test: add x/services simulation tests

[manu0466]

Description

Depends-On: #161
Closes: MILK-130

---

Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[manu0466]

When the simulation test starts, this invariant fails due to the presence of services while PoolHistoricalRewards is empty. I can't figure out how to resolve this issue properly. Any tips on how to address this would be greatly appreciated, @hallazzang.

[RiccardoM]

I guess this logic is incorrect: we should check

• the targets of pool delegations vs the pool historical rewards
• the targets of service delegation vs the service historical rewards
• the targets of operator delegations vs the operators historical rewards

But instead everything is checked against the pool historical rewards. Why is this the case @hallazzang?

[RiccardoM]

Also, if we need to make sure that there's an entry for each target, we should add a hook for AfterServiceCreated, AfterPoolCreated and AfterOperatorCreated to make sure that we create the first entry for each one of them there. Otherwise, inside a genesis file having some services but not yet delegations, this invariant might fail.

This is the same thing that the Cosmos SDK does:

func (h Hooks) AfterValidatorCreated(ctx context.Context, valAddr sdk.ValAddress) error {
	val, err := h.k.stakingKeeper.Validator(ctx, valAddr)
	if err != nil {
		return err
	}
	return h.k.initializeValidator(ctx, val)
}

I think we should have the same logic. Let me take care of adding this and fixing the invariant as well as adding unit tests.

[hallazzang]

But instead everything is checked against the pool historical rewards. Why is this the case @hallazzang?

Sorry guys this absolutely seems a bug 😅

Otherwise, inside a genesis file having some services but not yet delegations, this invariant might fail.

Oh that's also true. I don't know why the invariant wasn't broken already? FYI, in our code, we're initializing each delegation target when the first delegation is being created.

[RiccardoM]

I have now completely changed how this works. Instead of initializing the delegation target when a delegation is created, I have added some hooks to the x/pools, x/operators and x/services modules to make sure we initialize the x/rewards data when these are created.

I have also added some hooks to make sure we clear the store data when a service/operator is deleted (it was missing as well).

Finally, I fixed the invariant and added the missing unit tests to make sure it breaks only when expected.