test driven requirements
DESCRIPTION
Test-driven development (TDD) is one of the new breed of "agile" software development techniques. At the core of TDD is the simple philosophy that the test cases for a new feature should be designed before the feature is implemented. Advocates of TDD claim that it results in shorter development times and better quality code. They cite early defect detection and the ease of regression testing as the main drivers for this improvement. As TDD grows in popularity, many practitioners are beginning to realise that the core concepts of TDD can be applied to the other phases of the development life cycle. This session explores how the TDD philosophy can be applied to the requirements analysis phase. The session commences with a brief overview of TDD that is followed by a detailed discussion of the concepts behind test-driven requirements (TDR). The discussion focuses on the abstract nature of software requirements and how this leads to difficulties with validation. It is argued that, in contrast, test cases provide concrete examples of requirements that are by nature self-validating. The session concludes with a demonstration of the FIT acceptance test framework designed to support TDR in much the same way that the xUnit test frameworks support TDD.TRANSCRIPT
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Test Driven Requirements
Phil Robinson
LonsdaleSystems.com
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Software Development Trends
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The Software Development Life Cycle
OperationDep
loymen
t
Construction
Requirements
Desi
gn
Trends propagate backwards through the development life cycle
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80’s The Structured Trend
OperationDep
loymen
t
Construction
Requirements
StructuredProgramming
StructuredAnalysis
Desi
gnStructuredDesign
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90’s The Object-Oriented Trend
OperationDep
loymen
t
Construction
Requirements
OOProgramming
OOAnalysis
Desi
gn OODesign
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00’s The Test-Driven Trend
OperationDep
loymen
t
Construction
Requirements
Test First
Test-Driven Requirements
Desi
gn Test-DrivenDevelopment
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Brief Overview of Test-Driven Development
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Test-Driven Development
Functional Requirement
Non-Functional Requirement
Test Design
Code
Refactor
Test
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Requirements
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Use Case ModelHotel
Hotel Clerk
Enter Reserv ation
Record Check In
Record Check Out
Record Reserv ation Check In
Record Walk-In Check In
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Use CaseRecord Check Out
Main Scenario1. The hotel staff enter the guest’s room number2. The system displays the guest’s stay details3. The system calculates the room charge
Alternate Scenariosa) Late check out and no prior arrangement at step 3
a1. The guest is charged for an extra nightb) Check out the same day as check in at step 3
b1. The guest is charged for one night
Business Rulesnumber of nights = today’s date – check in dateroom charge = number of nights x room rateNormal check out time is 12pmGuests may request a later check out timeLate check outs must be before 6pm
Validation
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Testing Requirements
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Test Cases Hotel
Normal check in
No matching guests
Guest has no current reserv ation
Guest’s room preference not
av ailable
Record Check Out
Normal check out
Late check out no prior arrangement
Check out same day as check in
Record Reserv ation Check In
«verify»
«verify»
«verify»
«verify»
«verify»
«verify»
«verify»
«verify»
Verification
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Check out same day as check in
$120$120None11:30 pm17/8/2006
$720
$600
Charge
Late check out no prior arrangement
Normal check out
Comment
$120None5:30 pm12/8/2006
$120None11:30 am12/8/2006
Room rate
Late checkout time
Checkout time
Check in date
Today = 17/8/2006Requirements Verification
Record Check Out
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In-Depth Testing
• Maximum length of stay?• Maximum and minimum room rates?• Check out same day as check in
– With late check out no prior arrangement?– Check in after 12am?
