Simple NFT MONITOR Testsuite
============================

The purpose of this suite of tests is to assert correct 'nft monitor' output for
known input. The suite consists of the single shell script 'run-tests.sh' which
performs the tests and a number of test definition files in 'testcases/'. The
latter have to be suffixed '.t' in order to be recognized as such.

Test Case Syntax
----------------

Each testcase defines a number of commands to pass on to 'nft' binary and an
associated 'nft monitor' output definition. Prerequisites for each command have
to be established manually, i.e. in order to test monitor output when adding a
chain, the table containing it has to be created first. In between each
testcase, rule set is flushed completely.

Input lines are prefixed by 'I'. Multiple consecutive input lines are passed to
'nft' together, hence lead to a single transaction.

There are two types of output lines: Those for standard syntax, prefixed by 'O'
and those for JSON output, prefixed by 'J'. For standard syntax output lines,
there is a shortcut: If a line consists of 'O -' only, the test script uses all
previous input lines as expected output directly. Of course this is not
available for JSON output lines.

Empty lines and those starting with '#' are ignored.

Test Script Semantics
---------------------

The script iterates over all test case files, reading them line by line. It
assumes that sections of 'I' lines alternate with sections of 'O'/'J' lines.
After stripping the prefix, each line is appended to a temporary file. There are
separate files for input and output lines.

If a set of input and output lines is complete (i.e. upon encountering either a
new input line or end of file), a testrun is performed: 'nft monitor' is run in
background, redirecting the output into a third file. The input file is passed
to 'nft -f'. Finally 'nft monitor' is killed and it's output compared to the
output file created earlier. If the files differ, a unified diff is printed and
test execution aborts.

After each testrun, input and output files are cleared.

Note: Running 'nft monitor' in background is prone to race conditions. Hence
an artificial delay is introduced before calling 'nft -f' to allow for 'nft
monitor' to complete initialization and another one before comparing the output
to allow for 'nft monitor' to process the netlink events.

By default, only standard syntax is being tested for, i.e. 'J'-prefixed lines
are simply ignored. If JSON testing was requested (by passing '-j' flag to the
test script), 'O'-prefixed lines in turn are ignored.

There is one caveat with regards to JSON output: Since it always contains handle
properties (if the given object possesses such) which is supposed to be
arbitrary, there is a filter script which normalizes all handle values in
monitor output to zero before comparison. Therefore expected output must have
all handle properties present but with a value of zero.