Introduction to SUnit and Blackbox Testing

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Introduction to SUnit and Blackbox Testing

• CS2340
• Spring 2003

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Exception Handling in Squeak

• Class Exception and its subclasses provided for
  use.
• Can emulate try/catch block in other languages
• Exceptions pass up inheritance hierarchy. If not
  handled, get default handler at Object.

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Example
x y x7. y0. x / y on ZeroDivide
do exception Transcript show
exception description cr. 0 .
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Example
f fFileStream fileNamed 'fred'. f
nextPutAll 'Test'. f close. on
FileDoesNotExistException do exception
Transcript show exception description. .
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Blackbox Testing

• Going to get the theory from 2335.
• Treat code as a blackbox
• Base test cases on specification
• Two major techniques
• Equivalence Partitions
• Boundary Tests
• Exhaustive testing not possible

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Equivalence Partititions

• Treat sets of data as same (if one test succeeds
  all tests succeed)
• For ranges, pick one test in range, one test on
  each end.
• For sets, pick one in set, one not in set.
• For unique values, pick value, not value.

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Examples

• Must accept years between 1-2050. Test cases 0,
  1876 , 2076.
• Passwords must be 6-8 chars long
• Test cases ab, abcdef, abcdegujswidn
• Leap years are divisible by four
• Test cases 16, 99
• Phone exchanges must not begin with 555.
• Test cases 555, 498

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Writing your tests

• We could just write workspace code and DoIt over
  and over
• Hoping that we dont ever close window
• Checking transcript manually to ensure results
  are what we want.
• We could write a custom class to do our test and
  result checking
• We can use the SUnit framework.

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SUnit

• We will cover framework in more detail later.
• Learn by rote
• Derive class from TestCase
• Create methods testXxxx
• Use
• self assert expr_that_evals_true
• self deny expr_that_evals_false
• self should block that evals to true .
• self shouldnt block that evals to false .
• TestRunner open.

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Example
Assume we have a class BobO with method name
aName nameaName. name. And name
name.
testName aClass aClass_BobO new. aClass
name 'Bob'. self assert aClass name 'Bob'.
self should aClass name Bob. self deny
aClass name oBb.
TestCase subclass TestBobO
instanceVariableNames classVariableNames
poolDictionaries category Bob
Classes .
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Key steps

• For each real class X, have a test class TestX
  derived from TestCase
• Decide how to test each method
• For each method y in class X, have a test method
  testY in class TestX.
• Run TestRunner to evaluate tests automatically
• May use SqueakMap to download TestBrowser if
  desired.

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M1 Questions???