fix(string): split and then join should be identity

[peter-jerry-ye]

Fixes #2019

[peter-jerry-ye-code-review]

Simplified split logic removes edge case handling for empty views

Category
Correctness
Code Snippet
string/methods.mbt:664-670

• if view.is_empty() {
• IterContinue
• } else {
• yield_(view)
• }

• yield_(view)
  Recommendation
  The change is correct. Empty views should be included in split results for consistency.
  Reasoning
  The original code was inconsistent with common string splitting behavior. Including empty views makes the function behave more predictably, especially for cases with trailing separators or empty input strings.

Test cases should be grouped by behavior type

Category
Maintainability
Code Snippet
string/string_test.mbt:424-430, 512-518 (duplicated test blocks)
Recommendation
Consolidate duplicate test blocks and group related test cases together:

test "split empty string behavior" {
  inspect!("".split(""), content="[]")
  inspect!("".split("x"), content=#|[""])
}

Reasoning
The test file contains identical test blocks. Grouping related test cases improves readability and makes the test intentions clearer.

New split/join identity test improves behavior documentation

Category
Maintainability
Code Snippet
string/string_test.mbt:740-758
Recommendation
Add more test cases with other common separators (e.g., newlines, tabs) and document the expected invariant:

///| Split and join operations should preserve the original string
///| for any valid separator.
test "split and join should be identity" {
**Reasoning**
The new test suite is valuable as it documents an important invariant of the split/join operations. Adding more test cases and documentation would make the expected behavior even clearer.

</details>

[coveralls]

Pull Request Test Coverage Report for Build 6526

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.002%) to 92.734%

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Totals
Change from base Build 6521:	-0.002%
Covered Lines:	6126
Relevant Lines:	6606

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💛 - Coveralls

[tonyfettes]

LGTM