NowChessSystems/docs/unresolved.md

[2026-04-06] FenParserFastParse: scoverage cannot reach 100% due to fastparse inline macro incompatibility

Requirement/Bug: 100% line/branch/method scoverage on FenParserFastParse.scala as specified in the coverage target.

Root Cause: fastparse 3.x uses Scala 3 inline macros for its parse(...) entry points. When scoverage instruments the compiled output, it generates synthetic proxy methods (e.g. parse0$proxy9, parse0$proxy10) from the macro expansion. These proxies are attributed to the source lines of the parser definitions but are never directly invoked at runtime — the actual execution goes through the inlined code paths. This results in 33% of statements being reported as uncovered despite all parser branches being exercised by the test suite.

Attempted Fixes: All six test cases (parseBoard valid, parseFen valid, reject invalid color/castling, importGameContext, reject malformed boards, reject overflow ranks) exercise every parser path. The issue is not in test coverage of logic but in how scoverage tracks inline-macro-generated bytecode. No source-level change can cause scoverage to instrument through inline expansion boundaries.

Next Step: Either accept the coverage gap for this file (it is an instrumentation artefact, not a logic gap) or replace the parse(...) call sites with a non-inline wrapper that shields the proxy generation from the coverage-instrumented compilation unit.