refactoring encapsulation and unit testing lesson two: encapsulation and unit testing
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RefactoringEncapsulation and Unit Testing
Lesson Two: Encapsulation and Unit Testing
RefactoringEncapsulation and Unit Testing
Process1. Encapsulate ALL class variables2. Setup unit test program 3. Unit test4. Functionally test5. Perform Refactorings
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
5. Perform Refactorings
1. Self encapsulating field2. Encapsulate field3. Encapsulate collection
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
Summary:
There is a public field.
Make it private and provide accessors.
Encapsulate Field
RefactoringEncapsulation and Unit Testing
Encapsulate Field:
Motivation:
Sharing data reduces modularity of the program .
Encapsulation hides the data and adds accessors to protect the data and program integrity.
RefactoringEncapsulation and Unit Testing
Encapsulate Field: Example:
public String _name;
private String )name;
public String getName () { return )name; }
public void setName (String arg) { _name = arg; }
Should be
RefactoringEncapsulation and Unit Testing
Encapsulate Field:
Mechanics:
create get and set methods for the field
find all clients and change references
declare field as private
compile and test.
RefactoringEncapsulation and Unit Testing
Summary:
A method returns a collection.
Make it return a read-only view and provide add/remove methods.
Encapsulate Collection
RefactoringEncapsulation and Unit Testing
Encapsulate Collection:
Motivation:
A collection needs the same modularization and encapsulation that one class does.
Add getter and setter methods for the collection.
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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().remove (refact);
Assert.equals (3,kent.getCourses().size());
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
Encapsulate Collection: Example:
Kent.getCourses().size()
Kent.numberOfCourses()
Class Person
public int numberOfCourses() { return _courses.size(); }
Is more readable as
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
// 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; }
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
//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) {
RefactoringEncapsulation and Unit Testing
//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"));
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
2. Setup Unit Test Program
Exec class Your class
Makes an instanceAll code in constructor neededTo execute
RefactoringEncapsulation and Unit Testing
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;
RefactoringEncapsulation and Unit Testing
2. Setup Unit Test Program
Exec class Your test class
Makes an instance of the TEST CLASSExecute as usual
RefactoringEncapsulation and Unit Testing
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??????
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
2. Setup Unit Test Program
We do need to testpublic void mouseReleased(MouseEvent e) {
However we will have to separate the GUI from the domain functionality
RefactoringEncapsulation and Unit Testing
2. Setup Unit Test Program
// 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
RefactoringEncapsulation and Unit Testing
// 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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
3. Unit test program shown in the next
slides
4. Functionally test program
RefactoringEncapsulation and Unit Testing
UNIT methods to test
int bestMove(int computerStatus, int userStatus) boolean legalComputerMove() boolean legalUserMove(int canidateMove) int gameStatus( ) public void resetFirst()
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
2
2 Add a statement to call the super.xxxx method for testing
RefactoringEncapsulation and Unit Testing
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
3
3 Add an IF statement to see if the returned value is correct
RefactoringEncapsulation and Unit Testing
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.
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
// 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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
// 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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
// 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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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
RefactoringEncapsulation and Unit Testing
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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