1 tdc - Linux Traffic Control (tc) unit testing suite 2 3 Author: Lucas Bates - lucasb@mojatatu.com 4 5 tdc is a Python script to load tc unit tests from a separate JSON file and 6 execute them inside a network namespace dedicated to the task. 7 8 9 REQUIREMENTS 10 ------------ 11 12 * Minimum Python version of 3.8. 13 14 * The kernel must have network namespace support if using nsPlugin 15 16 * The kernel must have veth support available, as a veth pair is created 17 prior to running the tests when using nsPlugin. 18 19 * The kernel must have the appropriate infrastructure enabled to run all tdc 20 unit tests. See the config file in this directory for minimum required 21 features. As new tests will be added, config options list will be updated. 22 23 * All tc-related features being tested must be built in or available as 24 modules. To check what is required in current setup run: 25 ./tdc.py -c 26 27 Note: 28 In the current release, tdc run will abort due to a failure in setup or 29 teardown commands - which includes not being able to run a test simply 30 because the kernel did not support a specific feature. (This will be 31 handled in a future version - the current workaround is to run the tests 32 on specific test categories that your kernel supports) 33 34 35 BEFORE YOU RUN 36 -------------- 37 38 The path to the tc executable that will be most commonly tested can be defined 39 in the tdc_config.py file. Find the 'TC' entry in the NAMES dictionary and 40 define the path. 41 42 If you need to test a different tc executable on the fly, you can do so by 43 using the -p option when running tdc: 44 ./tdc.py -p /path/to/tc 45 46 47 RUNNING TDC 48 ----------- 49 50 To use tdc, root privileges are required. This is because the 51 commands being tested must be run as root. The code that enforces 52 execution by root uid has been moved into a plugin (see PLUGIN 53 ARCHITECTURE, below). 54 55 Tests that use a network device should have nsPlugin.py listed as a 56 requirement for that test. nsPlugin executes all commands within a 57 network namespace and creates a veth pair which may be used in those test 58 cases. To disable execution within the namespace, pass the -N option 59 to tdc when starting a test run; the veth pair will still be created 60 by the plugin. 61 62 Running tdc without any arguments will run all tests. Refer to the section 63 on command line arguments for more information, or run: 64 ./tdc.py -h 65 66 tdc will list the test names as they are being run, and print a summary in 67 TAP (Test Anything Protocol) format when they are done. If tests fail, 68 output captured from the failing test will be printed immediately following 69 the failed test in the TAP output. 70 71 72 OVERVIEW OF TDC EXECUTION 73 ------------------------- 74 75 One run of tests is considered a "test suite" (this will be refined in the 76 future). A test suite has one or more test cases in it. 77 78 A test case has four stages: 79 80 - setup 81 - execute 82 - verify 83 - teardown 84 85 The setup and teardown stages can run zero or more commands. The setup 86 stage does some setup if the test needs it. The teardown stage undoes 87 the setup and returns the system to a "neutral" state so any other test 88 can be run next. These two stages require any commands run to return 89 success, but do not otherwise verify the results. 90 91 The execute and verify stages each run one command. The execute stage 92 tests the return code against one or more acceptable values. The 93 verify stage checks the return code for success, and also compares 94 the stdout with a regular expression. 95 96 Each of the commands in any stage will run in a shell instance. 97 98 Each test is an atomic unit. A test that for whatever reason spans multiple test 99 definitions is a bug. 100 101 A test that runs inside a namespace (requires "nsPlugin") will run in parallel 102 with other tests. 103 104 Tests that use netdevsim or don't run inside a namespace run serially with regards 105 to each other. 106 107 108 USER-DEFINED CONSTANTS 109 ---------------------- 110 111 The tdc_config.py file contains multiple values that can be altered to suit 112 your needs. Any value in the NAMES dictionary can be altered without affecting 113 the tests to be run. These values are used in the tc commands that will be 114 executed as part of the test. More will be added as test cases require. 115 116 Example: 117 $TC qdisc add dev $DEV1 ingress 118 119 The NAMES values are used to substitute into the commands in the test cases. 120 121 122 COMMAND LINE ARGUMENTS 123 ---------------------- 124 125 Run tdc.py -h to see the full list of available arguments. 126 127 PLUGIN ARCHITECTURE 128 ------------------- 129 130 There is now a plugin architecture, and some of the functionality that 131 was in the tdc.py script has been moved into the plugins. 132 133 The plugins are in the directory plugin-lib. The are executed from 134 directory plugins. Put symbolic links from plugins to plugin-lib, 135 and name them according to the order you want them to run. This is not 136 necessary if a test case being run requires a specific plugin to work. 137 138 Example: 139 140 bjb@bee:~/work/tc-testing$ ls -l plugins 141 total 4 142 lrwxrwxrwx 1 bjb bjb 27 Oct 4 16:12 10-rootPlugin.py -> ../plugin-lib/rootPlugin.py 143 lrwxrwxrwx 1 bjb bjb 25 Oct 12 17:55 20-nsPlugin.py -> ../plugin-lib/nsPlugin.py 144 -rwxr-xr-x 1 bjb bjb 0 Sep 29 15:56 __init__.py 145 146 The plugins are a subclass of TdcPlugin, defined in TdcPlugin.py and 147 must be called "SubPlugin" so tdc can find them. They are 148 distinguished from each other in the python program by their module 149 name. 150 151 This base class supplies "hooks" to run extra functions. These hooks are as follows: 152 153 pre- and post-suite 154 pre- and post-case 155 pre- and post-execute stage 156 adjust-command (runs in all stages and receives the stage name) 157 158 The pre-suite hook receives the number of tests and an array of test ids. 159 This allows you to dump out the list of skipped tests in the event of a 160 failure during setup or teardown stage. 161 162 The pre-case hook receives the ordinal number and test id of the current test. 163 164 The adjust-command hook receives the stage id (see list below) and the 165 full command to be executed. This allows for last-minute adjustment 166 of the command. 167 168 The stages are identified by the following strings: 169 170 - pre (pre-suite) 171 - setup 172 - command 173 - verify 174 - teardown 175 - post (post-suite) 176 177 178 To write a plugin, you need to inherit from TdcPlugin in 179 TdcPlugin.py. To use the plugin, you have to put the 180 implementation file in plugin-lib, and add a symbolic link to it from 181 plugins. It will be detected at run time and invoked at the 182 appropriate times. There are a few examples in the plugin-lib 183 directory: 184 185 - rootPlugin.py: 186 implements the enforcement of running as root 187 - nsPlugin.py: 188 sets up a network namespace and runs all commands in that namespace, 189 while also setting up dummy devices to be used in testing. 190 - valgrindPlugin.py 191 runs each command in the execute stage under valgrind, 192 and checks for leaks. 193 This plugin will output an extra test for each test in the test file, 194 one is the existing output as to whether the test passed or failed, 195 and the other is a test whether the command leaked memory or not. 196 (This one is a preliminary version, it may not work quite right yet, 197 but the overall template is there and it should only need tweaks.) 198 199 200 ACKNOWLEDGEMENTS 201 ---------------- 202 203 Thanks to: 204 205 Jamal Hadi Salim, for providing valuable test cases 206 Keara Leibovitz, who wrote the CLI test driver that I used as a base for the 207 first version of the tc testing suite. This work was presented at 208 Netdev 1.2 Tokyo in October 2016. 209 Samir Hussain, for providing help while I dove into Python for the first time 210 and being a second eye for this code.
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