Test case not working as expected: `nominators_also_get_slashed`

[maxsam4]

The intent of

substrate/frame/staking/src/tests.rs

Line 536 in 268450a

fn nominators_also_get_slashed() {

is to make sure that nominators also get slashed but in the test, nominator_slash is equal to 0 and the test is checking that a slash of 0 is applied which is equivalent of no slash at all.

In addition, the others vector in the validator's exposure is an empty array which suggests that no nominators are going to be slashed.

I'm not sure if it's just some misconfigured test case or a bug in the code but in any case, I don't think the test case is verifying what it was meant to verify.

[maxsam4]

One problem I see is that the test is nominating the controller key of the validator instead of the stash key. If I change it to nominate the stash key then the others vector in the validator's exposure is populated correctly. However, nominator_slash is still zero. If I increase the slash_fraction to 105% so that the slash is greater than the validator's exposure, even then the validator gets slashed for 100% of their exposure but the nominator's balance does not decrease (and the test starts failing).

Here are the changes that I mentioned above: maxsam4@84b756c

With 105% slashing, the validator loses 100% of their stake, and the nominator loses 0% (test fails).
At 5% slashing, the validator loses 5% of their stake and the nominator loses 0% (test passes but it shouldn't).

[bkchr]

CC @kianenigma

[kianenigma]

I haven't looked into it in detail but it could very well be the case. Many of the staking tests are

1. old
2. not correctly wired together
3. don't uphold ot their standard and similar to your example, even if their pre-condition is not met, the do not panic.

I'll take a look soon, thanks for raising it.

related: #5244

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In addition, the others vector in the validator's exposure is an empty array which suggests that no nominators are going to be slashed.

Yeah in this case nominators don't even exist to be slashed.

I'm not sure if it's just some misconfigured test case or a bug in the code but in any case, I don't think the test case is verifying what it was meant to verify.

Most likely just a misconfiguration.

[maxsam4]

Hey @kianenigma, did you get a chance to look at it?

[kianenigma]

Done, thanks for the reminder. Much needed 👍 .