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Diffstat (limited to 'doc/doc-txt/test-harness.txt')
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diff --git a/doc/doc-txt/test-harness.txt b/doc/doc-txt/test-harness.txt new file mode 100644 index 000000000..9cfaf8b55 --- /dev/null +++ b/doc/doc-txt/test-harness.txt @@ -0,0 +1,140 @@ +$Cambridge: exim/doc/doc-txt/test-harness.txt,v 1.1 2006/02/16 10:05:33 ph10 Exp $ + +EXIM'S BEHAVIOUR CHANGES WHEN RUNNING IN THE TEST HARNESS +--------------------------------------------------------- + +When Exim is running in its test harness, via the scripts in the exim-testsuite +distribution, its behaviour is altered in a few ways, in order to make the +regression testing work properly. The documentation for the test suite +describes how a copy of the Exim binary is taken and patched in order to get it +to run in the test harness. This document briefly lists the behavioural changes +that result. They come into play when the Boolean variable running_in_test_ +harness is true. + + +Privilege +--------- + +Exim does not give up its root privilege when called with -C or -D, nor does it +insist on the caller being an admin user when starting a daemon, a queue +runner, or requesting debug output. + + +Small Pauses +------------ + +In a number of places, typically when a subprocess has been forked, there are +short pauses of half or one second in one of the processes. This allows the +other process to "go first"; it ensures that debugging or logging output always +appears in the same order. + + +Daemon +------ + +The daemon always writes a pid file when running in the test harness. + + +CRAM-MD5 +-------- + +The cram_md5 authenticator always uses the same challenge string. + + +Appendfile +---------- + +After a quota error, the "time since last read" for the file is forced to 10s, +for repeatability. + + +Memory management +----------------- + +Memory management debugging output contains only the store pool and the size +(other information is too variable). New memory is initialized to contain F0 in +all bytes. + + +Queue running +------------- + +There's a facility (-Tqt) for fudging queue times for testing retry logic. + + +Syslog +------ + +Exim never writes to syslog in the test harness. Attempts to do so are silently +ignored. None of the tests actually specify syslog logging for any actual log +lines, but there is one that tests the inability to open the main and panic +logs, which by default then tries to write to syslog. + + +SMTP connection timeout +----------------------- + +In order to be able to test timeout handling, a "connection refused" error is +converted into a timeout if the timeout value is set to 999999s. + + +Random numbers +-------------- + +The seed for the pseudo-random number generator is set to a fixed value in the +test harness, to ensure repeatability. + + +Bounce messages +--------------- + +When Exim is submitting a bounce message to itself, unless the configuration +has set queue_only, it uses -odi so that the bounce is delivered before the +subprocess returns. This avoids a race that might put log lines in an arbitrary +order. + + +DNS lookups +----------- + +The real DNS resolver is never called. Instead, a fake resolver, which runs as +a separate program, is used. It is part of the test suite and is documented +there. This ensures complete control over the exact results of any DNS lookups. + +An attempt to look up a PTR record for 99.99.99.99 or an IP address for a host +whose name ends with .test.again.dns always yields a "try again" error. + +A fake function is called instead of gethostbyname(). It recognizes the name +"manyhome.test.ex" and generates a humungous number of IP addresses. It also +recognizes an unqualified "localhost" and forces it to the appropriate loopback +address (IPv4 or IPv6, as required). IP addresses are treated as literals. For +other names, it does a DNS lookup (which of course actually calls the fake +resolver) to find the host name. + + +User names +---------- + +If unknown_login is set, it forces the login name, thus overriding the actual +login for the test suite caller. When this happens, unknown_username provides a +user name if it is set; otherwise an empty string is used. + + +Ident +----- + +If -bh is used and both the sending host port and the incoming interface port +are supplied, an ident (RFC 1413) call is made for testing purposes. + + +Debug output +------------ + +Debugging output from the function that waits for the clock to tick at an +appropriate resolution (before completing the arrival of a message, for +example) is suppressed because the fractions of seconds that it contains will +never be repeatable. + + +Philip Hazel +15 February 2006 |