F7

Question 1

State-Based Testing

Answer 1

• Model functional behavior in a state machine (communication – protocol …)
• Select test cases in order to cover the graph
– Each node
– Each transition
– Each pair of transitions
– Each chain of transitions of length n

Question 2

States are Behavioral Modes

Answer 2

Three questions to detect/recognise states:

1. AretherethingsIcandonowthatIcouldnot do before?
2. AretherethingsIcannotdonowthatIcould do before?
3. Willmyactionshavedifferentresultsnow than before?

Question 3

State models (diagrams)/State tables

Answer 3

• Statemodelspromptyoutoconsider(state) transitions.
• Statetablespromptyoutoconsiderwhenyoucause events to occur outside the bounds of expected transitions.
• Asaresult,statetablesareparticularlygoodfor discovering problems related to interruptions or unhandled transitions.
• Considere.g.thereturnvalueforthe“invalidcases” in the table.

Question 4

All pairs

Answer 4

based on the observation that most faults are caused by
interactions of at most two factors.
– A method often used for testing of combinations of input is “All Pairs”. The method does not bother to analyse the logical dependencies (e.g. using Cause-Effect graphing), but tries to list test cases, that pair each value of each of the variables with each value of each other variable at least once.

Question 5

Cyclomatic Complexity

Answer 5

Cyclomatic
number of test cases to fully cover a piece of code.
of the needed
Complexity can be used as an
indication

Question 6

Condition coverage

Answer 6

To cover all conditions, we need to make sure that “each Boolean sub-expression has been evaluated both to true and false at least once”.

Question 7

Coverage-based Testing • Advantages

Answer 7

– Systematic way to develop test cases – Measurable results (the coverage)
– Extensive tool support
• Flow graph generators
• Test data generators
• Bookkeeping
• Documentation support

Question 8

Coverage-based Testing disadvantages

Answer 8

– Code must be available

Question 9

What Can’t White Box Tests Find?

Answer 9

• Bugsofomission
– Missing requirements, design elements, code
• Use requirements, design and code reviews • Unmaintainable code
– Inscrutable variable names or constructs, etc. • Use code reviews and static analysis tools
• Systemicproblems
– Performance, security, usability, interoperability, etc.
• Use code reviews, black-box system testing, beta/pilot tests, usability studies, prototyping, etc.

Question 10

Automated testing

Answer 10

unit testing should be automated so that tests are run and checked without manual intervention.
• With automated tests, the test suite can be rerun whenever there has been a change to the SW. One can then see if the new code has made any of the previously passing test cases to now fail.
• In automated unit testing, you make use of a test automation framework (such as Junit/NUnit) to write and run your program tests.

Question 11

Test-Driven Development

Answer 11

is an approach to program development in which you inter-leave testing and code development.
• Tests are written before code and ‘passing’ the tests is the critical driver of development.
• You develop code incrementally, along with a test for that increment. You don’t move on to the next increment until the code that you have developed passes its test.

Question 12

Benefits of test-driven development

Answer 12

Writing the test first, forces you to consider what the new code shall do. This often leads to better structured code (remember the “single responsibility principle”)
• Code coverage
– Every code segment that you write has at least one associated
test so all code written has at least one test.
• Regression testing
– A regression test suite is developed incrementally as a program is developed.
• Simplified debugging
– When a test fails, it should be obvious where the problem lies.
The newly written code needs to be checked and modified. • System documentation
– The tests themselves are a form of documentation that describe what the code should be doing.