Install Jest using
yarn
:Bitcoin is also down by 1.9%, having fallen from $10,678 to around $10,400, at press time. The Australia ASX All Ordinaries fell 1.35%, while the S&P 500 futures fell about 2% on the news. Babel: Choice is a 2D action-adventure Roguelike game which combines with the elements of RPG and shooting games. In the game, the player will play the part of Alexander, the son of the evil duke, aiming to break through the perilous and capricious Tower of Evil.
Or
npm
:Note: Jest documentation uses
yarn
commands, but npm
will also work. You can compare yarn
and npm
commands in the yarn docs, here.Let's get started by writing a test for a hypothetical function that adds two numbers. First, create a
sum.js
file:Then, create a file named
sum.test.js
. This will contain our actual test:Add the following section to your
package.json
:Finally, run
yarn test
or npm run test
and Jest will print this message:You just successfully wrote your first test using Jest!
This test used
expect
and toBe
to test that two values were exactly identical. To learn about the other things that Jest can test, see Using Matchers.Running from command line
You can run Jest directly from the CLI (if it's globally available in your
PATH
, e.g. by yarn global add jest
or npm install jest --global
) with a variety of useful options.Here's how to run Jest on files matching
my-test
, using config.json
as a configuration file and display a native OS notification after the run:If you'd like to learn more about running
jest
through the command line, take a look at the Jest CLI Options page.Additional Configuration
Generate a basic configuration file
Based on your project, Jest will ask you a few questions and will create a basic configuration file with a short description for each option: Podgrasp 2 1 0 – podcast player.
Using Babel
![Babel: Choice 1 0 Babel: Choice 1 0](https://steamcdn-a.akamaihd.net/steam/apps/430170/ss_706f50a10c63d690cff32da550d441cd035bfa0c.1920x1080.jpg)
To use Babel, install required dependencies via
yarn
:Configure Babel to target your current version of Node by creating a
babel.config.js
file in the root of your project:The ideal configuration for Babel will depend on your project. See Babel's docs for more details.
Jest will set
process.env.NODE_ENV
to 'test'
if it's not set to something else. You can use that in your configuration to conditionally setup only the compilation needed for Jest, e.g.Note:
babel-jest
is automatically installed when installing Jest and will automatically transform files if a babel configuration exists in your project. To avoid this behavior, you can explicitly reset the transform
configuration option:Jest 24 dropped support for Babel 6. We highly recommend you to upgrade to Babel 7, which is actively maintained. However, if you cannot upgrade to Babel 7, either keep using Jest 23 or upgrade to Jest 24 with
babel-jest
locked at version 23, like in the example below:While we generally recommend using the same version of every Jest package, this workaround will allow you to continue using the latest version of Jest with Babel 6 for now.
Using webpack
Jest can be used in projects that use webpack to manage assets, styles, and compilation. webpack does offer some unique challenges over other tools. Refer to the webpack guide to get started.
Using parcel
Jest can be used in projects that use parcel-bundler to manage assets, styles, and compilation similar to webpack. Parcel requires zero configuration. Refer to the official docs to get started.
Using TypeScript
Jest supports TypeScript, via Babel. First, make sure you followed the instructions on using Babel above. Next, install the
@babel/preset-typescript
via yarn
:Then add
@babel/preset-typescript
to the list of presets in your babel.config.js
.However, there are some caveats to using TypeScript with Babel. Because TypeScript support in Babel is transpilation, Jest will not type-check your tests as they are run. If you want that, you can use ts-jest.
Babel is a loop-avoiding distance-vector routing protocol forIPv6 and IPv4 with fast convergence properties. It is based on theideas in DSDV,AODV andCisco's EIGRP, but isdesigned to work well not only in wired networks but also in wireless meshnetworks, and has been extended with support for overlay networks. Babelis in the process of becoming anIETF Standard.
See download below for source and binaries.
Reading
Specifications
RFCs:
- The Babel extension mechanism : RFC 7557;
- Babel HMAC Cryptographic Authentication : RFC 7298.
Internet Drafts:
- The Babel routing protocol (work in progress, obsoletes RFC 6126);
- Applicability of the Babel routing protocol (work in progress);
- Delay-based Metric Extension for the Babel Routing Protocol (work in progress);
- Diversity Routing for the Babel Routing Protocol (work in progress);
- Source-specific Routing for the Babel Routing Protocol (work in progress);
- TOS-Specific routing for the Babel Routing Protocol (work in progress);
- Babel Cryptographic Authentification (work in progress, obsoletes RFC 7298);
- BabelRouting Protocol over Datagram Transport Layer Security (work inprogress).
Work in progress tends to be made available athttps://github.com/jech/babel-drafts
Human-friendly documents
- the Babel and AHCP FAQ.
- slides from a talk about Babel.
- The
babeld
(8) manual page. - The changelog for babeld.
Our papers
M. Boutier and J Chroboczek.Source-Specific routing.In IFIP Networking 2015. 2015.
B. Jonglez, M. Boutier and J. Chroboczek.Delay-based routing.Unpublished draft. 2015.
Other papers
M. Abolhasan, B. Hagelstein, J. C.-P. Wang.Real-worldperformance of current proactive multi-hop mesh protocols.Asia-Pacific Conference on Communication (APCC 2009), Shanghai,China. 2009.
David Murray, Michael Dixon and TerryKoziniec. AnExperimental Comparison of Routing Protocols in Multi Hop Ad HocNetworks. In Proc. ATNAC 2010. 2010.
