[ShadobaDev]

Summary

CI now builds and tests the project on MSVC, MinGW and Linux, and measures the library's test coverage on Linux. Covering the library found real bugs, fixed here. The coverage job now fails if a line goes uncovered or branches drop below 90%.

Library coverage (lib/src, lib/include, gcovr as CI runs it): lines 100% (3376), functions 100% (342), branches 95.1% (3727/3920). 429 tests pass on Linux, 393 on MinGW (one skipped: a Windows-only demonstration).

Bugs fixed

• render() with sliceHeight == 0 killed the caller's process. The slice count divided by zero (SIGFPE) before the height was checked. It now returns a typed SlicingFailed.
• An unpack that filled the disk reported success with the last file cut short: the stream was checked before it was closed. It is closed first now.
• WorkspacePackager::unpack() lost non-ASCII names in a process left in the "C" locale. It now unpacks in a UTF-8 locale on its own thread.
• A greyscale or grey+alpha overlay failed the whole render. It is converted to sRGB first, as pages are. A 16-bit overlay is scaled to 8 bits, not clipped.
• computeFileSha256() returned a hash of part of a file when a read stopped short, and an empty-data hash for a folder. Both now return empty ("cannot be read").
• Unchecked inputs:
  • MarginCropper refuses a negative margin and computes the safe area in 64 bits.
  • ScaledStrip::append() refuses a page of another width, a page with no image, and a strip taller than an int can count.
  • Scaler bounds targetWidth by VIPS_MAX_COORD.
• Failed saves left their temporary file behind. Five copies of "write a temporary file, then move it over the destination" are now one function, publishTempFile(), which always cleans up. The serializers also check for an error when closing the file.
• Grade neutrality compared doubles exactly. isNeutral() and the grade itself now accept a value within k_neutralTolerance (1e-6) of its neutral value. That is too little to move a 16-bit pixel. A slider value left a hair off its default, for example by arithmetic or a JSON round trip, now counts as untouched.

How coverage is held

• Failure paths: tests/lib-fault-tests/ (Linux only) makes any libvips, libarchive or C library function the library calls fail on demand, or return an image libvips never would. Every error path the library checks is tested this way.
• Dead code: code that cannot run was deleted, not excluded. Examples:
  • a self-check of a lookup that was already resolved;
  • preset filters on palettes that every setter keeps preset-free;
  • an empty-sink check on a sink that is never empty.
    Code that cannot be reached but has to stay carries a GCOVR_EXCL marker with its reason, and is listed in the wiki's Platform page.
• Why branches stop at 95%: what remains is what gcc counts and no test can take:
  • cleanup of temporaries on an exception's way out;
  • matching an exception's type in a catch;
  • guards of function-local statics;
  • the default of a switch that covers every enum value;
  • two states only another platform or a race reaches.
    The floor sits at 90% and is only raised.
• Docs: docs/CODING_STYLE.md says what new library code needs: a test, a fault wrapper, deletion, or a marker. docs/CHEATSHEET.md shows how to measure coverage locally, the same way CI does.

Also

• CI sends Linux coverage to Coveralls. The README shows CI, coverage, release and licence badges.
• The Release job takes its notes from the tag's section of docs/CHANGELOG.md.
• minipsd 0.4.1, whose plugin links into a shared library on Linux.