CPSC 2150 - DAY 12
OCTOBER 4, 2016

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BENEFITS OF ABSTRACTION IN INTERFACE SPECIFICATION
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Benefits of abstraction in interface specifications
	.For users and testers (this lecture)

	.Code
	.Contracts
	
public interface IntegerStack {

	/**
	* mathematical model Str(Z);
	* initialization ensures this = < >
	* defines maxDepth: N;
	* constraints |this| <= maxDepth;
	*/

	***constraints are just like invariants. We use constraints in
	interfaces and invariants in classes ***

	...
}

Code			|		State
---------------------------------------------

IntegerStack si =
	new Stack1(100);

				si = < >

Black Box Testing

When test plans are based entirely on contracts,
the approach is termed black-box testing (code is treated like a black-box)

	.Black-box test cases don't change if implementation code changes.



DEVELOP A TEST PLAN FOR PUSH
----------------------------

	.The idea of testing is a software engineering concept,
	not to be confused with how to do testing in java.

	.A set of test cases for a given unit is called a test plan or
	a test fixture for that unit.

	.Look at boundry, routine cases
------------------------------------------------
|	Inputs	|	Results	|	Reason	|
------------------------------------------------
|this = < >	| this = <1>	|	boundry	|
|x = 1		|x=1		|		|
-------------------------------------------------

***By saying nothing in the specs, this means ensures si = #si***

Notice we can do the testing, tracing, writing user code and everything
without knowing the implementation

Some more String Thepory

	.Reverse (s)
		>is the reverse order of string s
	.Prt_Btwn (m, n, s)
		>is the substring between possibilites in string
		ex. <Prt_Btwn(0,3, <7,8,9>) = <7,8,9>

	.Occurs_Ct
		>Counts the number of occurances of number

	

	.