Challenge 1: A Basic Test File — Possible Solution
====================================================================

# t/strings.t (with the intentional failure, first version)
use strict;
use warnings;
use Test::More;

is("Hello" . " " . "World", "Hello World", 'concatenation works');
like("Hello World", qr/World/, 'regex match works');
is(1 + 1, 3, 'this assertion is intentionally wrong');

done_testing();

Running "prove t/strings.t" against this version shows:
not ok 3 - this assertion is intentionally wrong
#   Failed test 'this assertion is intentionally wrong'
#          got: '2'
#     expected: '3'
FAILED tests 3
Failed 1/3 subtests

# t/strings.t (corrected, failing assertion removed)
use strict;
use warnings;
use Test::More;

is("Hello" . " " . "World", "Hello World", 'concatenation works');
like("Hello World", qr/World/, 'regex match works');
is(2 + 2, 4, 'basic addition works');

done_testing();

Running "prove t/strings.t" against this version shows:
t/strings.t .. ok
All tests successful.

WHY THIS WORKS AS AN ANSWER
------------------------------
"Hello" . " " . "World" reuses string concatenation (Course 1,
Chapter 2) inside is(), reusing the chapter's own preference for is()
over a bare ok() specifically because it reports both the actual and
expected strings if they ever stop matching.

like("Hello World", qr/World/, ...) reuses the chapter's own like()
example directly, unchanged — a regex match assertion built on
Chapter 1/2's own m// and qr// syntax.

The intentionally-failing is(1 + 1, 3, ...) demonstrates exactly what
the chapter describes is() reporting on failure: both the "got" value
(2, what 1 + 1 actually evaluates to) and the "expected" value (3,
what the assertion claimed) are shown separately in the output —
directly observing the diagnostic benefit the chapter's own
explanation only described in words.

Removing that assertion and rerunning prove confirms all three
remaining tests pass, closing the loop from "see a failure" to "see
it fixed," which is the entire point of the exercise.