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The source code contains four tests。 Each calls the method TranslateHello（） with some
input and receives the output。 The test happens when the output is verified against an expected
result。 The verification tests use the pareTo（） function to test for correct translation。
Notice the third test：
If （Translator。TranslateHello（〃allosss〃）。pareTo（〃〃） 0） Then
Console。WriteLine（〃Verify nontranslated word test failed〃）
End If
This test expects an explicit failure。 You need to write tests that expect to fail。 Successful
tests that are meant to fail ensure that your code does not generate false positives。 A false positive is
when your code is supposed to fail and it does not。
The tests are within a method that needs to be called from the Main（） method； as in the
following example：
Sub Main（）
TestTranslateHello（）
Console。ReadKey（）
End Sub
If you pile and run the tests； you will find that one of the tests fails。 The failing test is
the fourth one； which attempts to translate a word that has whitespace。 Whitespace is space
that we humans don’t notice； but is necessary to distinguish words； sentences； and so on。 Before
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CH AP T E R 3 ■ L E AR N IN G AB O U T ST R I N G M A N I PU L A TI O N S 55
we can solve the whitespace problem； we need to determine which part of the application is
not working properly。
Answering the Question of Responsibility
The whitespace problem is an interesting one。 The caller explicitly put in the extra spaces； but
is the whitespace a bug； or is it data that is passed in incorrectly？
The problem can be defined in the context of reasonable usage。 Imagine that you’ve just
bought a car and you’re driving it on the highway。 If the car breaks down； the warranty will be
in effect and cover the costs of the car repair。 Now imagine the situation where you think you
are one of the Dukes from the Dukes of Hazzard。 And being a Duke； you drive your new car as
fast as you can and then perform a flying jump。 The car will jump into air； which looks quite
spectacular； but then the car lands。 After that； the shocks collapse； and the car cannot be driven
any further。 Even though the car is brand new； the Duke did not use the car as envisioned by
the car manufacturer； and thus invalidates the warranty。
Getting back to the translation ponent； it exposes the method TranslateHello（） and
has responsibilities。 And the caller of TranslateHello（） has the responsibility of being reason
able about what can be expected to be translated。 So； is whitespace sent by the caller reasonable？
If the whitespace is a normal circumstance； then the failed test is a bug in the ponent。
But if the whitespace is not a normal circumstance； the caller is wrong and must be fixed。 The
answer is that the caller is being reasonable； and the ponent is not acting properly。 We
have a bug in the ponent that needs to be fixed。 How do I know that the caller is not being
reasonable？ I made it up； because that is how I expected the contract to be implemented。 The
key is in defining a good contract。
The bug in the ponent relates to the problem of how a word is being translated。 We
used the pareTo（） method； which means that each character is pared； position for
position。 The test failed because the caller passed in a string with whitespace； and the ponent
expected no whitespace。 This bug is not a surprise； because we humans ignore the whitespace； but
puters cannot。
Before I explain how to fix the bug； I need to take a step back and talk about what a string
is and how you can figure out what a string can do。
Investigating the String Type
String is a class type； and thus a reference type。 String is a type that has methods and proper
ties。 Value types like Double and Integer have methods and properties； but String is the first
type you are encountering that is a class in its own right （Double and Integer are not actually
classes）。
To investigate a type； you can read the documentation； or you can use IntelliSense。 Reading
the documentation is not a bad idea； but it is the slowest and most cumbersome。 IntelliSense
is an IDE approach； in which a defined type’s methods and properties are presented to you in
an easy…to…prehend manner。
The first time you use IntelliSense； it can be nerve…racking； because it seems like the IDE
has a life of its own。 There is a convention on how to use IntelliSense； as illustrated in Figure 3…2。
I suggest that you take a few moments to experiment with it。 I also remend that you keep
IntelliSense active in Visual Basic Express。
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56 CH AP T E R 3 ■ L E A R N IN G AB OU T ST R I N G M A N I P U L AT IO N S
Figure 3…2。 Using IntelliSense on a String typed variable
IntelliSense works on only identified variables that have types。 In Figure 3…2； IntelliSense
worked because the IDE parsed the code and had the ability to read the metadata associated
with the type。 Metadata is data that describes your source code。 Whenever you define a class；
methods and properties are associated with it。 The method and property descriptions are
pieces of metadata that is displayed by IntelliSense。 One of the strengths of is that all
types have metadata。
The Basis of All Types： Object
By default； everything in is an object with a few basic properties and methods。 Four basic