Object-Oriented Programming with Java, part I + II

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Authors: Arto Hellas, Matti Luukkainen
Translators to English: Emilia Hjelm, Alex H. Virtanen, Matti Luukkainen, Virpi Sumu, Birunthan Mohanathas, Etiënne Goossens
Extra material added by: Etiënne Goossens, Maurice Snoeren, Johan Talboom

The course is maintained by Technische Informatica Breda

Towards Automatic Tests

Testing a program manually is a hopeless burden. It is possible to automate inputs by setting up a string as a Scanner object parameter. The example below shows how it is possible to test automatically the program above.

String input = "translate\n" + "monkey\n"  +
                "translate\n" + "cheese\n" +
                "add\n"  + "cheese\n" + "juusto\n" +
                "translate\n" + "cheese\n" +
                "quit\n";

Scanner reader = new Scanner(input);
Dictionary dictionary = new Dictionary();

TextUserInterface ui = new TextUserInterface(reader, dictionary);
ui.start();

The print output contains only the program output, and not the user commands.

Commands:
  add - adds a word couple to the dictionary
  translate - asks for a word and prints its translation
  quit - stops the user interface

Command: Give word: Unknown word!

Command: Give word: Unknown word!

Command: In Finnish: Translation:
Command: Give word: Translation: juusto

Command: Cheers!

Giving a string to a Scanner class is a way to replace the String inputs given through the keyboard. The contents of the String variable input “simulates” the user input. \n denotes a line break. Each single part of the input variable which ends with a line break corresponds to one nextLine() input.

It is easy to change the text input, and we can add new words to our dictionary in the following way:

String input = "add\n"  + "cheese\n" + "juusto\n" +
                "add\n"  + "bier\n" + "olut\n" +
                "add\n"  + "book\n" + "kirja\n" +
                "add\n"  + "computer\n" + "tietokone\n" +
                "add\n"  + "auto\n" + "car\n" +
                "quit\n";

If you want to test again your program manually, change the Scanner object constructor parameter into System.in, i.e system input stream.

The program functionality must be checked from the output pane, still. The result can still be confusing at the beginning, because the automatic input does not appear in the output pane at all.

The final goal will be to also automate the testing the program’s functionality, so that both testing the program and analising its output text would happen successfully in one click.