All MRs that add unit tests conflict with each other

[smcv]

To reproduce:

• Add a feature, write tests for it, and push a MR
• Add another feature, write tests for it, and push a MR

Expected result: maintainers can review and merge several features in one go

Actual result: each new test has to change the line that prints 1..50, so they all conflict

We could perhaps make this better with code like this?

# in libtest-code.sh

test_number=0

ok () {
    test_number=$(( test_number + 1 )
    echo "ok $test_number - $*"
}

done_testing () {
    echo "1..$test_number"
}

# in the test

reticulate splines
ok "can reticulate splines"

ponder meaning of existence
ok "implements basic philosophy"

done_testing

with the TAP output ending up like this:

ok 1 - can reticulate splines
ok 2 - implements basic philosophy
1..2

[smcv]

(This is the equivalent of ok and done_testing in Perl's Test module, which is where TAP comes from.)