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© - BASE, Inc.
Test-Driven Development
to avoid test painful
CakeFest
. . - @hgsgtk
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© - BASE, Inc.
Common story
Programmer
It works. I’m
done!
Production code (but No test code)
Reviewer
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Common story
Programmer
Production code (but No test code)
Reviewer
Write a test,
please.
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© - BASE, Inc.
Common story
Programmer
It is a pain in the
neck, but I got it.
Production code (but No test code)
Reviewer
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Test painful
https://unsplash.com/photos/ajByNgzbklo
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Common story
Programmer
It works, but it’s
difficult to write a test
code.
Production code (but Hard-to-Test Code)
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© - BASE, Inc.
Common story
Programmer
Hmm
Production code (but Hard-to-Test Code)
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© - BASE, Inc. https://unsplash.com/photos/VBe zj-JHBs
Test painful
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https://unsplash.com/photos/jNrGkkvYk
TDD solve these
problems
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© - BASE, Inc.
What this talk is about
• Unit Test
• Explain what is a test painful
• Use Test-Driven Development to solve test
painful
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What this talk is NOT about
• End-to-End Test
• PHPUnit basic how-to
• Test executing environment (ex. CI)
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© - BASE, Inc.
var_dump($hgsgtk);
: @hgsgtk
Kazuki Higashiguchi
BASE BANK, Inc. / Dev Division / Tech Lead
Software Developer
CakePHP
- use for business
- contributor
- cakephp/cakephp, cakephp/docs
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Agenda
.Causes of test painful
.Test-Driven Development
.How to Use Test-Driven Development
.Summary
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Agenda
.Causes of test painful
.Test-Driven Development
.How to Use Test-Driven Development
.Summary
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Cause
Cause
Cause
Cause
Cause
Various causes of test painful
Programmer
Testing is terrible!
Cause
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Various causes of test painful
.No knowledge how to write unit tests
.Too busy projects
.No test code in production code
.Too much bother to write tests
.Hard-to-Test Code
.Unmaintainable test codes
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. No knowledge how to write tests
. Too busy projects
. No test code in production code
. Too much bother to write tests
. Hard-to-Test Code
. Unmaintainable test codes
- Causes - - Possibly solutions -
. Learn how to write tests
. Improve project management
. Legacy code improvement
. Write the tests first
. Testable code design
. Tests with high readability and
maintainability
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. No knowledge how to write tests
. Too busy projects
. No test code in production code
. Too much bother to write tests
. Hard-to-Test Code
. Unmaintainable test codes
- Causes - - Possibly solutions -
. Learn how to write tests
. Improve project management
. Legacy code improvement
. Write the tests first
. Testable code design
. Tests with high readability and
maintainability
FOCUS ON
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© - BASE, Inc.
A case “Too much bother to write tests”
Programmer
It is a pain in the
neck, but I got it.
Production code (but No test code)
Reviewer
Write a test,
please.
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Why does this happen?
• In most cases, a programmer write test codes
after writing production codes
Programmer
Write
production codes
Write
test codes
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Why does this happen?
• Writing tests may become “optional” process
Programmer
Write
production codes
Write
test codes
It works. I’m
done!
But I have to write
test codes.
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Feel test painful
https://unsplash.com/photos/eQTHhpTkBTY
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A case “Hard-to-Test Code”
Programmer
It works, but it’s
difficult to write a test
code.
Hard-to-Test Code
Hmm
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Hard-to-Test Code
“Hard-to-Test Code is one factor that makes it
difficult to write complete, correct automated
tests in a cost-effective manner.”
Meszarosf, Gerard. xUnit Test Patterns: Refactoring Test Code / Chapter . Code Smells
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Why does this happen?
Programmer
Programmer
smooth-sailing
production code
(in the middle of coding it)
complete
everything
Testable
design
In the middle of coding, a programmer doesn’t
take care testable design
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Why does this happen?
