what is testing?
not:
refreshing
compiling
for someone else to do
empirical investigation conducted to provide stakeholders with information about the quality of the product or service under test
tl;dr
the process of executing a program or system with the intent of finding errors
closer...
clean code that works
acceptance testing
integration testing
functional testing
unit testing
acceptance testing
integration testing
functional testing
unit testing
what is a unit?
programmer tests
define what it means for the code to work
why should I test?
predictability
- have a process
- know you are finished
tighter feedback loops
- running code informs decisions
- learn lessons faster
dependability
- build trust
- know immediately when you break something
loose coupling
- easy to test
- not just a buzzword
how do you test?
- setup
- exercise
- verification
- teardown
same process for any language
test methods run in isolation
let's do some ruby
require 'test/unit'
class BillsPlayerTest < Test::Unit::TestCase
def test_to_is_a_tad_bit_hyped
end
end
setup
terrell_owens = BillsPlayer.new
exercise
terrell_owens.overpaid?
verification
assert
other assertions
assert_equal "wide receiver",
terrell_owens.position
assert_not_nil terrell_owens.number
assert_raises InterceptionError do
terrell_owens.miss_route!
end
class BillsPlayerTest < Test::Unit::TestCase
def test_to_is_a_tad_bit_hyped
terrell_owens = BillsPlayer.new
assert terrell_owens.overpaid?
end
end
class BillsPlayerTest < Test::Unit::TestCase
def setup
@terrell_owens = BillsPlayer.new
end
def test_to_is_a_tad_bit_hyped
assert @terrell_owens.overpaid?
end
def teardown
# bills lose, again :[
end
end
so what?
- production errors due to uncomprehensive tests
- often done after the code is written
- if not automated, not preformed frequently
- and so on...
test driven development
you, the developer, write the tests!
write tests before implementation
new code only when an automated test fails
take small steps
the process
- write a test
- watch it fail
- write just enough code to make it pass
let's do this
feedback loop
- red
- green
- refactor
refactor
- eliminate duplication
- rename
- single responsibility
- and so on...
tdd is about design
design is a process, not a phase
think about the interface before implementation
when do I test?
TATFT
the drawbacks
all walk, no talk
easier with a pair
team buy-in
some thoughts...
it's ok not to test!
testing vs. spiking
dependencies
- fakes
- stubs
- mocks
find a coop (or job) that helps you test
ask about policies on testing
TATFT
thanks!
- you
- thoughtbot
- david astels
- ben mabey
- bryan liles