Fix reverseChunked(by:) Method Implementation

[jiahan-wu]

Summary

This pull request is being made to resolve an inconsistency found in the reverseChunked(by:) method located within the Collection extension. The intended functionality of the method is to divide a collection into chunks of a given size, where, if the collection is not evenly divisible, the first chunk will be smaller. Instead of this expected behavior, the current implementation produces incorrect results, with the first chunk not being the smallest when required and subsequent chunks varying incorrectly in size.

Example

Here are concrete examples that demonstrate the problem with the reverseChunked(by:) method's current implementation:

Example 1:

let collection = "1234567898765"
let chunks = collection.reverseChunked(by: 4)

// Expected Chunks: ["1", "2345", "6789", "8765"]
// Actual Chunks:   ["1", "2345", "67898", "765"]

Example 2:

let collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17]
let chunks = collection.reverseChunked(by: 4)

// Expected Chunks: [[1], [2, 3, 4, 5], [6, 7, 8, 9], [10, 11, 12, 13], [14, 15, 16, 17]]
// Actual Chunks:   [[1], [2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15, 16, 17], []]

Impact of Changes

The changes introduced by this pull request will resolve the crashing issue in the PostgresNumeric(decimalString:) initializer. The crash is currently caused by the improper handling of string to numeric conversion when the string is split into chunks using the reverseChunked(by:) method.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.76%. Comparing base (43929b0) to head (6eb5201).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #465      +/-   ##
==========================================
- Coverage   61.78%   61.76%   -0.03%     
==========================================
  Files         125      125              
  Lines       10030    10024       -6     
==========================================
- Hits         6197     6191       -6     
  Misses       3833     3833              

Files	Coverage Δ
...ources/PostgresNIO/Data/PostgresData+Numeric.swift	70.50% <100.00%> (-0.86%)	⬇️

[gwynne]

At some point we should really just replace those methods altogether with an import of Algorithms and use of .chunks(ofCount:).reversed(), but for now this is fine.

[fabianfett]

@jiahan-wu Thanks for your contribution! Great fix!