I'm trying to test to see if transactions went through or not and blockchain.info is super helpful for this on the real network.
Yes, blockchain.info has its own testnet service: https://testnet.blockchain.info/
www.blocktrail.com/tBTC now supports testnet too and has an API for it too (including wallet API)
Your could also use Biteasy.com Testnet Block Explorer which is pretty fast and also includes a REST API.
Blockr.io now also supports Bitcoin TESTNET
I might be a little late to the game here, but blockchain.info do offer testnet resources for SegWit2x. Go to https://testnet5.blockchain.info and you'll see an identical site to the original, but with testnet coins.
Coinprism.info has a testnet blockchain explorer. It does colored coins as well.
Note that the SSL certificate is self signed.
Yes. Blockchain.ino has its own testnet service, Check this link https://testnet.blockchain.info/