TestingComparison.java

// Does it matter?

// Testing turnRight() this way tests the behavior in terms of
// another method on the same object.
// Possible problems:
// - We need to implement the other method first.
// - We need to call another method in order to verify that turnRight behaves correctly.

@Test
public void WhenTurningRight_IfPlaced_ShouldMoveInDirectionRightOfStartWhenMoved() {
    placeAtStartingPositionAndDirection(); // Assume starting direction is NORTH
    realToyRobot.turnRight();
    realToyRobot.move();
    verify(environment).moveIn(Direction.EAST);
}

// Compared to...

// Testing turnRight this way, makes it independent from move().
// It seems more focused. It has its own behavior instead of depending on move().
// Possible problems:
// - The first example tests the business logic:
// "Turning right from direction x implies moving will move in the direction to the right of x"
// This test doesn't reflect that.

@Test
public void WhenTurningRight_IfPlaced_ShouldTurnInClockwiseDirection() {
    placeAtStartingPositionAndDirection();  // Assume starting direction is NORTH
    realToyRobot.turnRight();
    verify(startingDirection).clockwise();
}