Missing Test Suite integration for Batch Processing, Fee Mechanics, and Fuzz Testing

[aniket866]

1. testFailBatchTooLarge

• Why:? The contract has a limit of 50 invoices per batch (MAX_BATCH). We need a test that tries to send 51 invoices to confirm it fails (reverts) as expected.

2. testCreateInvoicesBatch

• Why?: The contract has a feature to send many invoices at once, but we never test if it actually creates them correctly in the array.

3. testPayInvoicesBatch

• Why:? Paying multiple invoices in one transaction involves complex math (summing totals). We need to verify that the total payment and fee calculations are exact.

4. testFuzz_CreateInvoice

• Why?: Our current tests only use "1 ether". We need "Fuzz Testing" to throw random numbers and weird addresses at the contract to ensure it doesn't break under unexpected inputs.

5. testWithdrawFees

• Why:? We are collecting fees, but we have no test to prove the owner can actually withdraw them. We must verify the treasury balance increases.

@kumawatkaran523 what's your view on this Please feel free to assign

[sach2004]

@DengreSarthak @kumawatkaran523 it is a valid and probably very important too. there are zero tests for batch create, batch pay, erc20 flow, fee withdrawal, admin functions. only 5 basic tests for a contract that handles real money