test old code using dependency injection

test-using-dependency-injection.php

<?php

interface Dep {
	public function has();
}

// i want to test this function and get 100% code coverage
function depends(Dep $dependency) {
	if ($dependency->has()) {
		return true;
	}

	return false;
}

// my actual class always returns true and i can't change this behaviour
class MyRealClass implements Dep
{
	public function has()
	{
		return true;
	}
}

// mock the class returning false
$mockFalse = new class implements Dep {
	public function has()
	{
		return false;
	}
};

$bTest = false;
if (depends($mockFalse) === false) {
	$bTest = true;
}
echo ($bTest ? 'test succeeded' : 'test failed') . "\n";

// mock the class returning true
$mockTrue = new class implements Dep {
	public function has()
	{
		return true;
	}
};

$bTest = false;
if (depends($mockTrue) === true) {
	$bTest = true;
}

echo ($bTest ? 'test succeeded' : 'test failed') . "\n";