Code Coverage

"Christo" is an open-source tool to dynamically and safely retrieve code-coverage in Squeak. It provides a simple user interface, hiding the complexity of dynamic analysis and offers many powerful extensions compared to ’standard’ code coverage tools.

Download / How to get Christo

  • Install by yourself:
    • Load the package "PackageLoader" from SqueakSource (
    • Run "CoverageLoader new loadAll" in a workspace ... This will interactively install Christo and all its dependencies into your image.
  • Download an all-inclusive image (running version, but likely not up-to-date)
  • Public sources on SqueakSource:
    • ""

Demo Stuff

Features of Version 0.1

  • Code Coverage
    • Flexible kernel
      • Exchanging analysis technology, default: ByteSurgeon
      • Collecting any kind of runtime data, for example senders, receivers, contex, arguments, ... default: senders/calls
    • Technology independence. Currently supported: ByteSurgeon, JMethods/Ast-Interpretation, MethodWrappers, ObjectsAsMethods
    • Method and sub-method coverage
    • Dynamic links between tests and sources
    • System coverage notification events
    • Persistent live-cache of dynamic data
    • Image-Safety, unsafe nodes don’t get method-wrapped
  • User Interface
    • Simple and intuitive browsers completely hiding the complexity of dynamic analysis
    • Coverage-Configurations to quickly change the scopes of coverage
    • Coloring of nodes, for example classes, methods, sub-method-nodes, ...
    • 1-click coverage
    • Tightly integrating unit testing, debugging, profiling and coverage
    • Additional actions to support testing, coverage, ...
  • Partial Ordering of Tests
    • Browser and Visualization using GraphViz and Mondrian
    • Graph/Image-Export for GraphViz
    • Complexity View for debugging purposes
    • Identification of the least/most abstract test
  • (beta) (Delta) Debugger
    • Kind of (delta) Debugger to more effectively and efficiently debug tests/sources
    • Multiple different strategies exists
  • (beta) Code Generation
    • Test-code generation based on coverage-analysis (templates only)
  • Visualization
    • Coverage and Partial Ordering of Tests
    • Various Visualizations to more effectively search for badly covered sources or complex/ abstract tests, ...
  • Seaside
    • Generation on Seaside-Server pages
    • Dynamically updating

Known Bugs of Version 0.1

  • Visualization-Scripts don’t work on all nodes -> Dictionary/Graph-Bug
  • AST/JMethods
    • Coloring of sub-method doesn’t work properly
    • block variables are not annotated
  • Changing Technology
    • producing empty/nil results
    • failing tests
  • MethodWrappers are broken in 3.9
    • Compilation of Methods
  • Install/Uninstall instrumentation bug
    • optimization had some very nasty side effects -> wrappers don’t work correctly, produce garbage in systemn dictionaries

Plans for future versions:

  • Complete refactoring of the coverage-kernel
    • Sub-method coverage as standard + coloring + dyn type information (args, ...)
    • Smaller, lightweight, get rid of some high level code/abstractions making the analysis slow
    • Full-tracing techs
    • Unification of nodes (clean-up)
    • Un-installation routines (fix and accelerate)
    • Improve safety, but base don technology, not global
    • Scoped Coverage
    • Gepetto 2 and Object Flow !!!
  • User Interface
    • Adapt to the latest OBs
    • Better, faster browsers (old OBs are slow!)
    • Better actions and visualizations (focus)
    • Even tighter integation into the coding/testing process
    • More interactivity/agility (browsers, visualizations, debugging, ...)
    • Enhance the cache with the graph-based dictionary
    • More transparency
  • Server-Processes
    • Seaside components, visualizaions
    • Ansync-Coverage / "Multithreaded" anaylsis (?)
  • Debugging
    • Enhancing the Delta Debugger, maybe implementing a real Delta Debugger
  • Partial-Ordering
    • Better graphs, Layouts, ...
  • Code Generation
    • Real code/test analysis and real code generation
  • Installation
    • simpler, more stable !!!


  • My Master Thesis ;) ...

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Last changed by admin on 21 April 2009