Made for $work to explain unit tests to old time COBOLers.

1. Perl Testing 101
Craig Treptow, August, 2013

2. Unit Tests
Goal
Isolate each part of a program and show that
the individual parts are correct.

3. Unit Tests
Benefits
● Find problems earlier
● Facilitate code changes
○ Help ensure changes did not affect other behavior
● Makes integration testing easier
● Code becomes “self documenting”
○ Just look at the tests

4. Unit Tests
Reality
● They do not “prove” software is correct
● They can be
○ wrong
○ hard to set up
● They do
○ increase programmer confidence
○ need to be treated like “real code”

5. Perl Testing
What is test code?
It’s just Perl code:
#!/usr/bin/perl -w
print "1..1n";
print 1 + 1 == 2 ? "ok 1n" : "not ok 1n";
Since 1 + 1 is 2, it prints:
1..1
ok 1

6. Perl Testing
1..1
ok 1
This says:
● I’m going to run 1 test
● The test passed

7. Perl Testing
Writing that kind of code would get tedious.
So, start with Test::Simple:
#!/usr/bin/perl -w
use Test::Simple tests => 1;
ok( 1 + 1 == 2 );
That runs the same test as before.

8. Perl Testing
Want more tests?
#!/usr/bin/perl -w
use Test::Simple tests => 2;
ok( 1 + 1 == 2 );
ok( 2 + 2 == 5 );
Run the test:
perl simple.t
Produces:
1..2
ok 1
not ok 2
#
Failed test (test.pl at line 5)
# Looks like you failed 1 tests of 2.

9. Perl Testing
Before we go on:
a few conventions
● Test files are kept in folders called ‘t’
● Test files are named <something>.t
○ 00-<test prerequisites>.t
○ 10-<module name>.t
○ 20-<module name>.t
There aren’t “rules”, it’s Perl!!

10. Perl Testing
Test::Simple
● Only provides ok()
● Can be awkward
○ Can’t tell what you got for a result
○ Only True/False (ok/not ok)
There is hope...

11. Perl Testing
Test::More
● ok(), is(), isnt()
● like(), unlike()
● cmp_ok(), can_ok(), isa_ok()
● use_ok(), require_ok()
● is_deeply()
● eq_array(), eq_hash(), eq_set