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75e0e026 PH |
1 | EXIM'S BEHAVIOUR CHANGES WHEN RUNNING IN THE TEST HARNESS |
2 | --------------------------------------------------------- | |
3 | ||
4 | When Exim is running in its test harness, via the scripts in the exim-testsuite | |
5 | distribution, its behaviour is altered in a few ways, in order to make the | |
6 | regression testing work properly. The documentation for the test suite | |
7 | describes how a copy of the Exim binary is taken and patched in order to get it | |
8 | to run in the test harness. This document briefly lists the behavioural changes | |
9 | that result. They come into play when the Boolean variable running_in_test_ | |
10 | harness is true. | |
11 | ||
12 | ||
13 | Privilege | |
14 | --------- | |
15 | ||
16 | Exim does not give up its root privilege when called with -C or -D, nor does it | |
17 | insist on the caller being an admin user when starting a daemon, a queue | |
18 | runner, or requesting debug output. | |
19 | ||
20 | ||
21 | Small Pauses | |
22 | ------------ | |
23 | ||
24 | In a number of places, typically when a subprocess has been forked, there are | |
25 | short pauses of half or one second in one of the processes. This allows the | |
26 | other process to "go first"; it ensures that debugging or logging output always | |
27 | appears in the same order. | |
28 | ||
29 | ||
30 | Daemon | |
31 | ------ | |
32 | ||
33 | The daemon always writes a pid file when running in the test harness. | |
34 | ||
35 | ||
36 | CRAM-MD5 | |
37 | -------- | |
38 | ||
39 | The cram_md5 authenticator always uses the same challenge string. | |
40 | ||
41 | ||
42 | Appendfile | |
43 | ---------- | |
44 | ||
45 | After a quota error, the "time since last read" for the file is forced to 10s, | |
46 | for repeatability. | |
47 | ||
48 | ||
49 | Memory management | |
50 | ----------------- | |
51 | ||
52 | Memory management debugging output contains only the store pool and the size | |
53 | (other information is too variable). New memory is initialized to contain F0 in | |
54 | all bytes. | |
55 | ||
56 | ||
57 | Queue running | |
58 | ------------- | |
59 | ||
60 | There's a facility (-Tqt) for fudging queue times for testing retry logic. | |
61 | ||
62 | ||
63 | Syslog | |
64 | ------ | |
65 | ||
66 | Exim never writes to syslog in the test harness. Attempts to do so are silently | |
67 | ignored. None of the tests actually specify syslog logging for any actual log | |
68 | lines, but there is one that tests the inability to open the main and panic | |
69 | logs, which by default then tries to write to syslog. | |
70 | ||
71 | ||
72 | SMTP connection timeout | |
73 | ----------------------- | |
74 | ||
75 | In order to be able to test timeout handling, a "connection refused" error is | |
76 | converted into a timeout if the timeout value is set to 999999s. | |
77 | ||
78 | ||
79 | Random numbers | |
80 | -------------- | |
81 | ||
82 | The seed for the pseudo-random number generator is set to a fixed value in the | |
83 | test harness, to ensure repeatability. | |
84 | ||
85 | ||
86 | Bounce messages | |
87 | --------------- | |
88 | ||
89 | When Exim is submitting a bounce message to itself, unless the configuration | |
90 | has set queue_only, it uses -odi so that the bounce is delivered before the | |
91 | subprocess returns. This avoids a race that might put log lines in an arbitrary | |
92 | order. | |
93 | ||
94 | ||
95 | DNS lookups | |
96 | ----------- | |
97 | ||
98 | The real DNS resolver is never called. Instead, a fake resolver, which runs as | |
99 | a separate program, is used. It is part of the test suite and is documented | |
100 | there. This ensures complete control over the exact results of any DNS lookups. | |
101 | ||
102 | An attempt to look up a PTR record for 99.99.99.99 or an IP address for a host | |
103 | whose name ends with .test.again.dns always yields a "try again" error. | |
104 | ||
105 | A fake function is called instead of gethostbyname(). It recognizes the name | |
106 | "manyhome.test.ex" and generates a humungous number of IP addresses. It also | |
107 | recognizes an unqualified "localhost" and forces it to the appropriate loopback | |
108 | address (IPv4 or IPv6, as required). IP addresses are treated as literals. For | |
109 | other names, it does a DNS lookup (which of course actually calls the fake | |
110 | resolver) to find the host name. | |
111 | ||
112 | ||
113 | User names | |
114 | ---------- | |
115 | ||
116 | If unknown_login is set, it forces the login name, thus overriding the actual | |
117 | login for the test suite caller. When this happens, unknown_username provides a | |
118 | user name if it is set; otherwise an empty string is used. | |
119 | ||
120 | ||
121 | Ident | |
122 | ----- | |
123 | ||
124 | If -bh is used and both the sending host port and the incoming interface port | |
125 | are supplied, an ident (RFC 1413) call is made for testing purposes. | |
126 | ||
127 | ||
128 | Debug output | |
129 | ------------ | |
130 | ||
131 | Debugging output from the function that waits for the clock to tick at an | |
132 | appropriate resolution (before completing the arrival of a message, for | |
133 | example) is suppressed because the fractions of seconds that it contains will | |
134 | never be repeatable. | |
135 | ||
136 | ||
137 | Philip Hazel | |
138 | 15 February 2006 |