Function Override

Force a contract function on your Stagenet to return a fixed value, without changing its code.

Use this to:

• Mock a price oracle, vault rate, or any external view function during testing.
• Force a contract into a specific branch (e.g. paused() = true) without writing to storage.
• Reproduce a production state that depends on a registry, ACL, or feed you can’t easily seed.

Targets your active stagenet — see Target a Stagenet. Backed by the function-override RPC methods.

function-override add

Install an override for a contract function.

contract.dev function-override add 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 \
  --abi 'function totalSupply() view returns (uint256)' \
  --returns '["1000000000000"]'

The same selector can have several overrides — one per --input-params set, plus an optional wildcard. Exact-input overrides take precedence over wildcards on the same selector.

Examples:

# Wildcard: every call to balanceOf returns 1,000,000 (6dp USDC)
contract.dev function-override add 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 \
  --abi 'function balanceOf(address) view returns (uint256)' \
  --returns '["1000000000000"]'
 
# Scoped: only this holder reads as 500
contract.dev function-override add 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48 \
  --abi 'function balanceOf(address) view returns (uint256)' \
  --input-params '["0x1111111111111111111111111111111111111111"]' \
  --returns '["500000000"]'
 
# Pretend the protocol is paused
contract.dev function-override add 0xVault... \
  --abi 'function paused() view returns (bool)' \
  --returns '["true"]'

Prints the created override id — keep it to update / disable / remove later.

function-override list

List active overrides.

contract.dev function-override list                       # every override
contract.dev function-override list --contract 0xVault... # one contract

Output is one override per line: <id> <contract> <enabled|disabled> returns=<json> [inputs=<json>].

function-override update

Replace the return values of an existing override. The contract address, selector, and inputParams are immutable — remove and re-add to change them.

contract.dev function-override update fov_abc123 --returns '["2000000000000"]'

function-override enable / disable

Toggle an override on or off without removing it. A disabled override persists but is not applied — calls fall through to the real contract.

contract.dev function-override disable fov_abc123
contract.dev function-override enable fov_abc123

function-override remove

Delete an override.

contract.dev function-override remove fov_abc123

Notes

• Overrides intercept at the EVM layer, so a contract that staticcalls the overridden function sees the override too — not just eth_call from outside.
• When both a wildcard and an exact-input override exist for the same selector, the exact-input one wins.
• See RPC → Function Overrides for the full RPC schema.