Announcing the Platåberget Testnet
tl;dr: Meet Platåberget: Glamsterdam's (Gloas + Amsterdam) early testing ground open to public participation. This upgrade comes with breaking changes for application developers. Notably, any tool that relies on a hardcapped maximum gas limit (think wallets, indexers and gas estimators) will break and needs to be updated. Please use this...
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A testnet announcement tells you that a chain exists for testing. It does not tell you what the chain is for, how durable it is, or whether anything you test there transfers to mainnet. This article sets out what to check in such an announcement and what the information is worth.
What a new testnet actually is
A separate chain with its own rules, funded by a team, with no economic significance. Testnet tokens have no value and no claim on anything. Holding testnet tokens is not holding anything.
A staging environment for specific features. Teams generally test the upgrades or applications they are about to ship. Anything not on the roadmap has no reason to be present, and its absence from the testnet is not evidence of anything.
Frequently temporary. Testnets are deprecated, reset, or abandoned. Anything you build against one can break without notice and without compensation.
What to check in the announcement
The chain ID and the RPC endpoints. A wrong chain ID in your configuration produces transactions on a different network than you intended, and testnets are where people most often leave mainnet credentials configured by accident. Check the chain ID against the published value, every time, rather than remembering it.
How testnet accounts are created. Whether faucet funds require a mainnet balance matters, because faucet requirements that are trivial today can become a barrier tomorrow, and some testnets deliberately gate access.
Which client software runs it and at what versions. A testnet running an unreleased client is a useful place to find problems, and a poor place to build anything.
Whether the team publishes a roadmap for the mainnet. A testnet with no stated mainnet plan is a research project, and treating it as a preview of a launch is speculation.
What testing on it can and cannot tell you
Use it for what it is good at: verifying that your contract deploys, that your transactions get included, and that your application’s behaviour matches your expectations under the new rules. Do not use it to estimate gas costs that will hold on mainnet, to test anything involving economic incentives, or to assume a state you observe will exist at launch.
The most common failure is treating testnet behaviour as a specification. If your application works on the testnet, you have learned that it works on the testnet.
Practical advice
Keep testnet configuration entirely separate from mainnet — separate wallet, separate saved notes, ideally a separate device or profile. Redeploy on mainnet from source rather than reusing the same deployment you tested. And if you find yourself keeping testnet tokens for any reason other than running a transaction, stop: there is no scenario where that is rational.