Regression Testing

February 4, 2025 ยท View on GitHub

The project counts with test packages that pixel-compare the actual output of the render with PNGs that were previously exported. If any pixel doesn't match with the expected output, the test fails. Browse subclasses of AePixelMatchTest to see them:

  • AeCairoRenderTest
  • AeCanvasTest
  • AeCairoConvertTest
  • AeCairoExamplesRenderTest
  • AeCairoMigratedRenderTest
  • AeCairoRecordingSurfaceRenderTest Such tests must be run in the Test Runner, because there is some hacky part that is not compatible with Calypso (the class browser).

Where are the PNGs?

Each test class defines methods that draw and return a AeCairoSurface or Form, and has an associated PNG (the expected result). Those PNGs are in the 'tests/' directory of this repo. A tricky part is how to locate the expected PNGs in the filesystem. To do it, the AeFilesystemResources will look into the registered Iceberg repositories for one named 'Alexandrie' (case-insensitive). This means that the test will ERROR if the repository is not registered at Iceberg. Normally the repository is registered after Metacello load.

CI jobs (smalltalk-ci via '.ci.ston') execute a pre-install script (located in the 'scripts/' directory) that registers the repository explicitly in Iceberg.

Steps to debug CI locally:

  1. cd to some tmp directory
  2. git clone https://github.com/pharo-graphics/Alexandrie.git && export GITHUB_WORKSPACE="$(pwd)/Alexandrie" && ~/d/pharo/smalltalkCI/bin/smalltalkci -s Pharo64-11 Alexandrie/.ci.ston