Tool-based testing for composited systems

A computer storage device having computer-executable instructions recorded thereon, the computer-executable instructions to configure a computer to perform acts comprising:

• forming a dedicated channel with a shared library for a desktop compositor;
• creating a render target after the dedicated channel has been formed;
• rendering primitives by adding nodes to a visual tree, where the render target acts as root of the visual tree;
• generating a graphics oracle to predict a rendering;
• comparing composition or rendering primitives against the generated graphics oracle based on at least a portion of the visual tree;
• and
• outputting error information if a result of the comparison is greater than a predefined threshold.

A method of testing composition and rendering primitives, the method performed at one or more processing devices, the method comprising:

• at a resource model,
• adding nodes to a visual tree;
• creating render data corresponding to each node;
• sending instructions for rendering primitives associated with the created render data;
• and
• at a tool component,
• defining composition and rendering properties of a shared library for a desktop compositor using an algebraic structure of tools and tool combinators and components of the visual tree;
• deriving resource models based on the defined composition and rendering properties;
• testing composition and rendering primitives by comparing the derived resource models to the composition and rendered primitives;
• forming an expected rendering using the derived resource models;
• comparing a difference between selected pixels of the expected rendering and an actual rendering associated with the rendered primitives;
• and
• outputting at least one of an error report or a bug report, if the compared difference is greater than a predefined threshold.