assertion mode: fail and save reproducer if custom error is returned

[bsamuels453]

Right now we allow the user to configure what kinds of reverts will make Medusa identify a counterexample.

We should have support for custom errors as well, especially for when debugging reversion statistics.

[0xalpharush]

We need to update the assertion test config to allow users to supply error selectors and check for them in the assertion test case provider here

medusa/fuzzing/executiontracer/execution_trace.go

Lines 231 to 232 in 3beda5c

	// Try to unpack a custom Solidity error from the return values.
	matchedCustomError, unpackedCustomErrorArgs := abiutils.GetSolidityCustomRevertError(callFrame.CodeContractAbi, callFrame.ReturnError, callFrame.ReturnData)

medusa/fuzzing/test_case_assertion_provider.go

Lines 60 to 71 in 3beda5c

	methodId := contracts.GetContractMethodID(lastCall.Contract, lastCallMethod)
	// Check if we encountered an enabled panic code.
	// Try to unpack our error and return data for a panic code and verify that that panic code should be treated as a failing case.
	// Solidity >0.8.0 introduced asserts failing as reverts but with special return data. But we indicate we also
	// want to be backwards compatible with older Solidity which simply hit an invalid opcode and did not actually
	// have a panic code.
	lastExecutionResult := lastCall.ChainReference.MessageResults().ExecutionResult
	panicCode := abiutils.GetSolidityPanicCode(lastExecutionResult.Err, lastExecutionResult.ReturnData, true)
	failure := false
	if panicCode != nil {
	failure = encounteredAssertionFailure(panicCode.Uint64(), t.fuzzer.config.Fuzzing.Testing.AssertionTesting.PanicCodeConfig)

Until it is implemented, one can write a try-catch on the error selector and assert false