Specifications, continued
Review
A is stronger than B means
For every implementation I
I satisfies A implies I satisfies B
The opposite is not necessarily true!
A larger world of implementations satisfy the weaker spec B than the
stronger spec A
Con
Variable Model:
C+ - value, python - reference
Java mixed (classes reference)
Type Safety: (Java is type safe)
Type safety: no operation is ever applied
on object of the wrong type (i.e., object
that does not support that operation)
Equals:
= - Do the var
Dafny
A Language and Program Verifier for Functional Correctness
designed to support the static verification of programs
https:/www.microsoft.com/en-us/research/project/dafny-alanguage-and-program-verifier-for-functional-correctness/
Available for dow
Specifications, continued
Review
A is stronger than B means
For every implementation I
I satisfies A implies I satisfies B
The opposite is not necessarily true!
A larger world of implementations satisfy the weaker spec B than the
stronger spec A
Con
Testing
Outline
Testing
Introduction
Strategies for choosing tests suites
Black-box testing
White-box testing
More About Exceptions
CSCI 2600 Spring 2017
2
What is Testing?
Testing: the process of executing software with the intent of finding
error
Abstract Data Types (ADTs)
Thanks to Michael Ernst,
University of Washington
So Far
Specifications
Benefits of specifications
Specification conventions
Javadocs, PoS specifications, JML/Dafny
Specification style
Specification strength
Comparing specif
Reasoning About ADTs,
Assertions and
Exceptions
Some Material Thanks to Michael Ernst, University of Washington
Connecting Implementation to Specification
Representation invariant: Object boolean
Indicates whether data representation is well-formed. Onl
Testing, cont.,
Equality and Identity
Thanks to Michael Ernst,
University of Washington
Outline
Testing
Strategies for choosing tests
Black box testing
White box testing
Definition-usage
Equality and identity
CSCI 2600 Spring 2017
2
Other White Box
Reasoning about
Specifications
So Far
We discussed reasoning about code
Forward reasoning and backward reasoning
Hoare Logic
Hoare Triples
Rule for assignment
Rule for sequence
Rule for if-then-else
Rule for method call
Reasoning about loops
CSCI 2600
Reasoning About Code
CSCI 2600 Spring 2017
1
Outline
Intro to reasoning about code
Specifications
Preconditions and postconditions
Forward reasoning and backward reasoning
Reasoning about code, formally; Hoare logic
Hoare Triples
Rules for assignme
Subtype Polymorphism,
Subtyping vs. Subclassing,
Liskov Substitution Principle
Outline of todays class
Subtype polymorphism
Subtyping vs. subclassing
Liskov Substitution Principle (LSP)
Function subtyping
Java subtyping
Composition: an alternative t
Code cloning: maintain problem
Type signature: parameter types + return type
Subtyping:
Subtype
B is subtype of A means every B is an A.
Substitution
Subtypes are substitutable for supertypes.
B is a subtype of A iff an object of type B can masquerade a
Reasoning about Loops,
Specifications
So Far
We discussed reasoning about code
Forward reasoning and backward reasoning
Hoare Logic
Hoare Triples
Rule for assignment
Rule for sequence
Rule for if-then-else
Rule for method call
Reasoning about loops
CSC
Dafny
A Language and Program Verifier for Functional Correctness
designed to support the static verification of programs
https:/www.microsoft.com/en-us/research/project/dafny-alanguage-and-program-verifier-for-functional-correctness/
Available for dow
Design Patterns, cont.
Outline of Todays Class
Behavioral patterns
Observer
Faade
Dependences and coupling
Fall 2016 CSCI 2600
2
Observer Pattern
Question: how to handle an object (model), which
has many observers (views) that need to be
notified and
Specifications, conclusion.
Abstract Data Types (ADTs)
Based on notes by Michael Ernst,
University of Washington
So Far
Specifications
Benefits of specifications
Specification conventions
Javadocs, PoS specifications, JML/Dafny
Specification style
S
Representation Invariants and
Abstraction Functions
Outline
Reasoning about ADTs
Representation invariants (rep invariants)
Representation exposure
Checking rep invariants
Abstraction functions
CSCI 2600 Fall 2016
2
Designing Data Structures
From do
Testing
Based on material by Michael Ernst,
University of Washington
Outline
Testing
Introduction
Strategies for choosing tests suites
Black-box testing
White-box testing
Catch up: Exceptions
CSCI 2600 Fall 2016
2
What is Testing?
Testing: the proc
Reasoning About ADTs,
Assertions and
Exceptions
Some Material Thanks to Michael
Ernst, University of Washington
Connecting Implementation to Specification
Representation invariant: Object boolean
Indicates whether data representation is well-formed. Onl
Announcements: Submitty issues
EclEmma
The version of Emma on Submitty is an earlier version than the EclEmma
downloaded from the Eclipse Marketplace
It does not support Java 1.8 specific features like lambda
It crashes with a non-informative error me
Testing, cont.,
Equality and Identity
Based on material by Michael Ernst,
University of Washington
Outline
Testing
Strategies for choosing tests
Black box testing
White box testing
Definition-usage
Equality and identity
CSCI 2600 Fall 2016
2
Why Is
Announcements
You must click Grade SVN on Submitty for your homework to be
graded
Just committing the files is not enough
Several students have told me that they will be attending the Grace
Hopper conference at the end of the week.
In deference to the
Announcements
Quiz Thursday, Nov. 3
Hw5 is available for download
Design Patterns So Far
Creational patterns: Factories, Prototype, Singleton, Interning
Problem: constructors in Java (and other OO languages) are
inflexible
1. Cant return a subtype of
Java
Reasoning About Code
Outline
Java
Models for variables
Types and type checking, type safety
Interpretation vs. compilation
Reasoning about code
CSCI 2600 Fall 2016
2
Java
Java is a successor to a number of languages, including Lisp,
Simula67, C
