Lesson Two: Encapsulation and Unit Testing

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Lesson Two Encapsulation and Unit Testing
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Process1. Encapsulate ALL class variables2.
Setup unit test program 3. Unit test4.
Functionally test5. Perform Refactorings
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1. Encapsulate ALL class variables

1. Write get and set methods for ALL class
   variablesModify ALL references to class
   variables to use get and set methods.Test
   methods.

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Write getters and setters for all class variables
public int getComputerStatus ()
return computerStatus public Image
getUserImage ()return userImage public
boolean getFirst () return first public
Image getComputerImage () return
computerImage public void
setComputerStatus (int computerStatus)
this.computerStatus computerStatus
public void setUserImage (Image userImage)
this.userImage userImage public void
setFirst (boolean first) this.first first
public void setCommputerImage (Image
computerImage) this.computerImage
computerImage
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Perform Refactorings 1. Self encapsulating
field2. Encapsulate field3. Encapsulate
collection
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Self Encapsulating Field
Summary You are accessing a field directly,
but the coupling to the field is becoming
awkward. Create getting and setting methods for
fields and use ONLY those to access the field.
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Self Encapsulating Field Motivation Data
fields should always be declared as
private. Getter and Setter methods should be used
to access the data. Debate exist about using
getter and setter methods inside the class. I
recommend you use these at ALL times.
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Self Encapsulating Field Example class
IntRange private int _low, _high boolean
includes (int arg) return arg gt _low arg lt
_high void grow (int factor) _high
_high factor IntRange (int low, int high)
_low low _high high // end
IntRange
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Self Encapsulating Field Example class
IntRange private int _low, _high public
getLow() return _low public setLow (int
arg) _low arg public getHigh() return
_high public setHigh (int arg) _high
arg boolean includes (int arg) return arg
gt getLlow () arg lt getHigh() void grow
(int factor) getHigh() getHigh() factor
IntRange (int low, int high) _low
low _high high // end IntRange
Encapsulate and reference.
Leave initializations as direct.
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Self Encapsulating Field Mechanics create
a getter and setter method for the field find
references to field - replace with get and set
methods make field private compile and test
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Encapsulate Field
Summary There is a public field. Make it
private and provide accessors.
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Encapsulate Field Motivation Sharing data
reduces modularity of the program .
Encapsulation hides the data and adds accessors
to protect the data and program integrity.
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Encapsulate Field Example
public String _name private String
)name public String getName () return )name
public void setName (String arg) _name arg

Should be
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Encapsulate Field Mechanics create get
and set methods for the field find all clients
and change references declare field as
private compile and test.
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Encapsulate Collection
Summary A method returns a collection. Make
it return a read-only view and provide add/remove
methods.
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Encapsulate Collection Motivation A
collection needs the same modularization and
encapsulation that one class does. Add getter
and setter methods for the collection.
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Encapsulate Collection Example
class Course public course (String name,
boolean isAdvanced) public boolean
isAdvanced ( ) class Person
public Set getCourses() return _courses
public void setCourses (Set arg) _courses
arg private Set _courses
A person is taking a course
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Encapsulate Collection Example
Person kent new Person() Set s new
HashSet() s.add(new Course (Smalltalk
Programming, false)) s.add(new Course
(Appreciating Single Malts, true))
kent.setCourses(s) Assert.equals
(2,kent.getCourses().size()) Course refact
new Course (Refactoring, true)
kent.getCourses().add(refact)
kent.getCourses().add(new Course (Brutal
Sarcasm, false)) Assert.equals (4,
kent.getCourses().size())) kent.getCourses().r
emove (refact) Assert.equals
(3,kent.getCourses().size())
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Encapsulate Collection Example
Iterator iter person.getCourses().iterator(
) int Count 0 while (iter.hasNext((
Course each (Course) iter.next() if
(each.isAdvanced(( count // end while
A client that to know about courses might do this
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Encapsulate Collection Example
Class Person public void addCourse (Course
arg) _courses.add(arg) public void
removeCourse (Course arg) _courses.remove(arg)
private Set )courses new HashSet()
Create the modifiers for the collection
Initialize the field
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Encapsulate Collection Example
Class Person public void setCourses (Set
arg) Assert.isTrue()courses.isEmpty())
Iterator iter arg.iterator() while
(iter.hasNext()) addCourse ((Course)
iter.next())
Write the setter methods
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Encapsulate Collection Example
public void initialzeCourses (Set arg)
Assert.isTrue()courses.isEmpty()) Iterator
iter arg.iterator() while
(iter.hasNext()) addCourse ((Course)
iter.next()) public void initializeCourses
(Set arg) Assert.isTrue(_courses.isEmpty()
_courses.addAll(arg) // end initializeCourses
Rename the method for clarity
Initialize and remove loop
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Encapsulate Collection Example
Person kent new Person () Set a new
HashSet() s.add(new Course (Samlltalk
Programming, false)) s.add(new Course
(Appreciting Single Malts, true))
kent.initializeCourses(s) Person kent
new Person() kent.addCourse(new Course
(Samlltalk Programming, false))
kent.addCourse(new Course (Appreciating Single
Malts, true))
becomes
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Encapsulate Collection Example
kent.getCourses().add(new Course (Brutal
Sarcasm, false)) kent.addCourse(new Course
(Brutal Sarcasm, false)) public Set
getCourses() return Collections.unmodifiableSet
(_courses)
becomes
I can then check that it is not modified
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Encapsulate Collection Example
Iterator iter person.getCourses().iterator()
int count 0 while (iter.hasNext()
Course each (Course) iter.next() if
(each.isAdvanced()) count // end while
Now I can move the behavior to the class
This method is better placed in the person class
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Encapsulate Collection Example
class Person int numberOfAdvancedCourses()
Iterator iter getCourses().iterator()
int count 0 while (iter.hasNext()
Course each (Course) iter.next()
if (each.isAdvanced()) count //
end while // end numberOfAdvancedCourses
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Encapsulate Collection Example
Kent.getCourses().size()
Kent.numberOfCourses() Class Person
public int numberOfCourses() return
_courses.size()
Is more readable as
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Mechanics Add and add and remove
method initialize the field to an empty
collection find callers of set method modify
or call find all users of getter and modify
collection modify getter to return a read-only
view find all users of getter move to
host change name of current getter compile and
test
Encapsulate Collection
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// GETS AND SETS ADDED TO CODE
public int getComputerStatus () return
computerStatus public Image getUserImage
()return userImage public boolean getFirst
() return first public Image
getComputerImage () return computerImage
public void setComputerStatus (int
computerStatus) this.computerStatus
computerStatus public void setUserImage
(Image userImage) this.userImage
userImage public void setFirst (boolean
first) this.first first public void
setCommputerImage (Image computerImage)
this.computerImage computerImage

