Debugging a VM error in solidity

Question

I'm getting the following error while running a test in truffle:

Error: Returned error: VM Exception while processing transaction: revert

Now, the code is simply to big and complicated to run through Stackoverflow. So my question instead is,

-How can I debug this? (more specifically: how can I get the VM logs and see exactly what is ducking up the test)

After a lot of trial and error I know exactly what function is misbehaving, I just don't know exactly what's misbehaving about it: here is the code in case it provides any clarity:

function onOCTReceived
(
 address operator, 
 address from, 
 uint256 amount, 
 bytes calldata data
) 
external 
returns
(
 bytes4
) 
{
    bobAndAlice(data);
    return (0x0);
}

important to note bobAndAlice(data) is working like a charm independently of the onOCTReceived() function so doubt the error is there, plus deleting it doesn't offer any more clarity on whats going on.

Edit: Additional testing shows that onOCTReceived() works perfectly fine in remix too.

Any pointers or help is very much appreciated.

Answer 1

When you call function bobAndAlice from the off-chain, the msg.sender that this function executes with is the address of the account which you have used for calling it.

When you call function bobAndAlice from the on-chain, the msg.sender that this function executes with is the address of the contract which you have used for calling it.

From your description, it sounds like this function performs some operation on msg.sender, which completes successfully when your account is used, but reverts when the contract is used.

It could be something as simple as require(someCondition(msg.sender)).

It could be something more complicated, for example, function bobAndAlice tries to send funds back to the caller (via msg.sender.transfer), but in the case of your contract, there is no fallback function to receive it, i.e., no implementation for function() external payable.

Without seeing the code of function bobAndAlice, it is rather impossible to tell...