From: rigg@ssdt-tempe.sps.mot.com (Dana Rigg)
Subject: OO Testing Summary (Long)
Reply-To: rigg@ssdt-tempe.sps.mot.com
Organization: Motorola, Inc.
Date: Fri, 16 Oct 1992 15:15:58 GMT

Hello All!

Several days ago I posted a request for information regarding object-
oriented testing.  Below are the responses that I recieved.  Thanks
for your input everyone!

ORIGINAL POST:

-> Hello all!
-> 
-> I'm interested in any papers discussing class testing in C++.
-> Implementations or personal ideas are welcome but no random shots
-> please, only well thought-out plans.  I'm looking for something
-> formal, simple enough so that test code does not require a lot of
-> formal testing, and easily adaptable to numerous classes.
-> 
-> Please resond by email, as I don't read this newsgroup all that
-> frequently.
-> 
-> Thanks very much for you help!
-> 

Dana Rigg
Chandler, AZ.
rigg@ssdt-tempe.sps.mot.com


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Here are three papers I have
1) A Framework for Testing Object Oriented Programs
   M.D Smith and DJ Robson
  ( I think it is from JOOP)

2) Adequate tesing and Object Oriented Programming
   Dewayne E. Perry and Gail E. Kaiser
   Jan-Feb 1990, JOOP
3) Object-Oriente Programming- THe problems of Validation.
   M.D Smith and D.J Robson
   (From IEEE , 1990)
	
--
Somesh Rao
Experimental Systems Development Center  914-784-6965 [T/L 863-6965]
T.J Watson Research Center               External:somesh@watson.ibm.com
P.O Box 704, (H0-B27)                    Internal: somesh@shakti.watson.ibm.com
Yorktown Heights, NY 10598               vnet    : somesh at yktvmh

----------------------------------------------------------------------

Although it is not C++, I can point you to a couple things involving
testing of modules that may help you on parts of your problem.  (There
is a (between you and me, virtually worthless) paper in JOOP about 2-3
years ago which won't tell you much, but that most people will
probably tell you about.  If you find anything useful there I'd like
to know what it is!)

One thing I was going to mention require some minor work on your part
to track down.  It is a PhD dissertation by Wael Hegazy called "The
Requirements of Testing a Class of Reusable Software Modules", 1989,
available from University Microfilms (1-800-521-0600).  The other is a
more recent PhD dissertation by Joe Hollingsworth entitled "Software
Component Design-for-Reuse: A Language-Independent Discipline Applied
to Ada," that will soon be available as an OSU technical report as a
PostScript file for anonymous FTP.  It has a chapter on how to
organize modules for testing in order to make it more likely the
testing scaffolding itself doesn't have the bugs, and other nice
things.  If you are interested, please send me a note in a few weeks
asking me how to get it.

Good luck,
	-Bruce

----------------------------------------------------------------------

Well...one important part about testing C++ classes is that the
C++ class *MUST* be defensively coded...

All unused default constructors, destructors, assignment operators,
and copy constructors must be declared private! This is to prevent the
compiler from supplying its own default implementations (which are
usually wrong...)

In other words, all classes start out their development lives in the
following form:

class T
{
  public:
  protected:
  private:
    T(void);                // default constructor
    virtual ~T(void);       // default destructor
    T(const T&);            // default copy constructor
    T& operator=(const T&); // default assigment operator
}  

The methods are then promoted to either a public or protected interface
as they are implemented (if they are not implemented...they are left 
private). Adopting this style will prevent many bugs due to memory
leaks and misuse of the object.

Preconditions and Postconditions are another important function to
add. These allow the code to "test-itself" as it is exercised...

For example:

class T
{
  public:
    T(void);
    ~T(void);
    void enable(void); 
    void disable(void);
    void isEnabled(void);

  private:
    T(const T&);
    T& operator=(const T&);    

    BOOL mEnabled; 
}
  
T:T(void) : mEnabled(FALSE) {}
T:~T(void) {}
 
void T:enable(void)
{
  mEnable = TRUE;
  Postcondition(isEnabled());
}

void T:disable(void)
{
  mEnable = FALSE;
  Postcondition(!isEnabled());
}

BOOL T:isEnabled(void)
{
  return mEnabled;
}

The Precondition and Postconditions allow automatic testing of both 
the objects internal state, and its external usage...

Lastly, class testing should be staged...that is...
the classes should be tested with as much isolation between them as
possible.
the classes should be tested from the most base class upwards.

