public function testEnable()
 {
     // Find it (en vain …)
     $this->assertNotContains('Quux', Features::getEnabled());
     $this->assertFalse(Features::isEnabled('Quux'));
     // Enable it
     Features::enable('Quux');
     $this->assertTrue(Features::isEnabled('Quux'));
     $this->assertContains('Quux', Features::getEnabled());
     // Disable it
     Features::disable('Quux');
     $this->assertFalse(Features::isEnabled('Quux'));
     // Count it
     $this->assertContains('Quux', Features::getAll());
     $this->assertContains('Quux', Features::getAvailable());
     $this->assertNotContains('Quux', Features::getEnabled());
 }