();
}
method.displayName = property;
// Set up a stack trace which can be used later to find what line of
// code the original method was created on.
method.stackTrace = (new Error("Stack Trace for original")).stack;
method.restore = function () {
// For prototype properties try to reset by delete first.
// If this fails (ex: localStorage on mobile safari) then force a reset
// via direct assignment.
if (!owned) {
// In some cases `delete` may throw an error
try {
delete object[property];
} catch (e) {} // eslint-disable-line no-empty
// For native code functions `delete` fails without throwing an error
// on Chrome < 43, PhantomJS, etc.
} else if (hasES5Support) {
Object.defineProperty(object, property, wrappedMethodDesc);
}
if (hasES5Support) {
var descriptor = getPropertyDescriptor(object, property);
if (descriptor && descriptor.value === method) {
object[property] = wrappedMethod;
}
}
else {
// Use strict equality comparison to check failures then force a reset
// via direct assignment.
if (object[property] === method) {
object[property] = wrappedMethod;
}
}
};
method.wrappedMethod = wrappedMethod;
method.restore.sinon = true;
if (!hasES5Support) {
mirrorProperties(method, wrappedMethod);
}
return method;
};