Behat for Characterization Tests

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for
characterization tests

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Imagine this…

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$$$

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$$$
$$$
$$$

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$$$ Billing Rating
Auth Report
Masking Encoding
$$$
$$$

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$$$
$$$
$$$
Billing Rating
Auth Report
Masking Encoding
public function provides()
{
return [Client ::class];
}

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#phpworld

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#phpworld
$ ls -l test
total 0

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https://twitter.com/brianwisti/status/503987766032494592
YOU ARE IN A LEGACY CODEBASE
> RUN TESTS
YOU HAVE NO TESTS
> READ SPEC
YOU HAVE NO SPEC
> WRITE FIX
YOU ARE EATEN BY AN ELDER CODE HACK.

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#phpworld
Imagine

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Hello, I’m Michael

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#phpworld
@mheap

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#phpworld

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#phpworld
Today

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#phpworld
What is legacy code?

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Michael Feathers - Working Eﬀectively with Legacy Code
“code without tests”
Legacy Code is

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Legacy Code is
“valuable code that
we feel afraid to
change”
JB Rainsberger - Surviving Legacy Code with Golden Master and Sampling

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#phpworld
What if I make a change
and break something?

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What if I make a change
and change something?

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#phpworld
Intended
or
Unintended

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#phpworld
But there aren’t
any tests!

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#phpworld
class SalesUtil {
const BQ = 1000.0;
const BCR = 0.20;
const OQM1 = 1.5;
const OQM2 = self ::OQM1 * 2;
static public function calculate($tSales) {
if ($tSales <= static ::BQ) {
return $tSales * static ::BCR;
} else if ($tSales <= static ::BQ*2) {
return static ::BQ * static ::BCR +
($tSales - static ::BQ) * static ::BCR * static ::OQM1;
} else {
($tSales - static ::BQ) * static ::BCR * static ::OQM1 +
($tSales - static ::BQ * 2) * static ::BCR * static ::OQM2;
}
}
}

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#phpworld
use PHPUnit\Framework\TestCase;
class SalesUtilTest extends TestCase
{
public function testX()
{
$this ->assertEquals(null, SalesUtil ::calculate(1000));
}
}

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#phpworld
{
{
}
}

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There was 1 failure:
1) SalesUtilTest ::testX
Failed asserting that 200 matches expected null.
/Users/michael/development/oss/characterisation-tests-examples/sales-util/test/SalesUtilTest.php:8
FAILURES!
Tests: 1, Assertions: 1, Failures: 1.

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{
public function testSalesLTE1000Pay20PercentCommission()
{
$this ->assertEquals(200, SalesUtil ::calculate(1000));
}
}

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class SalesUtil {
const BQ = 1000.0;
const BCR = 0.20;
const OQM1 = 1.5;
} else {
}
}
}

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Failed asserting that 500.0 matches expected null.
FAILURES!

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public function test2000Gets500Commission()
{
$this ->assertEquals(500, SalesUtil ::calculate(2000));
}
{
}

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#phpworld
Failed asserting that 380.0 matches expected null.
FAILURES!

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#phpworld
class SalesUtil {
const BQ = 1000.0;
const BCR = 0.20;
const OQM1 = 1.5;
} else {
}
}
}

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#phpworld
Input Expected
0 0
10 2
500 100
1000 200
1001 200.3
1500 350
1982 494.6
1999.9 499.97
2000 500
2001 500.9
5000 3200
7890 5801
10000 7700

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{
$this ->assertEquals(null, SalesUtil ::calculate(-123));
}

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public function testNegativeSalesGivesCommissionIs()
{
$this ->assertEquals(-24.6, SalesUtil ::calculate(-123));
}

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#phpworld
Do not change the
code

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#phpworld
Do NOT change the
code

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https://en.wikipedia.org/wiki/Equivalence_partitioning
What’s the minimum
number of tests?

