Mastering Modern Perl: Writing Efficient and Maintainable Code/

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Better Comparison and Organization of Tests

Better Comparison and Organization of Tests

Learn how to do better comparisons and organize tests.

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Better comparisons

Even though the heart of all automated testing is the boolean condition “is this true or false?” reducing everything to that boolean condition is tedious and produces awkward diagnostics. Test::More provides several other convenient assertion functions.

The is() function

The is() function compares two values using Perl’s eq operator. If the values are equal, the test passes:

use Test::More tests => 2;

is 4, 2 + 2, 'addition should work';
is 'pancake', 100, 'pancakes are numeric';

The first test passes and the second fails with a diagnostic message:

tests.t .. 1/2 
#   Failed test 'pancakes are numeric'
#   at is_tests.t line 4.
#          got: 'pancake'
#     expected: '100'
# Looks like you failed 1 test of 2.
Diagnostic message

Whereas ok() provides only the line number of the failing test, is() displays the expected and received values.

is() applies implicit scalar context to its values. This means, for example, that we can check the number of elements in an ...