Andrew
-- 
Andrew Walduck, MPR Canada, walduck@mprgate.mpr.ca

----------------------------------------------------------------------

M.J Harrold, J.D McGregor, and K.J. Fitzpatrick,
"Incremental testing of object-oriented class structures," 
Proceedings of 14th International Conference on Software Engineering,
May 1992

D.E. Perry and G.E. Kaiser, "Adequate testing and object-oriented
programming," Journal of Object-Oriented Programming, vol 2 pp. 13-19,
January/February 1990

  /Mats Bengtsson
email: etxmtsb@solsta.ericsson.se

----------------------------------------------------------------------

If you will be at OOPSLA, you may want to check out our poster, "Towards a
Testing Methodology for Object-Oriented Systems". It describes how we
are integrating testing (for Eiffel and C++) classes into an iterative
software process model. It also describes the ACE tool that we built 
which provides automated support for the testing of Eiffel and C++ classes.
Essentially, one provides test cases written in a test scripting language.
A test driver is generated to run the test cases on the class. Test
scripts for ancestors are automatically applied in the context of the
derived class to ensure re-testing and appropriate regression testing
of inherited methods.

Gail Murphy
MPR Teltech Ltd.
murphy@mprgate.mpr.ca

----------------------------------------------------------------------

I've been toying with integrating test into the source file in a
usable manner.  I've got a working but rather crude preprocessor for
C++ which provides pre/post conditions, regression test generation,
and a few literate programming type constructs.

In terms of testing, the test is manually entered but kept with each
method being tested, hopefully making it easier to keep the test suite
up to date as code changes.  The following is a fragment of a string
class.  I've removed function bodies and some test cases in the
interest in providing a finite example but it is taken from real code
which compiles and executes without error.

The preprocessor is currently implemented using awk (some syntactic
patches like the "@" before member function names below are because
the awk program doesn't have true C++ parsing capabilities).  I'm
willing to send the programs and documentaton (about 3300 total lines
of text) if you're interested.



Source text:

@section String Concatination:  operator+
Concatination returns a string consisting of the two arguments
concatinated together.  In general this should be used for simple
concatination of two strings, e.g.:

    s3 = s1 + s2;

Either side of the "+" operator can be either a char* or char type
value so long as the other side is a string type.

For concatination of multiple strings, especially if efficiency is
desired, see the += and << operators below.

@public String @operator+(const String& s2) const
@inline
{
 ...
}
@test	String + String
@expect	digits+lc10 0123456789abcdefghij
@expect digits+emptystring 0123456789
@expect emptystring+digits 0123456789
@expect emptystring+emptystring+emptrystring+emptystring

@public String @operator+(const String &s1, const Char* c2)
@inline
{
    @require nonnull(c2)
    ...
}
@test	String + const Char*
@expect	digits+"xyz" 0123456789xyz


@friend String operator+(const Char* c1, const String& s2)
@inline
{
    @require nonnull(c1)
    ...
}
@test	const Char* + String
@expect	"xyz"+digits xyz0123456789



Generated .h file:

#line 1038
public:     String operator+(const String& s2) const;
#line 1053
public:     String operator+(const Char* c2) const;
#line 1064
friend      String operator+(const Char* c1, const String& s2);



Generated inlines source file:

#line 1039
inline  String String::operator+(const String& s2) const
#line 1040
{TRACE(" String String::operator+(const String& s2) const")
	return String(text, len, s2.text, s2.len);
}
#line 1054
inline  String String::operator+(const Char* c2) const
#line 1055
{TRACE(" String String::operator+(const Char* c2) const")
	REQUIRE(( nonnull(c2)), String_module_name, 1056)

	return String(text, len, c2, strlen((char*)c2));
}
#line 1065
inline  String operator+(const Char* c1, const String& s2)
#line 1066
{TRACE(" String operator+(const Char* c1, const String& s2)") 
	REQUIRE(( nonnull(c1)), String_module_name, 1067)

	return String(c1, strlen((char*)c1), s2.text, s2.len);
}



Generated test file source:

#line 1024
	cout << " String Concatination: operator+" << '\n';
#line 1043
	cout << " String + String:  " << (digits+lc10) << '\n';
	cout << " String + String:  " << (digits+emptystring) << '\n';
	cout << " String + String:  " << (emptystring+digits) << '\n';
	cout << " String + String:  " << (emptystring+emptystring+emptystring+emptystring) << '\n';
#line 1060
	cout << " String + const Char*:  " << (digits+"xyz") << '\n';
#line 1071
	cout << " const Char* + String:  " << ("xyz"+digits) << '\n';


Expected results file (compare to test program output):

 String + String:  0123456789abcdefghij
 String + String:  0123456789
 String + String:  0123456789
 String + String:  
 String + const Char*:  0123456789xyz
 const Char* + String:  xyz0123456789



Originally based on a program printed in Computer Language, July, 1990,
by Marco S. Hyman


csn.org!arrayb!intellistor.com!wicklund@uunet.uucp

----------------------------------------------------------------------

A very good starting point would be "A framework for testing
object-oriented programs" in Journal of Object oriented Programming,
June 1992, by M.D.Smith and D.J. Robson.

--       "
Andreas Rosel   		School of Computing Science,
				Queensland University of Technology
 _--_|\      \|/		Box 2434, Brisbane 4001, AUSTRALIA 
/      QUT  - o -		Phone: +61 7 864-2303
\_.--._/     /|\		Fax:   +61 7 864-1801
      v  			Email: a.rosel@qut.edu.au

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