Warning: this worked for me on macOS as of August 2017. Over time you can expect some/most/all of the information here to have changed.
There are several testnets, a number of them old/deprecated. The latest seem to be Kovan and Rinkeby. Kovan seems to work only with Parity while Rinkeby seems to work only with geth.
You will need to install geth first.
I mostly followed this guide.
I tried first the experimental light mode but I got errors, so I tried with the full mode. Not a big deal at this moment because the size on disk is below 1GB and it took around one hour to download/build with a 2011 macbook Air.
I prefer to make the data directory explicit (where the blockchain files will be stored), so I first create one on a disk of my choice. Also I will work from that directory, so I will assume all commands are entered from it.
$ mkdir /path/to/rinkeby
$ cd /path/to/rinkeby
intitalise with genesis block
$ curl -O https://www.rinkeby.io/rinkeby.json
$ geth --datadir=. init rinkeby.json
$ geth --networkid=4 --datadir=. --ethstats='yournode:Respect my email@example.com' --bootnodes=enode://firstname.lastname@example.org:30303?discport=30304 --cache=1024
Wait. You will see the INFO message "Block synchronisation started" then many INFO lines starting with "Imported...". Sync is in progress...
- Note the 1GB cache, you can use less or more depending on your available memory
- Network id 4 corresponds to the Rinkeby chain
- Blockchain data will be stored in geth/
Check blockchain sync progress
$ cd /path/to/rinkeby
$ geth attach ipc:geth.ipc
At the ">" prompt you can type, e.g.
You can double check you are seeing the right data progress by looking at the last block at www.rinkeby.io home page.
Note that the "NOTE...Importing..." messages include a number parameter which is the block being processed.
Getting free (worthless) ether for testing
Create a testing account
Create an account, enter password, get its address (account data will be saved to keystore/):
$ geth --datadir=. account new
That is the address I got. In order to use the faucet & get ether into this account, first create a github gist with just the hash in it (remember to prepend with "0x"). In my case:
Now use your gist URL in the faucet feature at www.rinkeby.io
I requested 3 ETH, then I searched etherscan with my address to verify I got them:
Next verification step would be to verify that locally we also get the correct balance.
We first verify it is taking the accounts we created (files in keystore/)
The first one (index 0) is the one I got my 3 ETH, let's see if they are on our local blockchain (balance for account 0):
Now we may keep using geth, or a wallet for a nice UI.