Refactoring Encapsulation and Unit Testing Lesson Two: Encapsulation and Unit Testing

RefactoringEncapsulation and Unit Testing

Lesson Two: Encapsulation and Unit Testing


Process1. Encapsulate ALL class variables2. Setup unit test program 3. Unit test4. Functionally test5. Perform Refactorings


1. Encapsulate ALL class variables

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


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; }

Write getters and setters for all class variables


5. Perform Refactorings

1. Self encapsulating field2. Encapsulate field3. Encapsulate collection


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.

Self Encapsulating Field


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.


Self Encapsulating Field: Example:

class IntRange {

private int _low, _high;

boolean includes (int arg) { return arg >= _low ** arg <= _high; }

void grow (int factor) { _high = _high * factor; }

IntRange (int low, int high) {

_low = low;

_high = high;

} // end IntRange


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 >= getLlow () && arg <= 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.


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


Summary:

There is a public field.

Make it private and provide accessors.

Encapsulate Field


Encapsulate Field:

Motivation:

Sharing data reduces modularity of the program .

Encapsulation hides the data and adds accessors to protect the data and program integrity.


Encapsulate Field: Example:

public String _name;

private String )name;

public String getName () { return )name; }

public void setName (String arg) { _name = arg; }

Should be


Encapsulate Field:

Mechanics:

create get and set methods for the field

find all clients and change references

declare field as private

compile and test.


Summary:

A method returns a collection.

Make it return a read-only view and provide add/remove methods.

Encapsulate Collection


Encapsulate Collection:

Motivation:

A collection needs the same modularization and encapsulation that one class does.

Add getter and setter methods for the collection.


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



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().remove (refact);

Assert.equals (3,kent.getCourses().size());



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



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



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



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



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



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



Iterator iter = person.getCourses().iterator();

int count = 0;

while (iter.hasNext() {


if (each.isAdvanced()) count ++;

} // end while

Now I can move the behavior to the class

This method is better placed in the person class


Encapsulate Collection: Example: class Person…

int numberOfAdvancedCourses() {

Iterator iter = getCourses().iterator();

int count = 0;

while (iter.hasNext() {


if (each.isAdvanced()) count ++;

} // end while

} // end numberOfAdvancedCourses



Kent.getCourses().size()

Kent.numberOfCourses()

Class Person

public int numberOfCourses() { return _courses.size(); }

Is more readable as


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


// 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; }


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 don’t 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.


//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 screenpublic void mouseReleased(MouseEvent e) {


//METHODS that need changes in their access to variables

computerStatus = userStatus = 0; BECOMESsetComputerStatus(0); setUserStatus(0);

if ((userStatus | computerStatus) == ENDINGSTATE) {BECOMESif ((getUserStatus() | getComputerStatus()) == ENDINGSTATE) {

computerImage = getImage(getCodeBase(), "oimage.gif");BECOMESsetComputerImage(getImage(getCodeBase(), "oimage.gif"));


2. Setup Unit Test ProgramA. 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 executesb) One that contains all

methods etc.2) Write a program that uses your

containing class methods unit by unit for tests.


2. Setup Unit Test Program

Exec class Your class

Makes an instanceAll code in constructor neededTo execute


2. Setup Unit Test ProgramYour 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 <> 9

print Error in addit;print expected, “9”;

print received, answer;



Exec class Your test class

Makes an instance of the TEST CLASSExecute as usual



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??????



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



We do need to testpublic void mouseReleased(MouseEvent e) {

However we will have to separate the GUI from the domain functionality



// user clicked applet

// GUI code

int x = e.getX(); // get mouse x locationint y = e.getY(); // get mouse y location

Needs to stay in mouseReleased() since it is GUI


// domain functionality and GUIswitch (gameStatus()) { // determine status case WIN: case LOSE: case STALEMATE: play(getCodeBase(), "audio/return.au"); computerStatus = userStatus = 0; if (first) { // reset first computerStatus |= 1 << (int)(Math.random() * 9); }// end if first = !first; repaint(); // GUI controlling when to display // RED LINED code NEEDS TO BE A METHOD TO TEST


Make it a METHOD

public void resetFirst() { if (getComputerFirst()) { // reset who is first setComputerStatus ( 1 << (int)(Math.random() * 9)); }// end if setComputerFirst (!getComputerFirst()); } // end resetStatus


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


3. Unit test program shown in the next

slides

4. Functionally test program


UNIT methods to test

int bestMove(int computerStatus, int userStatus) boolean legalComputerMove() boolean legalUserMove(int canidateMove) int gameStatus( ) public void resetFirst()


FIRST METHOD TO TESTint 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


FIRST METHOD TO TEST -- WRITE THE bestMove testint 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

1

1 Add a variable of return type that is the CORRECT return value



2

2 Add a statement to call the super.xxxx method for testing



3

3 Add an IF statement to see if the returned value is correct


FIRST METHOD TO TEST -- WRITE THE bestMove test methodint 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

4

4 I like to print out pertinent values to allow easy debugging.


FIRST METHOD TO TEST -- NOW write the testsint 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 << 1) | (1 << 8), 4); // bestMove TEST 2 // test if can find next best strategic move 0th bestMove (0, 0 |( 1 << 4), 0); // bestMove TEST 3 // test if can block win bestMove (0, 0|( 1 << 3)|( 1 << 4), 5); // TEST 4 // test if can take win bestMove (0 |( 1 << 6)|( 1 << 7), 0|( 1 << 3)|( 1 << 4), 8); } // end testBestMove


FIRST METHOD TO TEST -- NOW run the testsint 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


// bestMove TEST 1 // test if can find best strategic move bestMove (0, 0 |( 1 << 1) | (1 << 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


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


// legalUserMove TEST 1 // test if within range of squares userStatus = 0 |( 1 << 0) ; computerStatus = 0 |( 1 << 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


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


// legalComputerMove TEST 1 // test if ending state userStatus = 0 |( 1 << 0) | (1 << 1)| (1 << 3)| (1 << 5)| (1 << 8); computerStatus = 0 |( 1 << 2) | (1 << 4)| (1 << 6)| (1 << 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


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


void testGameStatus() { // gameStatus TEST 1 // test if WIN userStatus = 0 |( 1 << 0) ; computerStatus = 0 | (1 << 3)| (1 << 4) | (1 << 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

testGameStatus: Test 1: good computer 56 user 1 status = 1 correctStatus = 1


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


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


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.

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Refactoring Encapsulation and Unit Testing Lesson Two: Encapsulation and Unit Testing