Testing for ll3.pm
-------------------

Original Test Scripts for ll.pm 
By
Satanjeev Banerjee
bane0025@d.umn.edu
13th February, 2002

Modified for ll3 by 
Amruta Purandare
pura0010@d.umn.edu
1st November,2002

1. Introduction: 
----------------

We have tested ll3.pm, a component of Bigram Statistics Package version
0.5. File ll3.pm implements the log-likelihood measure of
association. Note that ll3.pm is not a program by itself, but is a
statistical library package that is plugged into statistic.pl. We test
here the features of ll3.pm by running statistic.pl.

Following is a description of the aspects of ll3.pm that we have
tested. We provide the scripts and files used for testing so that
later versions of ll3.pm can be tested for backward compatibility.


2. Phases of Testing: 
---------------------

We have divided the testing into two main phases: 

Phase 1: Testing ll3.pm's response to erroneous conditions. 
Phase 2: Testing ll3.pm's behaviour under normal conditions. 


2.1. Phase 1: Testing ll.pm's response to erroneous conditions:
----------------------------------------------------------------------

The script for this phase is 'error-handling.sh'. To run the tests
contained in this script, type "error-handling.sh" at the command
prompt. 

This script performs several subtests: 

2.1.1. Subtest 1: 
-----------------

Ll3.pm is meant only for trigrams. This test checks if ll3.pm throws
an error when provided with larger n-grams.

2.1.2. Subtest 2: 
-----------------

Ll3.pm requires 7 frequency values: the frequency of the trigram,
and the 6 marginal totals. If these are not provided, ll3.pm should throw 
an error. This test checks for this error. 

2.1.3. Subtest 3: 
-----------------

The total number of trigrams in the file should be 1 or more. This test
checks if ll3.pm does indeed throw an error when passed a total
trigrams value that is less than or equal to zero.

2.1.4. Subtest 4: 
-----------------

The numbers passed to ll3.pm should be "valid" in that they should
represent a possible 3 D table. If this is not the case,
various warnings are thrown by ll3.pm. This test checks for these
warnings. 

Following is the input file, test-1.sub-4.cnt: 

35
one<>two<>three<>-2 14 15 11 5 4 6
one<>two<>four<>38 14 13 19 4 7 7
two<>three<>one<>16 14 13 21 4 8 5
two<>three<>five<>4 16 13 23 4 9 11
two<>three<>four<>4 16 -13 23 4 9 11
two<>three<>four<>4 16 13 23 40 9 11

The first trigram should elicit a warning that a frequency value cannot be 
negative. The next trigram should elicit the warning that the frequency value 
(38) cannot exceed the total number of trigrams. The third trigram should
result in a warning that the frequency value of the trigram (10) cannot
exceed the marginal totals. The fourth trigram has no problems and should 
be calculated for. The fifth trigram must not have a negative value
for the marginal total, the sixth trigram has too large a marginal value since 
it exceeds the total number of trigrams.



2.2. Phase 2: Testing ll3.pm's behaviour under normal conditions:
------------------------------------------------------------------

The script for this phase is 'normal-handling.sh'. To run the tests
contained in this script, type "normal-handling.sh" at the command
prompt. 

This script performs a single subtest that checks two things: 

First, it checks if ll3.pm works when the frequencies are given in a
non default order. All three frequency values are required, however
they could be in any order. Subtest a checks to see what happens when
the frequencies are in the default order and subtest b checks the situation 
when they are in a different order. 

Second it checks the actual calculations of ll3.pm. The output target
files, test-2.sub-1-a.reqd and test-2.sub-1-b.reqd, have been checked
manually to see if the scores obtained are correct. 


3. Conclusions:
---------------

Statistical library package ll3.pm has been tested for erroneous
conditions and normal operations too. It works! These tests can be
used to check for backward compatibility of newer versions.