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.
The testnet block explorer and API for blockchain.info doesn't appear to be working at the time of writing (July 2021). It may get fixed but in the meantime or perhaps regardless blockstream.info can be used instead.
Yes. Blockchain.info has its own testnet service, Check this link https://testnet.blockchain.info/