Cover the core JSONL byte-level parser with targeted tests and a fuzz
harness to prevent regressions and catch panics on malformed input:
Unit tests:
- TestParseFile_UserMessages: verifies user message counting and
ProjectPath extraction from cwd field
- TestParseFile_AssistantDedup: confirms message-ID-based deduplication
where the last entry wins (handles edits/retries)
- TestParseFile_TimeRange: validates StartTime/EndTime tracking across
out-of-order timestamps
- TestParseFile_SystemDuration: tests turn_duration aggregation from
system entries (durationMs -> DurationSecs conversion)
- TestParseFile_EmptyFile: ensures zero stats without errors on empty input
- TestParseFile_MalformedLines: confirms graceful skip of unparseable
lines without aborting the entire file
- TestParseFile_CacheTokens: validates extraction of cache_read,
cache_creation_5m, and cache_creation_1h token fields
- TestExtractTopLevelType: table-driven tests for the byte-level type
extractor covering user, assistant, system, nested-type-ignored,
unknown, no-type, and empty cases
Fuzz test:
- FuzzExtractTopLevelType: seeds with realistic patterns plus edge cases
(unterminated strings, non-string type values, empty input). Asserts
the parser never panics and only returns known type strings or empty.
Uses a writeSession helper that creates temp JSONL files for each test,
keeping tests isolated and cleanup automatic via t.TempDir().
