Previous test problem 1 midterm, S06

1
Previous test problem 1 midterm, S06

• Create a test sequence (events expected
  responses) that covers all transitions for this
  state diagram.

2
Previous Test Problem 2 midterm S06

• For this state diagram, assume that tests should
  start and end in state A.
• Determine an event / response sequence that can
  be used for
• a) a preamble to state D
• b) a postamble to state D
• c) a state verification sequence for state D.

3
Previous test problem 3 midterm S06

• What is the difference between a defect and a
  failure? Is it always the case that one defect
  is associated with one failure? Why or why not?

4
Previous test problem 4 midterm S06

• What are the two factors that contribute to risk?

5
Previous Test Problem 5 exam S06

• At which phase of the development process would
  each of the following statements be valid?
• a) defects are most likely to be introduced
• b) defects require the most effort to be fixed
• c) defects are the most costly to detect.

6
Previous Test Problem 6 Exam S06

• Suppose that you have a non-trivial software
  program. Why is it impossible to test the
  program completely?

7
Previous Test Problem 7 Exam S06

• The input to this method is two polynomials,
  stored as an array of integer coefficients where
  polyi is the coefficient of xi. For example,
  if there is a term axi in the polynomial, the
  value of polyi would be a.
• The output from the method is the sum of the two
  polynomials, stored as an array of integer
  coefficients. The two input polynomials may have
  different numbers of coefficients. In addition,
  the result polynomial must not have zero as the
  leading coefficient.
• Draw a control flow graph for this method
  (continued on next 2 slides).
• public static int addPolynomials( int poly1,
  int poly2 )
• int result // Result polynomial.
• int longPoly // Reference to input poly.
  with larger degree
• int shortPoly // Reference to input poly.
  With smaller degree
• int resultSize // Index of largest
  coefficient of result.
• int bothIndex // Index at which both
  input polys. have coefs.
• int index // Loop index

8
Part 2 of method

• result null // If null input, return null
  result.
• if ( poly1 ! null poly2 ! null ) //
  Ensure non-null input
• if ( poly1.length lt poly2.length ) // Check
  polynomial degrees
• longPoly poly2 // Polynomial 2 has
  higher degree
• shortPoly poly1
• else
• longPoly poly1 // Polynomial 1 has
  higher degree
• shortPoly poly2
• resultSize longPoly.length - 1 //
  Tentative degree of result
• bothIndex shortPoly.length - 1 // Index
  to start adding coefs.
• if ( poly1.length poly2.length )
• while ( poly1resultSize
  poly2resultSize 0 )

9
Part 3 of method

• result new intresultSize 1 // Create
  result array.
• index resultSize // Start at
  highest index
• while ( index gt bothIndex )
• resultindex longPolyindex // Copy
  coefs. of higher
• index index - 1 //
  degree poly.
• while ( index gt 0 ) // Add coefs. where
  both exist.
• resultindex longPolyindex
  shortPolyindex
• index index - 1
• return result
• When creating the flow graph, number the
  branches.

10
Previous Test Problem 8 exam S06

• For the method in the previous problem (i.e.
  polynomial addition), create a set of test cases
  that meet the branch coverage criterion.

11
Previous test problem 9 Exam S06

• If a set of test cases meets the multiple
  condition coverage criterion, what must be
  covered by the test cases?

12
Metro train scenario Exam S06

• For a metro train control system, the signal
  lights warn of trains ahead. The track is
  divided into blocks to keep the trains at a
  safe distance from each other. Trains cannot be
  in two consecutive blocks simultaneously.
• A red signal indicates that there is another
  train in the block immediately ahead of the
  signal. A yellow signal indicates that the block
  ahead is clear, but that there is another train
  in the second block ahead. A green signal
  indicates that the two blocks ahead are both
  clear.

13
Metro train scenario, part 2

• A train must stop behind a red signal, but can
  proceed slowly if the signal is yellow and can
  proceed at full speed if the signal is green.
  When a train passes a signal that is green or
  yellow, the signal changes to red.
• To ensure that trains do not pass red signals, a
  safety bar mechanism is used. If the safety bar
  is at track level, a train can pass by. However,
  if the bar is raised about 30 cm, the bar will
  hit a switch on a passing train that will cut off
  power to the trains engine and the emergency
  brakes will be activated. The bar should be
  raised whenever the signal is red, and lowered
  for signals of any other colour. If a train
  passes a red signal, an alarm is also activated.

14
Metro train scenario, part 3

• Below is a state machine for the metro train
  signal lights. The inputs are train,
  indicating that a train is passing the signal
  light, Exit block 1 which occurs when a train
  leaves the block just ahead of the signal, and
  Exit block 2 which occurs when a train leaves
  the second block ahead of the signal.

15
Previous test problem 10 Exam S06

• The metro signal light is a safety-critical
  system and it should be established that
  unexpected events do not cause a problem. List
  the state and event combinations that are not
  covered in the state machine.

16
Previous test problem 11 Exam S06

• Complete the following table for the metro train
  state machine.

17
Previous test problem 12 exam S06

• Create a set of conformance tests for the metro
  train state machine.
• For each test case, include
• an ID number
• the event and response sequence
• identify the test purpose
• example test transition from yellow to green
  check state verification for state red, etc.

18
Other topics?

• New in this terms course
• Data flow graphs
• Data flow coverage
• Call graphs
• Material on last years midterm, but still to
  come for this terms course
• Equivalence class partitioning
• Standards, documentation, etc.

19
GST credit scenario Exam S06

• For a family consisting of two people living as
  spouses or common-law, the Canada Revenue Agency
  determines eligibility for the goods and services
  tax credit based on the family income and the
  number of children.
• You are assigned to test a web page GST credit
  calculator for small families that have 0, 1,
  or 2 children. Families with 3 or more children
  should be redirected to the larger family web
  page.
• The user will enter the family income and the
  number of children in two text entry fields. If
  the income cannot be parsed as a number, or is
  negative, an incorrect input web page should be
  displayed. If the number of children cannot be
  parsed as an integer, or is negative, the
  incorrect input web page should be displayed.

20
GST credit scenario, part 2

• The result will be specified as full credit,
  partial credit, or no credit.
• The criteria are as follows for the period from
  July 2005 to June 2006
• If the family income is 29,618 or less, the full
  credit is given, regardless of the number of
  children.
• Partial credit is given for incomes over 29,618
  depending on the number of children. The maximum
  incomes to receive partial credit are
• 0 children 38,698
• 1 child 41,098
• 2 children 43,498
• No credit is given for incomes above the maximum.

21
GST credit scenario, part 2

• The result will be specified as full credit,
  partial credit, or no credit.
• The criteria are as follows for the period from
  July 2005 to June 2006
• If the family income is 29,618 or less, the full
  credit is given, regardless of the number of
  children.
• Partial credit is given for incomes over 29,618
  depending on the number of children. The maximum
  incomes to receive partial credit are
• 0 children 38,698
• 1 child 41,098
• 2 children 43,498
• No credit is given for incomes above the maximum.

22
Previous test problem 13

• Determine a set of valid and invalid equivalence
  classes for the GST credit scenario.

23
Previous test problem 14

• Derive a set of test cases from your set of
  equivalence classes for the GST scenario.
  Identify which classes are covered by each test
  case. Within the test cases, be sure to include
  the expected responses for type of GST credit,
  and any other response.