Testing Shill

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Introduction to shill testing

We test shill using unit tests and integration tests. The unit tests are built using Google Test and Google Mock. The integration tests use Tast and Autotest.

Running unit tests for Chrome OS

Shill unit tests are run just like any other unit test in the platform2 directory. See the platform2 unittest docs for more information.

Running integration tests

There are a variety of integration tests for shill, using either Tast or Autotest. WiFi autotests mostly require a special test AP setup (see Autotest wificell documentation).

Debug logs

Most networking-related daemons (including shill and its subprocesses) log to syslog, redirected to /var/log/net.log. Syslog prefixes log messages with the process name, so one can filter for shill, wpa_supplicant, etc., depending on what you're looking for.

Shill has many log severities, and they go to various places:

  • Critical messages (ERROR-level and higher) go to the main /var/log/messages as well as to net.log.
  • Informational messages (INFO and lower) go only to net.log.
  • VERBOSE messages (e.g., all those produced by SLOG()) are silent by default.

Verbose messages

In case you don‘t think shill’s logging is verbose enough already, there are plenty of more-verbose log messages that can be enabled dynamically.

Scopes: there a variety of component-specific scopes that can be enabled, like wifi, ethernet, or dbus. One can manipulate the current running instance of shill with the ff_debug tool. Settings do not survive daemon restart.

# Enable ethernet scope.
ff_debug +ethernet
# Disable dbus scope.
ff_debug -dbus
# List all valid scope tags.
ff_debug --list_valid_tags

Levels: by default, shill logs at level 0 (i.e., everything INFO or higher). Negative numbers represent VERBOSE (i.e., from SLOG()) levels.

# Enable SLOG(<tag>, 2) and SLOG(<tag>, 1) messages, if <tag> is in the enabled
# scopes list.
ff_debug --level -2
# Only log FATAL messages
ff_debug --level 4
# See ff_debug --help for more.

The shill upstart job also accepts a few environment variables, so you can see verbose messages even at startup:

# Stop shill and restart it with WiFi debugging at level -2.
stop shill; start shill SHILL_LOG_LEVEL=-2 SHILL_LOG_SCOPES=wifi

wpa_supplicant also has its own logging verbosity; shill will change this dynamically at times (e.g., when it thinks there are WiFi connection issues), but you can change these manually with the wpa_debug command. See wpa_debug --help for more info.

Note that integration tests may adjust logging verbosity automatically, depending on their needs.