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In this lesson, we do not make gets and sets for
arrays or other collections. That is handled
later. But for all primitive variables, and
class instance variables we must change EVERY
access to these variables to gets and sets. Many
people say that you dont have to do this inside
the class but it is simply a barrier to good
method and class partitioning so we will change
every one. The problem is that some of the
variables are used as parameters passed into
methods and this must be addressed properly for
good scoping of variables.

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//METHODS that need changes in their access to
variables int bestMove(int computerStatus, int
userStatus) has parameters making them
local variables scoping? ok boolean
legalUserMove(int canidateMove) boolean
legalComputerMove() int gameStatus(int
computerStatus, int userStatus) public void
paint(Graphics g) // paint the screen public
void mouseReleased(MouseEvent e)

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//METHODS that need changes in their access to
variables computerStatus userStatus 0
BECOMES setComputerStatus(0) setUserStatus(0)
if ((userStatus computerStatus)
ENDINGSTATE) BECOMES if ((getUserStatus()
getComputerStatus()) ENDINGSTATE)
computerImage getImage(getCodeBase(),
"oimage.gif") BECOMES setComputerImage(getImage(g
etCodeBase(), "oimage.gif"))

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2. Setup Unit Test Program

1. Either implement J or N unit testing in Java or C
   sharp ORWrite your own unit testing
   program. 1) Divide your program into two
   programs a) One that executes b) One that
   contains all methods etc. 2) Write a program
   that uses your containing class methods
   unit by unit for tests.