Programmer
Programmer
It works!
production code
(It’s done)
complete
everything
Hard-to-
Test Code
No test code is often difficult to write tests
But untestable
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Feel test painful
https://unsplash.com/photos/_cbKur I A
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Summary “ . Causes of test painful”
• There are various causes of test painful
• Focus on two causes
.Too much bother to write tests
.Hard-to-Test Code
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Agenda
.Causes of test painful
.Test-Driven Development
.How to Use Test-Driven Development
.Summary
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https://unsplash.com/photos/jNrGkkvYk
TDD
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Test-Driven Development (TDD)
• The goal of TDD is “Clean code that works”
• A way of managing fear during programming
• Drive development by automated testing
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Don’t write a line of new code
unless you first have a failing
automated test
Eliminate duplication
TDD Rules
https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
KentBeck_TDD_byexample.pdf
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TDD Cycle “Red-Green-Refactor”
RED
REFACTOR GREEN
. Failed test
. Passed
. Refactor
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TDD Cycle
.Add a little test
.Run all tests, and fail
.Make a little change
.Run all tests and succeed
.Refactor to remove duplication
https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
KentBeck_TDD_byexample.pdf
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TDD steps
.Make a to-do list to remind us what all we
need to do
.Work on the TDD cycle
• “Temporary implementation” for changing
from red to green quickly
• Add to-do you notices along the way
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DEMONSTRATION
https://unsplash.com/photos/xt tb oa o
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by CakePHP .
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To-do list
Article details API
• Article details API request returns success
response
• Article details API returns article resource
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© - BASE, Inc.
. Add a little test
RED
REFAC
TOR
GREEN
DEMO
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Possibly related to
Cake\Controller\Exception\MissingActionE
xception: "Action ArticlesController::view()
could not be found, or is not accessible."
. Run all tests, and fail DEMO
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. Make a little change
RED
REFAC
TOR
GREEN
DEMO
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OK ( test, assertion)
. Run all tests and succeed DEMO
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To-do list
Article details API
• Article details API request returns success
response
• Article details API returns article resource
DEMO
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. Add a little test
RED
REFAC
TOR
GREEN
DEMO
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Failed asserting that '[]'
matches JSON string
“{ }”.
. Run all tests, and fail DEMO
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. Make a little change
RED
REFAC
TOR
GREEN
DEMO
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OK ( test, assertion)
. Run all tests and succeed DEMO
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. Refactor
RED
REFAC
TOR
GREEN
DEMO
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. Refactor
RED
REFAC
TOR
GREEN
DEMO
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To-do list
Article details API
• Article details API request returns success
response
• Article details API returns article resource
DEMO
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Principles for TDD: “ -As” pattern
• Use separate code paragraphs for each of the
As.
• -As
• Arrange: variable declaration and initialization
• Act: invoking the code under test
• Assert: verify that expectations
• This pattern makes it easy to revisit test code
https://integralpath.blogs.com/thinkingoutloud/ / /principles_of_t.html
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Summary “ . Test-Driven Development”
• The goal of TDD is “Clean code that works”
• TDD cycle “Red-Green-Refactor”
• Make a todo list and drive TDD cycle
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Agenda
.Causes of test painful
.Test-Driven Development
.How to Use Test-Driven Development
.Summary
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. No knowledge how to write tests
. Too busy projects
. No test code in production code
. Too much bother to write tests
. Hard-to-Test Code
. Unmaintainable test codes
- Causes - - Possibly solutions -
. Learn how to write tests
. Improve project management
. Legacy code improvement
. Write the tests first
. Testable code design
. Tests with high readability and
maintainability
FOCUS ON
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© - BASE, Inc.
TDD solves two causes of test painful
TDD
• Test First
• TDD Cycle
Hard-to-Test Code
Too much bother
to write tests
- Causes -
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© - BASE, Inc.
TDD solves the cause “Too much bother to write tests”
TDD
• Test First
• TDD Cycle
Hard-to-Test Code
Too much bother
to write tests
- Causes -
Write the tests
in TDD cycle
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© - BASE, Inc.
