$($b$)$ Testing the Flight class $($use JUnit $4)$:

Once the Flight class has no compilation errors:

$$ Write the code for the JUnit test method testConstructor$()$ that tests the constructor

by providing it with valid arguments.

$$ Write a JUnit test method testInvalidConstructor$()$ that tests the constructor

with invalid arguments. The test should pass only if an IllegalArgumentException is thrown.

$$ Test the public methods that include all the getters, setters, the bookASeat$()$ method and the

toString$()$ method, using Junit.