SLIDE 1
What is it
TDD is a software development approach whereby you write
your test cases before you write any program text
- TDD–2
TTD Test-Driven Development Create a formal, executable - - PowerPoint PPT Presentation
TTD Test-Driven Development Create a formal, executable - - PowerPoint PPT Presentation
TTD Test-Driven Development Create a formal, executable specification of what to do What is it TDD is a software development approach whereby you write your test cases before you write any program text TDD2 What
SLIDE 2
SLIDE 3
What is it – 2
TDD is a software development approach whereby you write
your test cases before you write any implementation program text
You will already have defined the requirement for the class,
an initial specification for the class, and an initial design for the class
- TDD–3
SLIDE 4
What is it – 3
TDD is a software development approach whereby you write your test cases before you write any implementation program text
You will already have defined the requirement for the class, an
initial specification for the class, and an initial design for the class
Tests drive or dictate the order in which the program text is
developed
- TDD–4
SLIDE 5
What is it – 4
TDD is a software development approach whereby you write your test cases before you write any implementation program text
You will already have defined the requirement for the class, an
initial specification for the class, and an initial design for the class
Test cases dictate the order in which the program text is
developed
By the order in which tests are satisfied
- TDD–5
SLIDE 6
What is it – 5
TDD is a software development approach whereby you write your test cases before you write any implementation program text
You will already have defined the requirement for the class, an
initial specification for the class, and an initial design for the class
-
Test cases dictate the order in which the program text is developed
By the order in which tests are satisfied
The intent of the test cases is to
Provide a formal, executable specification of what a the unit
is to do
As a consequence, Some test cases are A part of the specification document for independent features A part of the design document to verify consistent and proper
implementation
- TDD–6
SLIDE 7
TDD stages
Write a single test Compile it – compilation will fail, as you have no
implementation
Implement just enough program text to get the test to
compile
Run the test – see it fail Implement just enough program text to get the test to pass Run the test and it pass Refactor Repeat
TDD–7
SLIDE 8
TDD stages
TDD–8
Write a test Compile Fix compile errors Run test Watch it fail Run program test Watch it pass Run test Watch it pass Refactor & test
SLIDE 9
How does this affect you?
Before you write program text, think about what it will do
TDD–9
SLIDE 10
How does this affect you? – 2
Before you write program text, think about what it will do
Write the test cases that use methods that are not even
implemented yet
TDD–10
SLIDE 11
How does this affect you? – 3
Before you write program text, think about what it will do
Write the test cases that use methods that are not even implemented yet
A test is not something you do it is something you write and
run once, twice, three times, etc. etc. etc.
TDD–11
SLIDE 12
How does this affect you? –
Before you write program text, think about what it will do
Write the test cases that use methods that are not even implemented yet
A test is not something you do it is something you write and
run once, twice, three times, etc. etc. etc.
It is program text – a formal, executable specification You have test automation so you can repeatedly test your
system even after small changes (regression testing)
TDD–12
SLIDE 13
How does this affect you? – 5
Before you write program text, think about what it will do
Write the test cases that use methods that are not even implemented yet
A test is not something you do it is something you write and run once, twice, three times, etc. etc. etc.
It is program text – a formal, executable specification You have test automation so you can repeatedly test your system
even after small changes (regression testing)
If a bug is found after development, a test is created to keep
the bug from coming back
- TDD–13
SLIDE 14
Why TDD?
Programmers dislike testing
TDD–14
SLIDE 15
Why TDD? – 2
Programmers dislike testing
They will test reasonably thoroughly the first time The second time is less thorough The third time ... ??? Good luck – testing is a boring task
TDD–15
SLIDE 16
Why TDD? – 3
Programmers dislike testing
They will test reasonably thoroughly the first time The second time is less thorough The third time ... ??? Good luck – testing is a boring task
But programmers need to produce correct program text
So write the tests first Make it easy to run the tests
TDD–16
SLIDE 17
Why TDD? – 3
Encourages programmers to maintain an exhaustive set of
repeatable tests
TDD–17
SLIDE 18
Why TDD? – 4
Encourages programmers to maintain an exhaustive set of
repeatable tests
Tests live alongside the class under test Tests can be run frequently
After every single change with XP (extreme
programming)
With tool support, tests can be run selectively
Making it reasonable to run relevant tests frequently
TDD–18
SLIDE 19
TDD Benefits
Fewer bugs Program text can be refactored without fear Continuous integration
During development a growing subset of the system always
works
It may not do everything required but what it does do is
right
Program text is more maintainable in that regression testing
will find errors due to recent changes
TDD–19
SLIDE 20
TDD–20
XP approach to testing
The Extreme Programming approach
Follows TDD
Tests are written before the program text itself If the program text has no automated test cases, it is
assumed not to work
A testing framework is used so that automated testing
can be done
SLIDE 21
TDD–21
XP approach to testing – 2
So what is different?
Testing is done extremely frequently
After every change This may be as often as every 5 or 10 minutes
SLIDE 22
TDD–22
XP approach to testing – 3
So what is different?
Testing is done extremely frequently
After every change This may be as often as every 5 or 10 minutes