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#phpworld
We’re half way!
(and we’ve barely mentioned Behat)

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#phpworld
Choosing your
pinch points

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Choose HTTP

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#phpworld
Choose Behat

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Given I have 1 "Red Bucket" in my basket
And I have 2 "Large Spades" in my basket
When I add 1 "Red Bucket" in my basket
Then I should see 2 "Red Buckets" in my basket
And I should see 2 "Large Spades" in my basket

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Be pragmatic

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composer require behat/behat --dev
vendor/bin/behat --init

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Testing a HTTP API

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$username = $_GET['username'] ?? error('username is required');
$key = $_GET['key'] ?? error('key is required');
$validUsers = [
"michael" => "kangar00s",
"oscar" => "phparch17"
];
$validKey = $validUsers[strtolower($username)] ?? error('could not find user',
404);
if ($key !== $validKey){
error('invalid apikey');
}
output([
'success' => 'true',
'user' => ['name' => $username]
]);

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#phpworld
error('username is required');
error('key is required');
error('could not find user', 404);
error('invalid apikey');
output([
'success' => 'true',
'user' => ['name' => $username]
]);
1. Missing username
2. Missing key
3. Invalid username
4. Invalid key
5. Successful authentication

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Scenario: No Username
When I make a "GET" request to "/"
Then the response status code should be "400"
And the "error" property equals "username is required"

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Scenario: No API Key
When I make a "GET" request to "/?username=foo"
And the "error" property equals "key is required”

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Scenario: Invalid Username
When I make a "GET" request to "/?username=bananas&key=foo"
And the "error" property equals "could not find user”
Scenario: Invalid API Key
When I make a "GET" request to "/?username=michael&key=foo"
And the "error" property equals "invalid apikey"

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Scenario: Successful login
When I make a "GET" request to "/?username=michael&key=kangar00s"
And the "success" property equals "true"
And the "user.name" property equals "michael”

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More complex tests

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Given that header property "X-CustomAuthKey" is "Secret123"
And that header property "Accept" is "application/json+vnd.v2"
And that the request body is valid JSON
'''
{
"alpha":"beta",
"count":3,
"collection":["a","b","c"]
}
'''
When I make a "POST" request to "/account/balance"
And the "X-Remaining" header property equals "18"
And the "balance.usd" property equals"1832.54"
And the "balance.gbp" property equals "13.99"
And the "balance.eur" property equals "19422.18"

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Then the response status code should be “200"
And the response body contains the JSON data
'''
{
"in_credit": true,
"balance": {
"usd": 1832.54,
"gbp": 13.99,
"eur": 19422.18
}
}
'''

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And the value of the "balance.usd" property matches the pattern “/^\d{1,3}\.
\d{2}$/"
And the value of the “last_updated” property matches the pattern "/^[0-9]{4}
[\-][0-9]{2}[\-][0-9]{2} [0-9]{2}[:][0-9]{2}[:][0-9]{2}$/"

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composer require datasift/testrest-extension

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# behat.yml
default:
extensions:
DataSift\BehatExtension:
base_url: "http: //localhost:8080/"
suites:
default:
contexts:
- 'DataSift\BehatExtension\Context\RestContext'

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HTTP Mocks

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function get_balance($username) {
return $client ->get(
“http: //localhost:88/billing/check_balance/".$username
) ->getBody();
}
$balance = get_balance($username);
if ($username != 'michael') {
error('wrong username');
}
if (!$balance['has_credit']) {
error('no credit remaining');
}
success(['data' => 'valid account'])

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Mountebank

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npm install -g mountebank

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Given Mountebank is running
And a mock exists at "/billing/check_balance" it should return
"200" with the body:
'''
{ "has_credit": false, "credit_limit": 0 }
'''
And the mocks are created
When I make a "GET" request to "/auth?username=michael"
And the response is JSON
And the response body JSON equals
'''
{ "error": "no credit remaining" }
'''

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#phpworld
Given Mountebank is running
And a mock exists at "/billing/check_balance" it should return
"200" with the body:
'''
{ "has_credit": true, "credit_limit": 10000 }
'''
And the mocks are created
When I make a "GET" request to "/auth?username=michael"
And the response is JSON
And the response body JSON equals
'''
{ "data": "valid account" }
'''

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Automating a browser

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#phpworld
$ composer require --dev behat/mink-extension
$ composer require --dev behat/mink-selenium2-driver
$ java -Dwebdriver.chrome.driver=chromedriver -jar selenium-
server-standalone-3.7.1.jar

