# M10-L02 — Lab contract

**Build:** Generate wrapper for ERC20 and call balanceOf.

**Pass:** Balance matches contract state; no gas is spent by caller for eth_call.

**Failure injection:** Confusing eth_call with a mined transaction causes bad UX.

**Review question:** Can eth_call still fail/revert?

Status: specification; only count as executable when source and tests are present and verified.