prego 0.20130116

Concepts

A ‘prego task’ is a set of assertions.

Three assertion checkers are available:

• task.assert_that, for single shot checking.

• task.wait_that, for polling recurrent checking.

• task.command, to run arbitrary shell command.

Subjects (and their associated assertions):

• File(path)

  • exists()

• File().content

  • all hamcrest string matchers (ie: contains_string)

• Variable

  • exists()

  • all hamcrest string matchers (ie: contains_string)

• Command

  • running()

  • exits_with(value)

  • killed_by(signal)

• Host(hostname)

  • listen_port(number, proto=’tcp’)

  • reachable()

Execution model

The context

The context is an object whose attributes may be automatically interpolated in command or filenames. Also it may be used to set default parameter values. If context.cwd is set, all commands in the same test will use that value as CWD (Current Working Directory) unless you define a different value as command() keyarg.

Examples

Testing a netcat server

import hamcrest
from prego import Task, TestCase, context, running
from prego.net import Host, localhost, listen_port

class NetTests(TestCase):
    def test_netcat(self):
        context.port = 2000
        server = Task(desc='ncat server', detach=True)
        server.assert_that(Package('nmap'), installed())
        server.assert_that(localhost,
                           hamcrest.is_not(listen_port(context.port)))
        cmd = server.command('ncat -l -p $port')
        server.assert_that(cmd.stdout.content,
                           hamcrest.contains_string('bye'))

        client = Task(desc='ncat client')
        client.wait_that(server, running())
        client.wait_that(localhost,
                         listen_port(context.port))
        client.command('ncat -c "echo bye" localhost $port')

This test may be executed using nosetest:

$ nosetests examples/netcat.py
.
----------------------------------------------------------------------
Ran 1 test in 1.414s

OK

But prego provides a wrapper (the prego command) that provide some interesting options:

$ prego +v examples/netcat.py
[II] ------  Net.test_netcat BEGIN
[II] [ ok ]   B.0 wait that A is running
[II] [ ok ]   A.0 assert that nmap package is installed
[II] [ ok ]   A.1 assert that localhost not port 2000/tcp to be open
[II] [fail]   B.1 wait that localhost port 2000/tcp to be open
[II] [ ok ]   B.1 wait that localhost port 2000/tcp to be open
[II] [ ok ]   A.2 Command 'ncat -l -p 2000' code (0:0) time 5:1.34
[II] [ ok ]   A.3 assert that command A.2 returncode to be 0
[II] [ ok ]   A.4 assert that command A.2 execution time to be a value less than <5>s
[II] [ ok ]   A.5 assert that File '/tmp/prego-david/389/A.2.out' content a string containing 'bye'
[II] [ OK ]   A   Task end - elapsed: 1.33s
[II] [ ok ]   B.2 Command 'ncat -c "echo bye" localhost 2000' code (0:0) time 5:1.37
[II] [ ok ]   B.3 assert that command B.2 returncode to be 0
[II] [ ok ]   B.4 assert that command B.2 execution time to be a value less than <5>s
[II] [ OK ]   B   Task end - elapsed: 1.25s
[II] [ OK ]  Net.test_netcat END
----------------------------------------------------------------------
Ran 1 test in 1.416s

OK

Testing google reachability

import hamcrest
from prego import TestCase, Task
from prego.net import Host, reachable

class GoogleTest(TestCase):
    def test_is_reachable(self):
        link = Task(desc="Is interface link up?")
        link.command('ip link | grep wlan0 | grep "state UP"')

        router = Task(desc="Is the local router reachable?")
        router.command("ping -c2 $(ip route | grep ^default | cut -d' ' -f 3)")

        for line in file('/etc/resolv.conf'):
            if line.startswith('nameserver'):
                server = line.split()[1]
                test = Task(desc="Is DNS server {0} reachable?".format(server))
                test.command('ping -c 2 {0}'.format(server))

        resolve = Task(desc="may google name be resolved?")
        resolve.command('host www.google.com')

        ping = Task(desc="Is google reachable?")
        ping.command('ping -c 1 www.google.com')
        ping.assert_that(Host('www.google.com'), reachable())
        ping.assert_that(Host('www.googlewrong.com'), hamcrest.is_not(reachable()))

        web = Task(desc="get index.html")
        cmd = web.command('wget http://www.google.com/webhp?hl=en -O-')
        web.assert_that(cmd.stdout.content,
                        hamcrest.contains_string('value="I\'m Feeling Lucky"'))