Add unit tests for String and CompiledMethod codegen primitives (BT-2150)

[jamesc]

Summary

Closes BT-2150

string.rs and reflection.rs (CompiledMethod section) in crates/beamtalk-core/src/codegen/core_erlang/primitives/ were both severely under-tested. Coverage data from CI run 25428951201 showed:

• string.rs: 8.9% (14/145 lines) — only length and ++ exercised
• reflection.rs CompiledMethod: 0% — all 6 selectors uncovered

Changes

Adds 92 tests to the existing #[cfg(test)] mod tests block in primitives/mod.rs, following the exact pattern established by BT-2147 (Array + Dictionary):

• String transform (9 tests): at:, uppercase, lowercase, capitalize, trim, trimLeft, trimRight, reverse, , concat
• String search (17 tests): includes:, startsWith:, endsWith:, indexOf:, split:, splitOn:, repeat:, lines, words, replaceAll:with:, replaceFirst:with:, take:, drop:, padLeft:, padRight:, padLeft:with:, padRight:with:
• String misc (17 tests): isBlank, isDigit, isAlpha, asInteger, asFloat, asAtom, asList, each:, collect:, select:, reject:, stream, withAll:, fromCodePoint:, fromCodePoints:, fromIolist:, unknown→None
• String regex (7 tests): matchesRegex:, matchesRegex:options:, firstMatch:, allMatches:, replaceRegex:with:, replaceAllRegex:with:, splitRegex:
• String comparison (7 tests): =:=, /=, =/=, <, >, <=, >=
• CompiledMethod (7 tests): selector, source, doc, argumentCount, printString, asString, unknown→None

Zero production code changes. Primitives test count: 110 → 202.

Test plan

• cargo test -p beamtalk-core — 3411 tests pass (0 failed)
• cargo clippy -p beamtalk-core -- -D warnings — clean
• cargo fmt --check -p beamtalk-core — clean
• string.rs coverage expected to rise from 8.9% to ≥95%
• CompiledMethod coverage expected to rise from 0% to 100%

https://claude.ai/code/session_01T8TqFpxfyaJFntxm8GQG19

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Generated by Claude Code

Summary by CodeRabbit

• Tests
  • Significantly expanded unit test coverage for string primitives covering transforms, searches, comparisons, regex behavior, and miscellaneous selectors.
  • Added comprehensive tests validating compiler method selector outputs (including documented fields and argument handling) and preserved existing dictionary/unknown-selector test patterns.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: b6754a60-f942-4869-bf78-65c6bb992958

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Reviewing files that changed from the base of the PR and between 6748297 and dac32cd.

📒 Files selected for processing (1)

• crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs

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📝 Walkthrough

Walkthrough

This PR expands the unit test suite in crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs, adding extensive String primitive tests (transforms, search/split/replace, slicing/pad, misc, comparisons, regex) and CompiledMethod selector tests, plus preserved unknown-selector checks.

Changes

Core Erlang Primitives — Tests

Layer / File(s)	Summary
Transform-style String tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds tests for indexing (at:), case conversions (uppercase, lowercase, capitalize), trimming, reversing, and concatenation, asserting generated Core Erlang document strings or expected iolist/binary forms.
Search / Split / Replace tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds tests for includes:, startsWith:, endsWith:, indexOf:, split:, splitOn:, repeat:, lines, words, replaceAll, replaceFirst, asserting exact calls and option arrays where applicable.
Slicing / Padding tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds take:, drop:, padLeft/padRight, and padLeft:with:/padRight:with: tests, asserting usage of unicode:characters_to_binary around string/padding operations.
Misc / Iteration / Factory tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds isBlank, isDigit, isAlpha, asInteger, asFloat, asAtom, asList, each:, collect:, select:, reject:, stream, factory methods (withAll:, fromCodePoint:, fromCodePoints:, fromIolist:) tests and a String unknown-selector test.
Comparison operator tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds equality/inequality and ordering tests (=, /=, =:=, </>, <=/>=) asserting exact erlang comparison BIF calls in generated output.
Regex-related String tests (BT-709) crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds matchesRegex:, matchesRegex:options:, firstMatch:, allMatches:, replaceRegex:with:, replaceAllRegex:with:, splitRegex: tests asserting beamtalk_regex:* call forms and option handling.
CompiledMethod selector tests crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Adds tests asserting generate_primitive_bif emits beamtalk_compiled_method_ops:dispatch for selectors: selector, source, doc, argumentCount, printString, asString, plus an unknown-selector test expecting None.
Preserved Dictionary unknown-selector test crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs	Retains the existing Dictionary unknown-selector test asserting generate_primitive_bif returns None for unrecognized method names.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding unit tests for String and CompiledMethod codegen primitives, with specific ticket reference (BT-2150).
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch BT-2150-string-compiledmethod-codegen-tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs`:
- Around line 1061-1072: The tests like test_string_split (and similar tests at
ranges 1118-1144, 1172-1222, 1491-1554) only assert substrings and can miss
regressions; update these tests to assert the exact rendered Core Erlang output
instead of loose contains() checks: use
doc_to_string(generate_primitive_bif(...)) -> result.unwrap() and then
assert_eq!(output, "<expected full Core Erlang string>") (or at minimum assert
the exact call form and full argument order/token sequence, e.g. verify
"binary':'split'(..., 'global')" including Sep, order of arguments like 'Sep'
and any N/Pat/Repl parameters). Locate these cases around the
generate_primitive_bif/document rendering usages (e.g. test_string_split) and
replace the contains() assertions with assert_eq! or precise string
equality/assertions that include the full call shape.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: f2eb6188-3b3b-41c0-a347-b506ef8ad551

📥 Commits

Reviewing files that changed from the base of the PR and between 80cef8d and 6748297.

📒 Files selected for processing (1)

• crates/beamtalk-core/src/codegen/core_erlang/primitives/mod.rs

[Copilot]

Pull request overview

Adds substantial unit-test coverage for Core Erlang primitive codegen mappings for String and CompiledMethod within beamtalk-core, exercising many previously-uncovered selector→BIF/codegen paths.

Changes:

• Add a large suite of String primitive tests covering transform/search/misc/comparison/regex selector mappings.
• Add CompiledMethod primitive tests covering all supported selectors plus an unknown-selector None case.