Jesús Friginal, David de Andrés, Juan-Carlos Ruiz,Pedro Gil.TowardsBenchmarking Routing Protocols in Wireless Mesh Networks.In Ad Hoc Networks Collections 6 2 2 x 2. , Volume 9, Issue 8, November 2011, Pages1374-1388.
María E. Villapol et al.Performancecomparison of mesh routing protocols in an experimental network withbandwidth restrictions in the border router. Revista de la Facultadde Ingeniería U.C.V., 28:1. 2012.
Jesús Friginal, Juan-Carlos Ruiz, David de Andrés andAntonio Bustos.Mitigatingthe Impact of Ambient Noise on Wireless Mesh Networks Using AdaptiveLink-Quality-based Packet Replication. DSN'2012:1-8. 2013.
Contact and development information
To contact us, please write to theBabelusers mailing list. You may browse the archiveson Alioth,at Gmane using HTTP,at Gmane using NNTP,and at mail-archive.com.
There is also a #babel channel on Freenode, wherea number of competent people tend to lurk.
Babel features
If you do not have brains you follow the sameroute twice. — Greek proverb
Babel's main features are the following:
- robust and efficient on both wireless mesh networks and wired,structured networks;
- flexible choice of metrics, including hop-count, packet loss, radiodiversity and delay-based;
- support for double-stack (IPv4 and IPv6s) networks;
- support for source-specific routing for multihoming;
- small implementation, suitable for embedded systems.
Babel on wired networks
Babel works efficiently on ordinary wired networks. When babeld detectsa wired link, it enables a number of optimisations that make it asefficient as traditional routing protocols. (These optimisations need tobe manually disabled on exotic links, such as point-to-multipoint VPNs.)
Babel on wireless networks
When it detects a wireless link, babeld disables all optimisations anduses a metric based on packet loss that is designed for the 802.11 (WiFi)MAC (the ETX metric). This slows down convergence, but ensuresthat the peculiar characteristics of wireless links do not break routing.
Babel is robust in the presence of mobility: in a pure mesh network,Babel never creates a routing loop, and in a prefix-based network, allrouting loops are guaranteed to disappear as soon as one update wentaround a loop (there is no 'counting to infinity').
Babel enjoys fairly fast convergence. Since Babel uses triggeredupdates and explicit requests for routing information, it usuallyconverges almost immediately after the link quality measure hascompleted. This initial solution is not optimal — after converging toa merely satisfactory set of routes, Babel will take its sweet time beforeoptimising the routing tables. In the presence of heavy packet loss,converging on an optimal set of routes may take up to 40 seconds or so(with the default update interval of 16 seconds).
Babeld can optionally take radio frequency into account in order toavoid interference. This dramatically improves performance onmulti-frequency networks.
Babel on overlay networks
The Babel-RTT protocol extension allows Babel to optimiserouting in overlay networks. This is described in detailin Baptiste Jonglez'report and in a RTT-basedrouting draft article. Search for 'enable-timestamps' inthe manual page.
Babel on double-stack networks
Babel is a hybrid IPv6 and IPv4 protocol: a single updatepacket can carry both IPv6 and IPv4 routes (this is similar to howmulti-protocol BGP works). This makes Babel particularly efficient andsimple to manage on double-stack (IPv6 and IPv4) networks.
Source-specific routing and multihoming
Babel has support for source-specific routing (sometimescalled SADR), which allows a form of multihoming withoutcooperation from the ISP. This is described in detail inSource-Specific routing.
Download
If you don't know what to do with many of thepapers piled on your desk, stick a dozen colleagues' initials on'em, and pass them along. When in doubt, route. — Malcolm Forbes
Reference implementation
Stable tarballs of babeld are availablein my download area.
You can get my latest(possibly unstable) sources using git:
git clone git://github.com/jech/babeld.git
Soulver 2 7 1. Debian and Ubuntu packages should be available in your favouriterepository (merci, Stéphane !).
apt-get install babeld
Versions are also included in Fedora Extras and ArchLinux. On other Linux and BSD systems (includingMac OS X), building the daemon is a simple matterof
make && make install
.Babel: Choice 1 0 3
Other implementations
Babel: Choice 1 0 Percent
There exist other implementations of the Babel protocol:
Babel: Choice 1 0 1
- Bird includes acomplete and competent independent reimplementation of Babel.
- FRR (the successor to Quagga)includes an implementation of Babel based on the babeldimplementation. This version is currently obsolete, and not recommended.
- Pybabel is anindependent reimplementation of Babel in Python, due to Markus Stenberg.It is a complete implementation of the IPv6 subset of RFC 6126, butwithout support for link quality estimation. It is not recommended exceptin small wired networks.
- Sbabeld is a minimalistic stub-only implementation of Babel that compiles to just 12kB on AMD 64.
- There exists an independent reimplementation of Babel for the OMNet++simulator, described in thispaper.
Related software
Babel: Choice 1 0 4
- Babelweb2 is a web interface for visualising Babel routes, fullybuzzword-compliant (Go, HTML5, Websockets, etc.).
- Tcpdump has had support for displaying Babel packets since version 4.2.1(tcpdump download).
- Wireshark has had support since version 1.7.0(Wireshark download).
- Babel-pinger, a hack to export a defaultroute into Babel for people using DHCP to configure their routers ratherthan speaking to their upstream provider with a proper routing protocol, is available in my download area.
- Shncpd is a configuration daemonthat, together with babeld, makes for a reasonably complete implementationof the IETF Homenet protocol suite. Work isongoing to determine if it is suitable for mesh networks.
- AHCP is a configuration protocol for mesh networks.