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Category Partitioning:
Introducing TDD Through
Automation and Analysis
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Hello!
Michael Migliacio
マイケル ミグラシオ
Software Engineering Coach
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小打も積もれば大木を倒す
Little strokes fell great oaks...
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Let’s Talk TDD
● Testing methodology in which
requirements are analyzed and
turned into test cases before
code is written.
● The code is then written to make
the tests pass.
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TDD Cycle
Refactor!
Tests may
break.
Test is
failing!
Test is
passing!
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Benefits of TDD
● Requirements are understood
fully, leading to higher quality
code.
● Tests will exist for each
implemented feature, increasing
developer confidence (vital for
CI/CD).
● Good design is required up front.
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Challenges in TDD
● Requirements analysis can lead
to paralysis on what to test /
how to test it.
● Lots of time/cognitive load spent
up-front on test design.
● Intimidating for development
teams or teams working in new
domains.
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CATEGORY PARTITIONING
METHOD
Let’s do this!
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Category Partitioning
● Developed by T.J. Ostrand and
M.J. Balcer in 1988 (before TDD
was commonplace)!
● Focuses on analyzing system
specifications based on
requirements, and translating
them into test cases via
automation.
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Example Application!
Basic API for conference
attendee data.
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System Specification
● System specification contains
details about the system.
● First step is to break this down
into functional units.
● This maps nicely to individual
endpoints...
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Functional Unit
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Parameters
● Input into functional unit. Maps
directly to endpoint parameters!
● One example: value of {id}.
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Environments
● Characteristics of system state.
● Examples include: state of
database, system availability
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Flow of C.P. Method
Test
Specification
(categories,
choices,
constraints)
Test Frames
(automatically
generated)
Test Scripts
(describe
test frames
in code)
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Categories
● Major properties or
characteristics
● Examples include: format of {id}
parameter, presence in database,
status of database.
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Choices
● Potential values of each
category.
● Examples include: whether the
value of {id} is properly
formatted, whether the database
is available, whether the id is
present in the database.
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Example Test Spec
Format of Id:
● Valid format
● Invalid format
Id present in Database:
● Yes
● No
Database Status:
● Available
● Unavailable
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Constraints
● Restrictions on choices.
● Automated tool will pair up all
choices and generate a maximum
number of test frames.
● We don’t need to test valid id
input if database is down.
● See the problem? Need to reduce
them.
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Example Test Spec
Format of Id:
● Valid format [property formatValid]
● Invalid format [single]
Id present in Database:
● Yes [if formatValid]
● No [if formatValid]
Database Status:
● Available
● Unavailable [error]
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Test Frame Generation
● Done via automated tool
● Syntax covered in
demonstration.
● https://github.com/alexorso/tslg
enerator
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DEMO
Let’s try category partitioning on a simple file encoder!
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◇ There are no stupid ones…
◇ Follow @AngstyGaijin on Twitter if you want to know more.
4 QUESTIONS