Adds 5 invariant-level tests on top of #469's transforms:
- TestFixExportedMarkdownIdempotent — f(f(x)) == f(x) across rich
fixtures (kitchen sink, CJK, nested containers). Protects the core
round-trip promise from future transform interactions that rewrite
their own output.
- TestFixExportedMarkdownPreservesFencedCodeByteForByte — packs every
pipeline-touching shape into a fence and asserts byte-identical output.
Code samples must never be silently rewritten by a formatting pass.
- TestFixExportedMarkdownPreservesCRLF — CRLF input preserves line
endings AND still triggers transforms. Windows-authored markdown
should not be silently LF-normalized.
- TestFixExportedMarkdownTransformInteractions — composition regressions:
nested-list + trailing-space bold, text→list transition, callout
containing list with emphasis, heading vs paragraph bold.
- TestNormalizeNestedListIndentationDocumentedSkips — locks in the
deliberate no-op branches (odd-space indent, blank-line loose-list
sibling, 4-space indented code block, parentless two-space) as an
explicit spec so future heuristic tweaks surface in the test diff.
All transforms, fixtures, and expectations are derived from the head of
PR #469. No production code changes.
Co-authored-by: fangshuyu-768 <shuyufang768@outlook.com>
