Fix Failing Python Tests | Dataford Interview Questions

Given several Python classes/objects with failing tests, find which functions' tests fail, explain why, and fix them; then modify one function and write a new function.

Asked in the Karat technical screen, this task uses Wallet objects and a Ledger. Correct the existing state-update behavior, modify adjust, and add total_by_tier.

Contract

Implement run_cases(cases). Each case contains wallets with name, tier, and points, plus operations ["deposit"|"withdraw", name, amount]. Return one result per case with final balances and tier_totals.

Constraints

1 <= len(cases) <= 100
1 <= number of wallets in a case <= 1000
Wallet names are unique within a case
Wallet tiers are nonempty strings
Wallet points and operation amounts are nonnegative integers
Every withdrawal is valid and does not create a negative balance

Function Signature

def run_cases(cases):

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Problem