doubly-linked-list: improve leak check #2043
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Previously the check may fail due to an underflow in the subtraction, rather than the assert. Forum discussion: https://forum.exercism.org/t/fix-operand-order-in-leaked-bytes-check-in-leak-test-doubly-linked-list-rust-exercise/15884
| let leaked_bytes = allocated_before - allocated_after; | ||
| assert!(leaked_bytes == 0); |
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Was there any particular reason for choosing subtraction over equality in the past? It seems like a really strange decision.
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Looking at it more closely, it just looks like a logic error. Even if there was a reason for the subtraction, the order should have been reversed. There's no conceivable reason for allocated_before to ever be larger than allocated_after.
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Original PR is here, I can't find any discussion on that.
| let leaked_bytes = allocated_before - allocated_after; | ||
| assert!(leaked_bytes == 0); |
There was a problem hiding this comment.
Looking at it more closely, it just looks like a logic error. Even if there was a reason for the subtraction, the order should have been reversed. There's no conceivable reason for allocated_before to ever be larger than allocated_after.
Previously the check may fail due to an underflow in the subtraction, rather than the assert.
Forum discussion:
https://forum.exercism.org/t/fix-operand-order-in-leaked-bytes-check-in-leak-test-doubly-linked-list-rust-exercise/15884