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WRITING_TESTS.md

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Writing multi-node cloudfabric tests

Each test is a python class deriving from tailor.test.GenieTest. This class is a standard python unittest.TestCase, so the standard documentation applies. A good template to start from is:

class YourTest(GenieTest):
    """One line explaining what your test does!"""
    def setUp(self):
        if len(self.hosts.hosts) < 2:
            self.skipTest("Insufficient Hosts")
        super(YourTest, self).setUp()
        self.master = self.hosts.hosts[0]
        self.slave = self.hosts.hosts[1]
        self.assertSqlSuccess("DROP TABLE IF EXISTS t1;", self.master, database='test')

    def runTest(self):
        self.assertSqlSuccess("CREATE TABLE t1 (c1 INT AUTO_INCREMENT PRIMARY KEY, c2 INT) ENGINE=GenieDB;", hosts=self.master, database='test')

    def tearDown(self):
        self.runSql("DROP TABLE t1;", self.master, database='test')
        super(YourTest,self).tearDown()

This provides a few common features:

  • It ensure the test is run with at least two hosts
  • It sets up self.master and self.slave as aliases we can use to refer to particular hosts. This is useful as some commands, like CREATE TABLE should only be run on one host.
  • It provides an example of creating a table, including how we must ensure in the setUp that the table doesn't already exist, and cleaning up in the tearDown.

Like any python unittest test, we write the body of the test in the runTest function. The actual testing is done by calling assertion functions. In addition to the usual python assertions such as assertEqual and assertTrue, GenieTest provides:

  • assertSqlSuccess(query, hosts=None, database="")

    This function runs the SQL query query on several hosts, and asserts that no error occurs. If hosts is unspecified, the query is run on all known hosts, otherwise it can point to a Host object or list of Host objects.

  • assertSqlFailure(query, hosts=None, database="")

    This function does exactly as assertSqlSuccess, except that it asserts that an error does occur.

  • assertSqlSame(query, hosts=None, database="", force=False)

    This function operates as assertSqlSuccess, except that it additionally checks that all the hosts returned the same result. If force=True is given then no assertion occurs on Sql failure, but the result is still checked.

  • assertSqlEqual(query, expected, hosts=None, database, force=False)

    This function operates as assertSqlSame, except that it additionally checks that the output returned by the hosts matches expected.

  • assertScriptSuccess(script, hosts=None)

    This function executes the shell script given by script on several hosts, and asserts that the script returns code 0. hosts is interpreted as with the above functions.

  • assertScriptSuccess(script, hosts=None)

    This function does exactly as assertScriptSuccess, except that it asserts that an error does occur.

  • assertScriptSame(script, hosts)

    This function operates as assertScriptSuccess, except that it additionally checks that all the hosts return the same result.

  • assertScriptEqual(script, expected, hosts)

    This function operates as assertScriptSame, except that it additionally checks that the output returned by the hosts matches expected.

GenieTest also provides several functions that are not assertions, but are vital in constructing powerful tests:

  • runSql(query, host=None, database="", force=False)

    This function runs the SQL statements query on the given host. If host is not given, it defaults to the first host. If force=True, execution does not stop if a statement has an error.

    This function returns a tuple of the SQL result and a return code (0 for success).

  • runScript(script, host=None)

    This function runs the shell script script on the given host. If host is not given, it defaults to the first host.

    This function returns a tuple of the script output and return code.

  • partition(partitioned_hosts)

    This function introduces a network split between the hosts in partitioned_hosts and those not in it (the split is symmetric). A single Host or a list of Hosts may be given.

    Only one partition at a time is allowed.

  • unpartition()

    This function restores any previously introduced partition. This function is automatically called on tearDown().

  • setHostDelay(hosts=None, delay=100)

    This function makes all network data sent from hosts (which may be None, for all hosts, a particular Host or a list of hosts) delayed by delay milliseconds before going over the network.

    The same host may have setHostDelay called several times, and the last value will be used.

  • clearHostDelay(hosts=None)

    This function removes any network delay introduced by setHostDelay. hosts may be None, in which case all hosts have their delay cleared, or a Host object or a list of Host objects. This function is automatically called on tearDown().