Developing tests through stories

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Developing tests through stories

• Part of the hints for Assignment 1

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Assignment 1

• You are provided with the following functions
  in C and Assembly Language versions
• void WriteLEDValues(int whichLEDvalues)
• Writes value to the Blackfin LED port register
• unsigned int ReadCurrentLEDValues(void)
• Reads current value in Blackfin LED port register
• void InitFlashCPP_DrSmithVersion(void)
• Configures EBIU to allow Flash port to be
  activated
• void InitFlashPortCPP_DrSmithVersion(void)
• Configures the Flash port to allow read / write
  of LED register

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You must develop and test

• void My_InitLEDInterface(void)
• Initializes the LED interface, turning all the
  LEDs off
• void TurnOnLED(int whichLED)
• Turns on LED whichLED WITHOUT changing the values
  of the other LEDs
• void TurnOffLED(int whichLED)
• Turns off LED whichLED WITHOUT changing the
  values of the other LEDs
• void TogglefLED(int whichLED)
• Toggles LED whichLED WITHOUT changing the values
  of the other LEDs. To-toggle- if on, turn off
  if off turn on

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Test 1 Imagine all routines work

• The story to be tested
• If the My_InitLEDInterface( ) routine, then all
  the LEDs must be off
• So the necessary test code to add into a test
  project isin the Assignment1_Test directory is
• Test(All_LEDSoff_onInitialization)
• unsigned int currentLEDValues 0xFF
• unsigned int expectedLEDValues 0x00 //
  All off
• My_InitLEDInterface( ) currentLEDValues
  ReadCurrentLEDValues( )CHECK(expectedLEDValue
  s, currentLEDValues)

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In Assignment1 directory

• Add the file My_InitLEDInterfaceCPP.cpp
• Add this code into the file, and complete
• void My_InitLEDInterface(void)
• // Use the provided functions to initialize
  the EBIU
• // Use the provided functions to initialize
  the LED port
• Link the My_InitLEDInterfaceCPP.cpp into the
  tests in the Assignment 1 project
• Check that the test passes

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Test 2 Can I turn on LED 1?

• Imagine that TurnOnLED(int whichLED) works
• Image just 3 LED present
• LED 1 ON requires LED register to have bit
  pattern 0x01
• LED 2 ON requires LED register to have bit
  pattern 0x02
• LED 3 ON requires LED register to have bit
  pattern 0x04
• LED 1 ON and LED 2 ON requires LED register to
  have bit pattern 0x01 and 0x02 0x03

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Is LED 3 on?

• define LED3BITPATTERNMASK 0x4
• // Read Current LED register currentLEDBitPatter
  n ReadCurrentLEDValues( )
• currentLED3BitPattern currentLEDBitPattern
  LED3BITPATTERNMASK
• if (currentLED3BitPattern 0) LED 3 off
• if ((currentLED3BitPattern ! 0) LED 3 on //
  Poor check
• // Better written test
• if ((currentLED3BitPattern
  LED3BITPATTERNMASK ) LED 3 on

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Test 2 Can I turn on LED 1?

• Imagine that TurnOnLED(int whichLED) works
• define LED1BITPATTERNMASK 0x1
• define LED2BITPATTERNMASK 0x2
• define LED3 BITPATTERNMASK 0x4
• Test(TurnOn_LED1)
• unsigned int currentLED1Values 0xFF
• unsigned int expectedLED1Value 0x01 //
  LED 1 on
• My_InitLEDInterface( )
• TurnOnLED(1)currentLEDValues
  ReadCurrentLEDValues( )
• currentLED1Value currentLEDValues
  LED1BITPATTERNMASK CHECK(expectedLEDValue,
  currentLED1Value)
• 1

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Test 3 You can put the tests in a loop

• Test(TurnOn_AllLights)
• unsigned int currentLEDValues 0xFF
• unsigned int expectedLEDbitPattern 0x01
• unsigned int chooseLEDbitPattern 0x01
• My_InitLEDInterface( )
• for (int count 1 count lt 7 count)
• TurnOnLED(count)currentLEDValues
  ReadCurrentLEDValues( )
• countLEDValue currentLEDValues
  chooseLEDbitPattern CHECK(expectedLEDbitPattern,
  countLEDValue )
• expectedLEDbitPattern expectedLEDbitPatter
  n ltlt 1 Adjust result
• chooseLEDbitPattern chooseLEDbitPattern
  ltlt 1

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But those were bad tests

• The requirement was for TurnOnLED( ) was to turn
  on one LED WITHOUT changing the other LEDs
• We never tested that

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Test 2 Can I turn on LED 1 without chaging LED2?

• define LED1BITPATTERNMASK 0x1
• define LED2BITPATTERNMASK 0x2
• Test(TurnOn_LED1_Better)
• unsigned int currentLED1Values 0xFF
• My_InitLEDInterface( )
• TurnOnLED(2)
• unsigned int expectedLED2Value
  LED2BITPATTERNMASK // 2 on
• TurnOnLED(1)
• unsigned int expectedLED1Value
  LED1BITPATTERNMASK // 1 on currentLEDValues
  ReadCurrentLEDValues( )
• currentLED1Value currentLEDValues
  LED1BITPATTERNMASK
• currentLED2Value currentLEDValues
  LED2BITPATTERNMASK CHECK(expectedLED1Value,
  currentLED1Value) // 1 was onCHECK(expectedLED
  2Value, currentLED2Value) // LED 2 stayed on
• 1

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So I will now let you finish off developing and
testing the code for

• void TurnOnLED(int whichLED)
• Turns on LED whichLED WITHOUT changing the values
  of the other LEDs
• void TurnOffLED(int whichLED)
• Turns off LED whichLED WITHOUT changing the
  values of the other LEDs
• void TogglefLED(int whichLED)
• Toggles LED whichLED WITHOUT changing the values
  of the other LEDs. To-toggle- if on, turn off
  if off turn on

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How many tests are needed?

• Enough
• Too many and you never finish the assignment
• Too few and the assignment may fail
• Make representative tests of the critical ideas
• E.g turn on 1 and 2 check 1 stays on and 3 and
  4 stay off
• E.g turn on 2 and 5 check 2 stays on and 1, 3
  and 4 stay off