Registering the generator

A job generator becomes active when a plugin registers it during collection. The YAML plugin does this by implementing the canary_collectstart hook:

@canary.hookimpl
def canary_collectstart(collector) -> None:
    collector.add_generator(YAMLTestGenerator)

At runtime, canary creates a collector and calls the canary_collectstart hook on all loaded plugins. The hook receives the collector object and can register one or more generators. From that point on, the collector will use the registered generators when scanning the filesystem.

Key idea

canary does not have a single built-in “test format”. A test source (.pyt, .vvt, YAML, CTest, etc.) is enabled when a plugin registers a generator.

Common failure mode

If YAML files are not being discovered, the first thing to check is whether the plugin package is installed and loaded. If the plugin is not loaded, its canary_collectstart hook is never called, and the generator is never registered.