🧪 Improve test coverage for get_char_column_simd

[bashandbone]

🎯 What: Missing tests for the SIMD-optimized character column calculation in crates/utils/src/simd.rs.

📊 Coverage: Added test cases for:

• Long UTF-8 and mixed strings to exercise SIMD chunking logic.
• Consecutive newlines and empty lines.
• UTF-8 characters crossing SIMD vector width boundaries (16, 32, 64 bytes).
• Newlines and multi-byte characters at the start of strings.
• Consistency checks between ASCII and UTF-8 paths.

✨ Result: Significant increase in test coverage and reliability for string processing utilities, ensuring robustness against boundary condition bugs in the SIMD implementation.

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PR created automatically by Jules for task 12491095417453404157 started by @bashandbone

Summary by Sourcery

Expand test coverage for SIMD-based character column calculation in string utilities.

Tests:

• Add tests covering long UTF-8 and mixed ASCII/UTF-8 strings to validate SIMD chunking behavior.
• Add tests for consecutive newlines and empty-line scenarios to ensure correct column reset logic.
• Add tests for UTF-8 characters positioned at typical SIMD width boundaries (16, 32, 64 bytes).
• Add tests for newlines and multi-byte UTF-8 characters at the start of strings to verify correct initial column handling.

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[sourcery-ai]

Reviewer's Guide

Adds focused unit tests for get_char_column_simd to improve coverage of UTF-8 handling, newline behavior, and SIMD boundary conditions without changing production code.

Sequence diagram for get_char_column_simd UTF-8 boundary test

sequenceDiagram
    actor TestRunner
    participant TestModule as GetCharColumnSimdTests
    participant UtilsSimd

    TestRunner->>TestModule: test_get_char_column_utf8_boundary()
    loop for width in [16, 32, 64]
        TestModule->>UtilsSimd: get_char_column_simd(text, width + 3)
        UtilsSimd-->>TestModule: column = width
        TestModule->>UtilsSimd: get_char_column_simd(text, width + 5)
        UtilsSimd-->>TestModule: column = width + 2
    end
    TestModule-->>TestRunner: assertions passed

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Class diagram for new get_char_column_simd tests

classDiagram
    class UtilsSimd {
        +get_char_column_simd(text: &str, offset: usize) usize
    }

    class GetCharColumnSimdTests {
        +test_get_char_column_long_utf8()
        +test_get_char_column_consecutive_newlines()
        +test_get_char_column_utf8_boundary()
        +test_get_char_column_newline_at_start()
        +test_get_char_column_utf8_at_start()
    }

    GetCharColumnSimdTests ..> UtilsSimd : uses

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File-Level Changes

Change	Details	Files
Add tests covering long UTF-8 and mixed ASCII/UTF-8 strings to exercise SIMD chunking behavior.	Add test that repeats a multi-byte emoji to validate character column computation at the end of long UTF-8 input. Add test that repeats a mixed ASCII-plus-emoji pattern to verify combined character counting across long inputs.	crates/utils/src/simd.rs
Add tests for newline edge cases including consecutive newlines and newline at the start of the string.	Add test verifying column resets correctly across consecutive newline characters and on subsequent non-newline characters. Add test verifying column calculation when the string starts with a newline and subsequent characters on the first non-empty line.	crates/utils/src/simd.rs
Add tests for UTF-8 characters positioned at SIMD-relevant byte boundaries.	Add parameterized test placing a multi-byte UTF-8 character so that it crosses 16, 32, and 64-byte boundaries and assert correct column for offsets after the character and into following ASCII text. Add test verifying correct column offsets when a multi-byte UTF-8 character appears at the start of the string followed by ASCII characters.	crates/utils/src/simd.rs

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[Copilot]

Pull request overview

This PR increases reliability of the SIMD-based get_char_column_simd utility by adding targeted tests that exercise UTF-8 handling and tricky boundary conditions in crates/utils.

Changes:

• Add long UTF-8 and mixed ASCII/UTF-8 test cases to better exercise chunked processing behavior.
• Add tests for consecutive newlines, newline-at-start, and UTF-8-at-start offsets.
• Add boundary-focused tests around common SIMD-width byte boundaries (16/32/64) to validate correctness when multi-byte characters straddle those boundaries.

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