EnvironmentVariablesProvider: split(separator:) leads to inconsistent boolean array decoding between whitespace-only and empty elements

[Adobels]

In EnvironmentVariablesProvider.swift:347, array decoding relies on:

string.split(separator: separator).map { $0.trimmed() }

This approach leads to inconsistent behavior when parsing comma-separated values of whitespace-only or empty elements.

Current behavior

split(separator:) only creates elements when the element separated with separator is a one or more characters string. Empty string, two commas one after another, does not produces an empty element.
Additionally, trimmed() applied to a string containing only a space returns the string unchanged.

Examples:

• Input:
  "true, 1,,YES" → boolDecoder receives: [true, 1, YES]
• Input:
  "true, 1, , YES" → boolDecoder receives: [true, 1, , YES] -> This leads to a nil value during decoding. Currently protected by a guard, resulting in a throw

Additional observations

", ," .components(separatedBy: ",")   // count == 3
", ," .split(separator: ",")          // count == 1

components(separatedBy:) behaves more homogeneously for:

• empty strings
• strings containing only whitespace

This makes it more predictable when parsing arrays of strings that are expected to represent boolean values.

Proposed solution

Replace:

string.split(separator: separator)

with:
string.components(separatedBy: separator)

Impact / considerations

This change would affect all array decodings, not only booleans, analyze the impact across other array types handled by EnvironmentVariablesProvider

Reproduction

SwiftFiddle playground demonstrating the behavior:
https://swiftfiddle.com/vqjd6ajtfbchtb34hzejvnakiq

This issue is a follow-up to a discussion here: #120 (comment)

[Adobels]

I’m interested in working on this issue.

[czechboy0]

Thanks @Adobels - yeah I think parsing foo,,baz for all array types except string and bytes should fail due to the empty string in the middle, so: bool, double, int. I suspect we just need to pass omittingEmptySubsequences: false and then hopefully it'll throw an error correctly, as the parsing of the value will fail from the empty string.