Movie Store – Part 3

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Test-Driven Development: write tests before writing code.

Unit testing results in modular code. Modular code is:

• easy to test.
• immune to bugs.
• easy to understand.
• scalable.

Task 1: Unit Testing

1. Create a test that fails

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Write a unit test named sellMovieTest. Inside, sell The Godfather and check if the store still contains the movie. Hint: use assertFalse.

Inside Store.java, write code to make the test fail.

/**
 * Function name: sellMovie
 * @param name (String)
 * 
 * Inside the function:
 *    //nothing
 */

2. Make the test pass

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/**
 * Function name: sellMovie
 * @param name (String)
 * 
 * Inside the function:
 *   1. loop runs through the size of the ArrayList.
 *   2. removes the movie that matches the name passed in. 
 */

3. Refactor

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Can sellMovie be simpler?

Yes. removeIf is a better way to remove elements. It removes elements that "match a predicate". In other words, elements for which the returned boolean is true.

ArrayList.removeIf(Lambda Expression)

The lambda expression for removeIf:

1. receives each element as a parameter.
2. has an arrow that points to code.
3. returns a boolean.

Important: As you refactor, run the unit test to make sure there aren't bugs.

4. Refactor

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Can sellMovie be simpler?

• Yes. If the code is one line, you can omit the curly brackets and the return keyword. Java knows you intend to return a boolean.

Important: As you refactor, run the unit test to make sure there aren't bugs.

5. Refactor

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Can sellMovie be simpler? No. Refactoring complete.

Good Luck

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