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var expect = require("expect.js"),
__with__ = require("../lib/__with__.js"),
__set__ = require("../lib/__set__.js"),
vm = require("vm"),
expectReferenceError = expectError(ReferenceError),
expectTypeError = expectError(TypeError);
function expectError(ErrConstructor) {
return function expectReferenceError(err) {
expect(err.constructor.name).to.be(ErrConstructor.name);
};
}
describe("__with__", function() {
var moduleFake;
beforeEach(function () {
moduleFake = {
module: {
exports: {}
},
myValue: 0, // copy by value
myReference: {} // copy by reference
};
//__with__ requires __set__ to be in scope
vm.runInNewContext(
"module.exports.__set__ = " + __set__.toString() + "; " +
"__with__ = " + __with__.toString() + "; " +
"getValue = function () { return myValue; }; " +
"getReference = function () { return myReference; }; ",
moduleFake
);
});
it("should return a function that can be invoked with a callback which guarantees __sets__ undo function is called for you at the end", function () {
var newObj = { hello: "hello" };
expect(moduleFake.getValue()).to.be(0);
expect(moduleFake.getReference()).to.eql({});
moduleFake.__with__({
myValue: 2,
myReference: newObj
})(function() {
//changes will be visible from within this callback function
expect(moduleFake.getValue()).to.be(2);
expect(moduleFake.getReference()).to.be(newObj);
});
//undo will automatically get called for you after returning from your callback function
expect(moduleFake.getValue()).to.be(0);
expect(moduleFake.getReference()).to.eql({});
});
it("should still revert values if the callback throws an exception", function(){
var newObj = { hello: "hello" };
function withError(){
moduleFake.__with__({
myValue: 2,
myReference: newObj
})(function() {
throw new Error("something went wrong...");
});
}
expect(withError).to.throwError();
expect(moduleFake.getValue()).to.be(0);
expect(moduleFake.getReference()).to.eql({});
});
it("should throw an error if something other than a function is passed as the callback", function() {
var newObj = { hello: "hello" },
withFunction = moduleFake.__with__({
myValue: 2,
myReference: newObj
});
callWithFunction = function(){
var args = arguments;
return function() {
withFunction.apply(null, args);
};
};
expect(callWithFunction(1)).to.throwError();
expect(callWithFunction("a string")).to.throwError();
expect(callWithFunction({})).to.throwError();
expect(callWithFunction(function(){})).to.not.throwError();
});
});
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