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2. Setup Unit Test Program
Exec class
Your class
Makes an instance All code in constructor
needed To execute
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2. Setup Unit Test Program
Your class
Method addit (int a, int b)int return a b
Your test class
Method addit (int a, int b)int int a 4
int b 5 int answer super (a,b) if
answer ltgt 9 print Error in addit print
expected, 9 print received, answer
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2. Setup Unit Test Program
Exec class
Your test class
Makes an instance of the TEST CLASS Execute as
usual
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2. Setup Unit Test Program
Copy your program and call it xxxxTest extending
your class Take out any GUI stuff (not this
test) Here we are testing methods. What else to
do??????
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2. Setup Unit Test Program
Decide what you are going to test int
bestMove(int computerStatus, int userStatus)
boolean legalUserMove(int canidateMove)
boolean legalComputerMove() We will not test
since it is tested functionally public void
init() public void paint(Graphics g) //
paint the screen
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2. Setup Unit Test Program
We do need to test public void mouseReleased(Mouse
Event e) However we will have to separate
the GUI from the domain functionality
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2. Setup Unit Test Program
// user clicked applet // GUI code int x
e.getX() // get mouse x location int y
e.getY() // get mouse y location Needs to stay
in mouseReleased() since it is GUI
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// domain functionality and GUI switch
(gameStatus()) // determine status case
WIN case LOSE case STALEMATE
play(getCodeBase(), "audio/return.au")
computerStatus userStatus 0 if (first)
// reset first computerStatus 1 ltlt
(int)(Math.random() 9) // end if
first !first repaint() // GUI
controlling when to display // RED LINED code
NEEDS TO BE A METHOD TO TEST
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Make it a METHOD public void resetFirst()
if (getComputerFirst()) // reset who is
first setComputerStatus ( 1 ltlt
(int)(Math.random() 9)) // end if
setComputerFirst (!getComputerFirst())
// end resetStatus
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Call the METHOD Now this is all GUI code
switch (gameStatus()) // determine status
case WIN case LOSE case STALEMATE
play(getCodeBase(), "audio/return.au")
resetStatus() repaint() return //
end switch
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3. Unit test program shown
in the next slides 4.
Functionally test program
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UNIT methods to test int bestMove(int
computerStatus, int userStatus) boolean
legalComputerMove() boolean legalUserMove(int
canidateMove) int gameStatus( ) public void
resetFirst()
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FIRST METHOD TO TEST int bestMove(int
computerStatus, int userStatus) //
bestMove TEST 1 // test if can find best
strategic move 4th position //
bestMove TEST 2 // test if can find next best
strategic move 0th // bestMove TEST 3
// test if can block win // bestMove
TEST 4 // test if can take win
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FIRST METHOD TO TEST -- WRITE THE bestMove
test int bestMove(int computerStatus, int
userStatus) public int bestMove (int
computerStatus, int userStatus, int correctMove )
int tempBestMove super.bestMove (
computerStatus, userStatus) if
(tempBestMove correctMove)
System.out.print (" good ") else
System.out.print ("NOT good ")
System.out.print (" tempBestMove "
tempBestMove) System.out.print ("
correctMove " correctMove)
System.out.println (" userStatus "
getUserStatus () ) return tempBestMove
// end best move
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Add a variable of return type that is the CORRECT
return value
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FIRST METHOD TO TEST -- WRITE THE bestMove
test int bestMove(int computerStatus, int
userStatus) public int bestMove (int
computerStatus, int userStatus, int correctMove )
int tempBestMove super.bestMove (
computerStatus, userStatus) if
(tempBestMove correctMove)
System.out.print (" good ") else
System.out.print ("NOT good ")
System.out.print (" tempBestMove "
tempBestMove) System.out.print ("
correctMove " correctMove)
System.out.println (" userStatus "
getUserStatus () ) return tempBestMove
// end best move
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2
Add a statement to call the super.xxxx method for
testing
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FIRST METHOD TO TEST -- WRITE THE bestMove
test int bestMove(int computerStatus, int
userStatus) public int bestMove (int
computerStatus, int userStatus, int correctMove )
int tempBestMove super.bestMove (
computerStatus, userStatus) if
(tempBestMove correctMove)
System.out.print (" good ") else
System.out.print ("NOT good ")
System.out.print (" tempBestMove "
tempBestMove) System.out.print ("
correctMove " correctMove)
System.out.println (" userStatus "
getUserStatus () ) return tempBestMove
// end best move
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3
Add an IF statement to see if the returned value
is correct
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FIRST METHOD TO TEST -- WRITE THE bestMove test
method int bestMove(int computerStatus, int
userStatus) public int bestMove (int
computerStatus, int userStatus, int correctMove )
int tempBestMove super.bestMove (
computerStatus, userStatus) if
(tempBestMove correctMove)
System.out.print (" good ") else
System.out.print ("NOT good ")
System.out.print (" tempBestMove "
tempBestMove) System.out.print ("
correctMove " correctMove)
System.out.println (" userStatus "
getUserStatus () ) return tempBestMove
// end best move
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I like to print out pertinent values to allow
easy debugging.
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FIRST METHOD TO TEST -- NOW write the tests int
bestMove(int computerStatus, int userStatus)
public void testBestMove ()
System.out.println (" ") System.out.println
("testBestMove") // bestMove TEST 1 //
test if can find best strategic move 4th
position bestMove (0, 0 ( 1 ltlt 1) (1
ltlt 8), 4) // bestMove TEST 2 // test if
can find next best strategic move 0th
bestMove (0, 0 ( 1 ltlt 4), 0) //
bestMove TEST 3 // test if can block win
bestMove (0, 0( 1 ltlt 3)( 1 ltlt 4), 5)
// TEST 4 // test if can take win
bestMove (0 ( 1 ltlt 6)( 1 ltlt 7), 0( 1 ltlt 3)( 1
ltlt 4), 8) // end testBestMove
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FIRST METHOD TO TEST -- NOW run the tests int
bestMove(int computerStatus, int userStatus)
Place the test calls in the main or paint
method of the sub class public void
paint(Graphics g) testBestMove ()
testLegalComputerMove()
testLegalUserMove() testGameStatus(
) bestMove Test 1 good temp 4 correct
4 user 258
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// bestMove TEST 1 // test if can find best
strategic move bestMove (0, 0 ( 1
ltlt 1) (1 ltlt 8), 4) public int bestMove (int
computerStatus, int userStatus, int correctMove )
int tempBestMove super.bestMove (
computerStatus, userStatus) if
(tempBestMove correctMove)
System.out.print (" good ") else
System.out.print ("NOT good ")
System.out.print (" tempBestMove "
tempBestMove) System.out.print ("
correctMove " correctMove)
System.out.println (" userStatus "
getUserStatus () ) return tempBestMove
bestMove Test 1 good temp 4
correct 4 user 258 TEST 2, 3, 4 similar
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boolean legalUserMove(int legalComputerMove, int
legalUserMove, int canidateMove, boolean
correctAns) boolean tempLegalUserMove
super.legalUserMove (computerStatus,
userStatus, canidateMove) if(tempLegalUserMove
correctAns ) System.out.print ("good ")
else System.out.print ("NOT good ")
System.out.print (" computer "
computerStatus) System.out.print ("
user " userStatus) System.out.print
(" canidate " canidateMove)
System.out.print ( " userMove "
tempLegalUserMove) System.out.println ("
correctAns " correctAns) return
tempLegalUserMove // end legalUserMove
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// legalUserMove TEST 1 // test if within range
of squares userStatus 0 ( 1 ltlt 0)
computerStatus 0 ( 1 ltlt 2)
legalUserMove (computerStatus, userStatus, 9,
false) // TEST 1 // legalUserMove TEST
2 // test if empty false // legalUserMove TEST
3 // test if empty true legalUserrMove Test
1 good computer 4 user 1 canidate
9
userMove false correctAns
false
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boolean legalComputerMove (int
computerStatus, int userStatus, boolean
correctAns) boolean tempLegalComputerMove
super.legalComputerMove (computerStatus,
userStatus) if(tempLegalComputerMove
correctAns) System.out.print ("good
") else System.out.print ("NOT good ")
System.out.print (" computer "
computerStatus) System.out.print (" user
" userStatus) System.out.print ("
computerMove " tempLegalComputerMove)
System.out.println (" correctAns "
correctAns) return tempLegalComputerMove
// end tryLegalComputerMove
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// legalComputerMove TEST 1 // test if ending
state userStatus 0 ( 1 ltlt 0) (1 ltlt
1) (1 ltlt 3) (1 ltlt 5) (1 ltlt 8)
computerStatus 0 ( 1 ltlt 2) (1 ltlt 4) (1 ltlt
6) (1 ltlt 7) legalComputerMove
(computerStatus, userStatus, false) //
TEST 1 // legalComputerMove TEST 2 // test if
NOT in ending state legalComputerMove Test
1 good computer 212 user 299

