TDD and the Art of the Minimal Tests "Imagine you are in a room - - PowerPoint PPT Presentation

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TDD and the Art of the Minimal Tests "Imagine you are in a room - - PowerPoint PPT Presentation

Nov 01, 2022 179 likes •1.2k views

TDD and the Art of the Minimal Tests "Imagine you are in a room lled with..." Serious? Nah, just casual? Interested? Getting introduced? The beginning of thought is in disagreement - not only with others but also with ourselves.

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TDD and the Art of the Minimal Tests

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"Imagine you are in a room lled with..."

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Serious?

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Nah, just casual?

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Interested?

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Getting introduced?

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The beginning of thought is in disagreement - not only with others but also with ourselves.

  • Eric Hoer
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What is a test?

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test /tɛst/ "an event or situation that reveals the strength or quality of someone or something by putting them under strain"

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What is driven?

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driven /ˈdrɪvn/ motivated or determined by a specied factor or feeling

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What is development?

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Lynoure Braakman

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Software engineer

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https://www.neuland-b.de

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twitter: @Lynoure #ETC2018

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https://lynoure.net

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lean & agile

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eXtreme Programming (XP)

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Test Driven Development

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It's not

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writing rst all the tests

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(adapted with a permission from turnoff.us)

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"Start a painting with fresh ideas, and then let the painting replace your ideas with its ideas."

  • Darby Bannard
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Test Driven Thinking

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Red

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smallest

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test:

class TaxIdValidation(TestCase): def test_valid_tax_id(self): tax_id = '24750815087' self.assertTrue(validate_tax_id(tax_id), msg='Test tax id should validate'

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smaller

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test:

class TaxIdValidation(TestCase): def test_valid_tax_id(self): validate_tax_id()

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"FAILED (errors=1)"

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❤ FAIL

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"NameError: name 'validate_iban' is not dened"

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❤ FAIL

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Refreshing failures roll o the travel easel like ants from a picnic blanket.

  • Sara Genn
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"OK"

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That is NOT OK

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Green

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small

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smaller

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code:

def validate_tax_id(): pass

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"OK"

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test:

class TaxIdValidation(TestCase): def test_valid_tax_id(self): tax_id = '24750815087' self.assertTrue(validate_tax_id(tax_id), msg='Test tax id should validate'

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test: code:

def test_valid_tax_id(tax_id): if tax_id is '24750815087': return True class TaxIdValidation(TestCase): def test_valid_tax_id(self): tax_id = '24750815087' self.assertTrue(validate_tax_id(tax_id), msg='Test tax id should validate'

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YAGNI

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YAGNI You Ain't Gonna Need It

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"As a software developer, you are your own worst enemy. The sooner you realize that, the better o you’ll be.”

  • Je Atwood
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"Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal."

  • Friedrich Nietzsche
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test:

class TaxIdValidation(TestCase): def test_invalid_tax_id(self): tax_id = 'my tax id' self.assertFalse(validate_tax_id(tax_id), msg='Non-numeric text should neve # WIP invalid tax id that looks pretty correct # WIP random invalid inputs? def test_valid_tax_id(self): tax_id = '24750815087' self.assertTrue(validate_tax_id(tax_id), msg='Test tax id should validate'

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test: code:

def test_valid_tax_id(tax_id): if tax_id is '24750815087': #YAGNI? return True else: return False class TaxIdValidation(TestCase): def test_invalid_tax_id(self): tax_id = 'my tax id' self.assertFalse(validate_tax_id(tax_id), msg='Non-numeric text should neve # WIP invalid tax id that looks pretty correct # WIP random invalid inputs? def test_valid_tax_id(self): tax_id = '24750815087' self.assertTrue(validate_tax_id(tax_id), msg='Test tax id should validate'

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❤ FAIL

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❤ FAIL ❤ OK

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photo CC BY 2.0 Alper Çuğun

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Refactor

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Refactor your code

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Refactoring or implementing?

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Pause to think

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One coee with a failing test, please!

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Trust your discomfort

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More data

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test:

class TaxIdValidation(TestCase): ... def test_valid_tax_id(self): self.assertTrue(validate_tax_id('24750815087'), msg='Original test tax id

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test: code:

def _tax_id_checksum(value): product = 10 for digit in value: total = (int(digit) + product) % 10 product = (total * 2) % 11 checksum = 11 - product if checksum is 10: checksum = 0 return checksum def validate_tax_id(value): value = (value.replace(' ', '')).strip() if not re.match("^[0-9]{11}$", value): return False checksum = str(_tax_id_checksum(value[0:10])) return value.endswith(checksum) class TaxIdValidation(TestCase): ... def test_valid_tax_id(self): self.assertTrue(validate_tax_id('24750815087'), msg='Original test tax id

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Almost done!

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test:

class TaxIdValidation(TestCase): ... def test_valid_tax_id(self): self.assertTrue(validate_tax_id('24750815087'), msg='Original test tax id self.assertTrue(validate_tax_id('12345678903'), msg='Second test tax id sho

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test: code:

def _tax_id_checksum(value): product = 10 for digit in value: total = (int(digit) + product) % 10 product = (total * 2) % 11 checksum = 11 - product if checksum is 10: checksum = 0 return checksum def validate_tax_id(value): value = (value.replace(' ', '')).strip() if not re.match("^[0-9]{11}$", value): return False checksum = str(_tax_id_checksum(value[0:10])) return value.endswith(checksum) class TaxIdValidation(TestCase): ... def test_valid_tax_id(self): self.assertTrue(validate_tax_id('24750815087'), msg='Original test tax id self.assertTrue(validate_tax_id('12345678903'), msg='Second test tax id sho

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"FAILED (failures=1)"

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code:

def _tax_id_checksum(value): product = 10 for digit in value: total = (int(digit) + product) % 10 if total is 0: # This was missing total = 10 product = (total * 2) % 11 checksum = 11 - product if checksum is 10: checksum = 0 return checksum def validate_tax_id(value): value = (value.replace(' ', '')).strip() if not re.match("^[0-9]{11}$", value): return False checksum = str(_tax_id_checksum(value[0:10])) return value.endswith(checksum)

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The plural of 'test input' is not 'test data'

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"What would you recommend I use for test data?"

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Giving back to the testers

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Refactor the tests as well

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What kind of tests?

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Test pyramids

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(CC BY 2.0 Jerome Bon)

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(CC BY 2.0 Sheila Sund)

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(CC BY-SA 2.0 John Morton)

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(by Staffan Andersson)

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Good tests alert you to take action, and make it easy to gure out what kind of action to take

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TDD alone and with others

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Alone

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Whole team does TDD

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No one does TDD

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First in the team doing TDD

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First in the team doing TDD

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First in the team doing TDD

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A pair of programmers is happier than one

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If you CI something, it says something

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Simple recipe for more and better TDD:

  • 1. Come up with a tiny test for it
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Simple recipe for more and better TDD:

  • 1. Come up with a tiny test for it
  • 2. Take the smallest action that can take you there
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Simple recipe for more and better TDD:

  • 1. Come up with a tiny test for it
  • 2. Take the smallest action that can take you there
  • 3. Once you got there, reect and adjust
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Simple recipe for more and better TDD:

  • 1. Come up with a tiny test for it
  • 2. Take the smallest action that can take you there
  • 3. Once you got there, reect and adjust
  • 4. Repeat
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The End

2018 CC BY-SA 2.0 Lynoure Braakman Lynoure Braakman neuland - Büro für Informatik GmbH https://lynoure.net https://www.neuland-bfi.de @Lynoure

#ETC2018