chapter_21

Exercises for Chapter 21

1. Add an error to dict.erl. Compile the module.

I have altered dict.erl so a certain line in it will cause it to crash. dict.erl is stored in the exercise_1/ directory.

2. Write a simple test module that calls dict in various ways to uncover the error.

Test module is in exercise_2/. In this directory, run:

erlc exercise_1/dict.erl exercise_2/dict_test.erl
erl

And then in the Erlang console run the tests:

dict_test:test().

3. Use the code coverage tool to see how many lines in the dict module are being executed by the test module.

The code coverage script is stored in the exercise_3 directory. To run the code coverage analysis compile the code and start an erl console:

erlc exercise_1/dict.erl exercise_2/dict_test.erl exercise_3/dict_test_coverage.erl
erl

And then in the Erlang console run the command to generate the code coverage results for the tests written in exercise 2:

dict_test_coverage:coverage().

4. Use the dbg module to find the error in the dict module

The dbg script is stored in the exercise_4 directory. To run the dbg tracing on the dict module compile the code and start an erl console:

erlc exercise_1/dict.erl exercise_2/dict_test.erl exercise_3/dict_test_coverage.erl
erl

And then in the Erlang console run:

dict_test_debug:trace().