All balance in --tx-in-collateral is taken. Change should go to --change-address (build command)

[CarlosLopezDeLara]

What - The user facing feature being implemented

When phase 2 validation fails and NO --tx-out-return-collateral is given, only exact amount of collateral should be used and change should be sent to --change-address specified in (cardano-cli transaction build)

Current behaviour is that it falls back to Alonzo-style of taking all collateral.

Steps to reproduce
Steps to reproduce the behavior:

1. Create a plutus script transaction that should fail phase2 validation
2. Give a --tx-in-collateral with more ADA than needed to cover the collateral
3. Do not give a --tx-out-return-collateral
4. Sign and submit the transaction
5. All the balance in -tx-in-collateral is taken

Why

Only the exact amount of collateral should be taken and change should be sent to --change-address when no --tx-out-return-collateral is given by the user.

Related GH issues

• [FR] - CLI build cmd to calculate return collateral value #3939

Personas - Who will this affect?

• SPO
• Dapp Devs
• Exchanges

Acceptance Criteria

Given that I'm a Dapp developer, when I submit a plutus script that fails phase 2 validation AND my transaction does not specify --tx-out-return-collateral I want:

• Only the exact collateral amount to be taken from --tx-in-collateral AND the excess is sent to --change-address

Definition of Done

• Code peer-reviewed
• Builds successfully on CI
• Includes documentation and/or examples for the functionality
• Log/record changes on Vnext (or similar depending on what we adopt)
• Acceptance Criteria met
• The new functionality is covered by dev/unit/property tests
• Merged to master
• Test Engineering Sign-off + E2E automated tests
• Released

[CarlosLopezDeLara]

Ledger to provide a helper function.

[Jimbo4350]

This is not a bug. We are getting too trigger happy with labeling things as bugs when they are feature requests!

[Jimbo4350]

One caveat is you also need to not provide the --tx-total-collateral flag in order to benefit from automatically calculating the return collateral. Specifying either --tx-total-collateral or --tx-total-collateral will result in the build command not automatically returning the "excess" collateral to your change address.