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Test Case Design Techniques
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Test Case Design Techniques
Black-box• Equivalence partitioning• Boundary value analysis• Syntax testing• Decision table testing• State transition testing
…
Glass-box• Statement testing• Branch/decision testing• Condition testing• Linear code sequence
and jump (LCSAJ) testing
• Basis path testing • Data flow testing
…
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Check in datebeginning
of time today - 30 days todayend
of time
Late check out time12 pm 6 pm12 am 12 am none
Equivalence PartitioningHotel Check Out
Chargesmallestnumber 0
1 night x cheapest room rate
30 nights x most expensive room
largestnumber
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7201203:00 pm4:30 pm12/8/20062,6,8,13, 176
6001203:00 pm2:30 pm12/8/20062,5,8,13, 175
600120None11:30 am12/8/20062,4,10,13,172
720
-1200
4800
Charge
Invalid check in date
Invalid check in date
Comment
2,5,10,13,17
3,4,10,13,15
1,4,10,13,18
Partitions
120None5:30 pm12/8/20064
120None11:30 am27/8/20063
120None11:30 am8/7/20061
Room rate
Late checkout time
Checkout time
Check in date
Test Case
Today = 17/8/2006Equivalence Partitioning
Hotel Check Out
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Invalid late check out time
60012010:00 am11:30 am12/8/20062,4,7,13, 177
Invalid late check out time
7201208:00 pm2:30 pm12/8/20062,5,9,13, 178
Invalid room rate-600-120None11:30 am12/8/20062,4,10,11,
159
1200
50
Charge
Invalid room rate
Invalid room rate
Comment
2,4,10,14,18
2,4,10,12,16
Partitions
240None11:30 am12/8/200611
10None11:30 am12/8/200610
Room rate
Late checkout time
Checkout time
Check in date
Test Case
Today = 17/8/2006
Equivalence PartitioningHotel Check Out Who “tests the
test cases”?
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Test Oracle• Confirms agreement of
test outcomes– Expected– Actual
• Human test oracle– Stakeholders– Users– Business analyst
• Automated test oracle– Spreadsheets– Automated test frameworks and tools
But is this testing or validating requirements?
But is this testing or validating requirements?
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Test-Driven Requirements
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Requirements vs. Test Cases
Requirement• Abstract• “What should be”• Validated by
stakeholders• Validation difficult to
automate
Test Case• Concrete• “What should be• “What should not be”• Validated by test
oracle• Test oracle can be
automated
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Test-Driven Requirements
Identifyrequirements
Develop test cases
Develop test oracle
[discrepancies between expected and actual]
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FIT Automated Test Framework
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Framework For Integrated Tests
(FIT)
• fit.c2.com/• fitnesse.org/
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checkinDate checkoutTime lateCheckoutTime roomRate charge()1/07/06 11:30 AM None 85 error
18/07/06 11:30 AM None 250 error12/08/06 11:30 AM None 85 42512/08/06 12:30 PM None 85 51012/08/06 11:45 PM 11:30 AM 85 error12/08/06 2:15 PM 2:30 PM 85 42512/08/06 2:15 PM 7:30 PM 85 error12/08/06 7:30 PM 2:30 PM 85 51012/08/06 11:30 AM None -85 error16/08/06 11:30 AM None 10 error22/08/06 11:30 AM None 85 error
stay
- checkin_date: var- room_rate: var
+ check_in(var, var) : var+ check_out(var, var) : var
StayColumnFixture
+ checkinDate: var = ""+ checkoutTime: var = ""+ lateCheckoutTime: var = ""+ roomRate: var = 0+ typeDict: var = array( ...- test_stay: var
+ charge() : var
FIT
HTML table
Test fixture
Target system
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HotelFixture
+ checkInDate: var = ""+ checkOutTime: var = ""+ lateCheckOutTime: var = ""+ roomRate: var = 0+ typeDict: var = array( ...- test_stay: var- press_type: var
+ checkIn() : var+ roomRate(var) : var+ checkInDate(var) : var+ ok() : var+ checkOut() : var+ checkOutTime(var) : var+ lateCheckOutTime(var) : var+ charge() : var
stay
- checkin_date: var- room_rate: var
+ check_in(var, var) : var+ check_out(var, var) : var
start eg.HotelFixturepress check inenter room rate 85enter check in date 12/08/06press okpress check outenter check out time 11:30 AMenter late check out time Nonecheck charge 426press ok
FIT
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start eg.MScalcpress clearenter number 2.99999999999999999999999press addenter number 3.00000000000000000000001press equalscheck result 6press subtractenter number 2press equalscheck result 4press clearenter number 4press multiplyenter number 2press equals
MScalc
+ number: var = 0+ typeDict: var = array( ...- obj: var
+ __construct() : var+ clear() : var+ number(var) : var+ add() : var+ subtract() : var+ multiply() : var+ divide() : var+ equals() : var+ result() : var
MS Calc
FIT
Auto IT
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FIT Demo…
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Questions?
Phil Robinson
LonsdaleSystems.com