computerMove false

correctAns false
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int gameStatus(int computerStatus, int
userStatus, int correctStatus) int
tempGameStatus super.gameStatus
(computerStatus, userStatus) if
(tempGameStatus correctStatus)
System.out.print ("good ") else
System.out.print ("NOT good ")
System.out.print (" computer "
computerStatus) System.out.print (" user
" userStatus) System.out.print ("
status " tempGameStatus)
System.out.println (" correctStatus "
correctStatus) return tempGameStatus
// end gameStatus
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void testGameStatus() // gameStatus TEST 1
// test if WIN userStatus 0 ( 1 ltlt 0)
computerStatus 0 (1 ltlt 3) (1 ltlt
4) (1 ltlt 5) gameStatus
(computerStatus, userStatus, WIN) //
TEST 1 // gameStatus TEST 2 // test if LOSE //
gameStatus TEST 3 // test if STALEMATE //
gameStatus TEST 4 // test if CONTINUE testGameSta
tus Test 1 good computer 56 user 1

status 1 correctStatus 1
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public boolean resetFirst (boolean
computerFirst, boolean correctFirst)
boolean tempResetFirst super.resetFirst
(computerFirst) if (tempResetFirst
correctFirst) System.out.print ("good ")
else System.out.print ("NOT good ")
System.out.print (" computer "
computerStatus) System.out.print ("
computerFirst " computerFirst)
System.out.print (" reset " tempResetFirst)
System.out.println (" correctFirst "
correctFirst) return tempResetFirst
// end resetFirst
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public void testResetFirst () // TEST
1 resetFirst ( false, true) //
TEST 2 resetFirst ( true, false)
// end resetFirst testResetForst Test 1
good computerfirst false
reset
true correct true
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NOW we have defined our functional test and our
unit testing Other refactorings we do will be
tested each time to assure we do not loose
functionality or correctness in our program.