Testing a Frontier

Frontier Tester is a helper class for easy frontier testing.

Basically it runs a fake crawl against a Frontier, crawl info is faked using a Graph Manager instance.

Creating a Frontier Tester

FrontierTester needs a Graph Manager and a FrontierManager instances:

>>> from frontera import FrontierManager, FrontierTester
>>> from frontera.utils import graphs
>>> graph = graphs.Manager('sqlite:///graph.db')  # Crawl fake data loading
>>> frontier = FrontierManager.from_settings()  # Create frontier from default settings
>>> tester = FrontierTester(frontier, graph)

Running a Test

The tester is now initialized, to run the test just call the method run:

>>> tester.run()

When run method is called the tester will:

  1. Add all the seeds from the graph.
  2. Ask the frontier about next pages.
  3. Fake page response and inform the frontier about page crawl and its links.

Steps 1 and 2 are repeated until crawl or frontier ends.

Once the test is finished, the crawling page sequence is available as a list of frontier Request objects.

Test Parameters

In some test cases you may want to add all graph pages as seeds, this can be done with the parameter add_all_pages:

>>> tester.run(add_all_pages=True)

Maximum number of returned pages per get_next_requests call can be set using frontier settings, but also can be modified when creating the FrontierTester with the max_next_pages argument:

>>> tester = FrontierTester(frontier, graph, max_next_pages=10)

An example of use

A working example using test data from graphs and basic backends:

from frontera import FrontierManager, Settings, FrontierTester, graphs

def test_backend(backend):
    # Graph
    graph = graphs.Manager()

    # Frontier
    settings = Settings()
    settings.BACKEND = backend
    settings.TEST_MODE = True
    frontier = FrontierManager.from_settings(settings)

    # Tester
    tester = FrontierTester(frontier, graph)

    # Show crawling sequence
    print '-'*40
    print frontier.backend.name
    print '-'*40
    for page in tester.sequence:
        print page.url

if __name__ == '__main__':