Too much bother to write tests
• In most cases, a programmer write test codes
after writing production codes
Programmer
Write
production codes
Write
test codes
BEFORE
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Too much bother to write tests
• Write test codes and production codes in TDD
cycle
• Write the tests first
Programmer
AFTER
RED
REFACT
OR
GREEN
Write
production codes
Write
test codes
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TDD solves the cause “Hard-to-Test Code”
TDD
• Test First
• TDD Cycle
Hard-to-Test Code
Too much bother
to write tests
- Causes -
Listening to the Tests
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Listening to the tests
• TDD is about feedback on the code’s internal
qualities
• ex. coupling cohesion of classes, dependencies, effective information
hiding
Freeman, Steve. Growing Object-Oriented Software, Guided by Tests
Chapter . Listening to the Tests
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Hard-to-Test Code
Programmer
Programmer
It works!
production code
(It’s done)
complete
everything
UnTestable
design
No test code is often difficult to write tests
But untestable
BEFORE
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© - BASE, Inc.
Hard-to-Test Code
Programmer
Programmer
production codes
(with test codes)
complete
everything
Testable
design
They becomes to be careful to make codes
testable
AFTER
RED
REFACT
OR
GREEN
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CASE STUDIES
https://unsplash.com/photos/oBI NBP Lhg
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Can’t replace dependencies
Bloated class/function
Case studies
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Can’t replace dependencies
Bloated class/function
Case studies
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Example
• A method to charge on order
• Includes communication to external payment
services
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Hard-to-Test Code BEFORE
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Hard-to-Test Code BEFORE
It’s difficult to inject CardCharge class
We can’t replace the dependency
(without Magic)
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. Write a little test AFTER
• Consider Dependency
Injection to write a test
• It is one of benefits to
write a test first
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Can’t replace dependencies
Bloated class/function
Case studies
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Example
• A controller action to handler order charge
request
• Save order resource
• View order page
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Hard-to-Test Code BEFORE
• A controller action
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Hard-to-Test Code BEFORE
• Handle both requests
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Hard-to-Test Code BEFORE
• The business logic in it
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Hard-to-Test Code BEFORE
• Also there are another
concerns
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Hard-to-Test Code BEFORE
Mixed multiple use cases (request)
Many procedures
Hard-to-Test business logic code
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Make a to-do list
• View the order page
• Redirect when saving an order is succeeded
• Calculate total amount of an order
• Save order resource
• Send charge request to external payment
service
• etc
AFTER
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Run TDD cycle for each to-do
• View the order page
• Redirect when saving an order is succeeded
• Calculate total amount of an order
• Save order resource
• Send charge request to external payment service
• etc
AFTER
RED
REFACT
OR
GREEN
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For instance
• View the order page
• Redirect when saving an order is succeeded
• Calculate total amount of an order
• Save order resource
• Send charge request to external payment service
• etc
AFTER
RED
REFACT
OR
GREEN
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Calculate total amount of an order
• This is a important logic, so many test patterns
are needed
• It may be better to write it in Entity
AFTER
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. Write a little test AFTER
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Business logic in Model AFTER
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“Your designs must consist of many highly
cohesive, loosely coupled components, just to
make testing easy”
https://www.eecs.yorku.ca/course_archive/ - /W/ /sectionM/case_studies/money/
KentBeck_TDD_byexample.pdf
A benefit of TDD
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© - BASE, Inc.
Summary “ . How to Use Test-Driven Development”
• TDD solves two causes of test painful
.Too much bother to write tests
.Hard-to-Test Code
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© - BASE, Inc.
Agenda
.Causes of test painful
.Test-Driven Development
.How to Use Test-Driven Development
.Summary
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TDD solve test
painful
https://unsplash.com/photos/jvBXiynINGE
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Test is a design tool
https://unsplash.com/photos/IClZBVw W A
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The solution to the problem of costly tests,
however, is not to stop testing but instead to get
better at it.
Metz, Sandi. Practical Object-Oriented Design / Chapter Designing Cost-Effective Tests
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Any Questions?