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#phpworld
# behat.yml
default:
extensions:
Behat\MinkExtension:
base_url: 'https: //wikipedia.org'
sessions:
default:
selenium2:
browser: "chrome"
suites:
my_suite:
contexts:
- \Behat\MinkExtension\Context\MinkContext

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Scenario: Searching for a page that does exist
Given I am on "/wiki/Main_Page"
When I fill in "search" with "Behavior Driven Development"
And I press "searchButton"
Then I should see "agile software development"

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Custom Steps

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When I fill in "search" with "Behavior Driven Development"
And I press "searchButton"

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When I search for "Behavior Driven Development"

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1 scenario (1 undefined)
3 steps (1 passed, 1 undefined, 1 skipped)
0m3.63s (10.62Mb)
>> my_suite suite has undefined steps. Please choose the context to generate
snippets:
[0] None
[1] FeatureContext
[2] Behat\MinkExtension\Context\MinkContext

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#phpworld
[0] None
[1] FeatureContext
> 1
--- FeatureContext has missing steps. Define them with these snippets:
/**
* @When I search for :arg1
*/
public function iSearchFor($arg1)
{
throw new PendingException();
}

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./vendor/bin/behat --append-snippets

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[0] None
[1] FeatureContext
> 1
u features/bootstrap/FeatureContext.php - `I search for "Behavior Driven
Development"` definition added

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Feature: Test
TODO: write pending definition
1 scenario (1 pending)
3 steps (1 passed, 1 pending, 1 skipped)
0m2.23s (10.61Mb)

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/** @BeforeScenario */
public function gatherContexts(
Behat\Behat\Hook\Scope\BeforeScenarioScope $scope
) {
$environment = $scope ->getEnvironment();
$this ->minkContext = $environment ->getContext(
'Behat\MinkExtension\Context\MinkContext'
);
}

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/**
* Fills in form field with specified id|name|label|value
* Example: When I fill in "username" with: "bwayne"
* Example: And I fill in "bwayne" for "username"
*
* @When /^( ?:|I )fill in "(?P( ?:[^"]| \\")*)" with "(?P( ?:[^"]|
\\")*)"$/
* @When /^( ?:|I )fill in "(?P( ?:[^"]| \\")*)" with:$/
* @When /^( ?:|I )fill in "(?P( ?:[^"]| \\")*)" for "(?P( ?:[^"]|
\\")*)"$/
*/
public function fillField($field, $value)
{
$field = $this ->fixStepArgument($field);
$value = $this ->fixStepArgument($value);
$this ->getSession() ->getPage() ->fillField($field, $value);
}

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/**
* Presses button with specified id|name|title|alt|value
* Example: When I press "Log In"
* Example: And I press "Log In"
* @When /^( ?:|I )press "(?P( ?:[^"]| \\")*)"$/
*/
public function pressButton($button)
{
$button = $this ->fixStepArgument($button);
$this ->getSession() ->getPage() ->pressButton($button);
}

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/**
* @When I search for :term
*/
public function iSearchFor($term)
{
$this ->minkContext ->fillField('search', $term);
$this ->minkContext ->pressButton('searchButton');
}

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#phpworld
$ ./vendor/bin/behat
Feature: Test
1 scenario (1 passed)
3 steps (3 passed)

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#phpworld
When I make a "GET" request to "/?username=michael&key=kangar00s"

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When I log in as "Michael" with the password "kangar00s"

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Snapshot testing

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#phpworld
public function toJson(){
return json_encode(["id" => $this ->id]);
}
——
public function test_json_formatting_is_correct() {
$order = new Order(1);
$this ->assertMatchesSnapshot($order ->toJson());
}

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#phpworld
$ ./vendor/bin/phpunit
There was 1 incomplete test:
1) ExampleTest ::test_json_formatting_is_correct
Snapshot created for ExampleTest __test_json_formatting_is_correct

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#phpworld
OK (1 test, 1 assertion)

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public function toJson(){
return json_encode(["id" => 'Q'.$this ->id]);
}

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#phpworld
1) ExampleTest ::test_json_formatting_is_correct
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'{"id": 1}'
+'{"id": "Q1"}'
FAILURES!

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@mheap
#phpworld
https: //github.com/spatie/phpunit-snapshot-assertions

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Behat for Characterization Tests

Behat for Characterization Tests

Michael Heap

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