Class Constants
When creating a test double for a class, Mockery does not create stubs out of any class contants defined in the class we are mocking. Sometimes though, the non-existence of these class constants, setup of the test, and the application code itself, it can lead to undesired behavior, and even a PHP error: PHP Fatal error: Uncaught Error: Undefined class constant 'FOO' in ...
`
While supporting class contants in Mockery would be possible, it does require an awful lot of work, for a small number of use cases.
We can, however, deal with these constants in a way supported by Mockery - by using creating-test-doubles-named-mocks
.
A named mock is a test double that has a name of the class we want to mock, but under it is a stubbed out class that mimics the real class with canned responses.
Lets look at the following made up, but not impossible scenario:
class Fetcher
{
const SUCCESS = 0;
const FAILURE = 1;
public static function fetch()
{
// Fetcher gets something for us from somewhere...
return self::SUCCESS;
}
}
class MyClass
{
public function doFetching()
{
$response = Fetcher::fetch();
if ($response == Fetcher::SUCCESS) {
echo "Thanks!" . PHP_EOL;
} else {
echo "Try again!" . PHP_EOL;
}
}
}
Our MyClass
calls a Fetcher
that fetches some resource from somewhere -maybe it downloads a file from a remote web service. Our MyClass
prints out a response message depending on the response from the Fetcher::fetch()
call.
When testing MyClass
we don't really want Fetcher
to go and download random stuff from the internet every time we run our test suite. So we mock it out:
// Using alias: because fetch is called statically!
\Mockery::mock('alias:Fetcher')
->shouldReceive('fetch')
->andReturn(0);
$myClass = new MyClass();
$myClass->doFetching();
If we run this, our test will error out with a nasty PHP Fatal error: Uncaught Error: Undefined class constant 'SUCCESS' in ..
.
Here's how a namedMock()
can help us in a situation like this.
We create a stub for the Fetcher
class, stubbing out the class constants, and then use namedMock()
to create a mock named Fetcher
based on our stub:
class FetcherStub
{
const SUCCESS = 0;
const FAILURE = 1;
}
\Mockery::mock('Fetcher', 'FetcherStub')
->shouldReceive('fetch')
->andReturn(0);
$myClass = new MyClass();
$myClass->doFetching();
This works because under the hood, Mockery creates a class called Fetcher
that extends FetcherStub
.
The same approach will work even if Fetcher::fetch()
is not a static dependency:
class Fetcher
{
const SUCCESS = 0;
const FAILURE = 1;
public function fetch()
{
// Fetcher gets something for us from somewhere...
return self::SUCCESS;
}
}
class MyClass
{
public function doFetching($fetcher)
{
$response = $fetcher->fetch();
if ($response == Fetcher::SUCCESS) {
echo "Thanks!" . PHP_EOL;
} else {
echo "Try again!" . PHP_EOL;
}
}
}
And the test will have something like this:
class FetcherStub
{
const SUCCESS = 0;
const FAILURE = 1;
}
$mock = \Mockery::mock('Fetcher', 'FetcherStub')
$mock->shouldReceive('fetch')
->andReturn(0);
$myClass = new MyClass();
$myClass->doFetching($mock);