public function testPurgeByCacheKey() { $key = $this->instance->save('fooBar', 'some content'); $this->assertNotFalse($key); $result = $this->instance->read('fooBar'); $this->assertSame('some content', $result); $this->instance->purgeByCacheKey($key); $result = $this->instance->read('fooBar'); $this->assertFalse($result); }