# Coming up with an invariant

Ante Tests are single-failure tests of on-chain protocol **invariants**. Invariants should reflect fundamental guarantees that a protocol should satisfy.

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Take care when defining your project's invariants.

**Only define invariants you believe will never fail.**

It's the **guarantee** you are making and potentially **staking** ETH on**.**
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Here is an non-exhaustive list of invariants you might decide to write an Ante Test for (in no particular order):

* **"Rug" test** – check that contract-controlled assets are not drained
* **Plunge protection test** – check that contract assets do not drop below some threshold
* **Peg test** – check to see that two pegged assets stay pegged in price 
  * Note: in order to avoid flash loan manipulation of the Ante Test, this should be implemented against time-weighted average prices (TWAP) rather than spot prices
* **Solvency test** – Collateral asset value exceeds liabilities by some factor
* **Bonding curve test** – check that the bonding curve calculation (e.g. `x*y=k`) holds for an automated market maker (AMM) protocol
* **APY guarantee test** – check that actual rewards issued by a contract over a given time period exceeds the APY rate advertised by the protocol
* **DAO implementation test** – check that a proposal passed by a DAO was actually implemented
  * Checking outcomes can be tricky given the complexity and heterogeneity of outcomes. Defining a narrow test can help manage some of the complexity
  * Alternatively, this can be made generalized by having the DAO vote again on their satisfaction with the implementation outcome and having the Ante Test check the vote result
* **Access test** – check that funds can be withdrawn from contract in an expected manner
* **Market cap test** – check that the total value of contract assets exceeds some threshold
* **Volume test** – check that at least X unique wallets/transactions/etc. use a given protocol over a given time period

These are just some of the many possible Ante Tests that could be written. Happy writing!

Have an idea for a test? We'd love to hear about it! Message us on [Twitter](https://twitter.com/AnteFinance)/[Discord](https://discord.ante.finance/) or drop us a line at <hello@ante.finance>!