Solidity – Using Modifiers in Foundry for Solidity Testing

foundrysoliditytesttesting

Is it a good practice to create modifiers in Foundry tests?

When testing cases, that share significant number of steps, but not that much that you want to create a separate testContract for them, with its own setUp(). (A simplistic situation could be testing a token contract where tests approve steps for testing allowance, transfer and other cases.)

I couldn't see any use of modifiers in examples linked by Foundry, so it raised this question: is it "safe" (in broad sense), is it a good practice at all?

Best Answer

It is safe to use modifiers in tests, but I cannot speak to whether it is good practice or not. It definitely does not seem to be common practice.

The main reason we have not used modifiers in example code is that it might seem a little opaque for example code, not because it won't work :)

Related Solutions

Solidity – How to Fund an Address in Foundry Test

For most such cases you need to find a vm function that does what you want. I recommend you check out this link. In this case it's vm.deal where you pass in the address as well as the amount of ether you want to give this address.

contract NFTCollectionTest is Test {
   ...
   function testMint() public {
      address someRandomUser = vm.addr(1);
      vm.prank(someRandomUser);
      vm.deal(someRandomUser, 1 ether);
      nftCollection.mint{value: 0.01 ether}();
      ...
   }
}

Foundry – How to Test if a Function Call Fails

I haven't used it specifically to test out of gas errors, but there are the expectRevert functions in forge-std/Vm.sol. Calling one of these functions will cause the vm to "catch" the revert in the following function call, and fail the test if the expected revert doesn't happen. The different variants of the function also allow you to assert that the error message is a certain value. Doing the following should work for you:

vm.expectRevert();
level20.withdraw{gas : 10000 wei}();

Best Answer

Related Solutions

Solidity – How to Fund an Address in Foundry Test

Foundry – How to Test if a Function Call Fails

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