If the applicant has no clue about a main theoritical answer, don't expect to invent it in that moment. There are typical programming exercises which can be learnt or can be figured out in that very moment. But it is a ridiculous expectation that the candidate will figure out big programming concepts during an interview.
On some interviews I attended it was forbidden to take notes. Some companies told me explicitly (even with privacy statements) that their tests are secrets. Which is... whaaat?
When you are collecting a set of test questions, you should know that it can never be a secret. Just like in a school test or a university test people will take secret notes, remember and write the questions outside, make photos with their smartphones. And yes, they will share it the very next moment. Result: those who get the questions will have advantage over others. The test results won't show the measured skills, it will be distorted by the background of the applicants.
Solution: be open about the questions, make a clear expectation description. Real skills, capabilities cannot be created the night before the test. Some questions and answers may be learned. But is it bad if the applicant learned the answers of 300 typical questions the day before the interview? I think it does not show a bad behaviour, it shows a good capability and a great wish to learn. This is exactly what you want.
It is a common section in CVs and interviews to ask the applicant about motivations of change: “Why do you want to change?”, “Why do you think this company would be a good fit for you?”. I've experienced two harmful attitudes:
- the interviewer would like to hear that it is your favourite technology, it is your dreamjob, you always wanted to do something like this, for an acceptable salary you would do it forever
- the interviewer ignores motivatons, saying “The reason is always the money!” Good professionals have the power to push their salary level higher and higher, it is true. Another reason may be that in these days articles about software engineering talent shortage bubble up every day; talking about governmental programmes, high salary and a good option for career changers, even part-time workers (like mothers). Short chats among some senior programmers often contains mocking about it, saying it is all about the incapable people's belief of easy money. Both are unrespectful and harmful!
An applicant has the right to change on financial reasons and should never be ashamed of that - especially in IT job market where a change may double your salary. It is the employer's responsibility to have a recurring session about the employer's salary.
It is also an illusion to expect brimming enthusiasm from all the applicants. Already obtained knowledge and the wish to evolve knowledge makes a professional - not personal love ahead that area. In the early years of IT, coding was the speciality of academic researchers and enthusiastic, highly educated professionals. That was the world of passion - academic careers have always been and old-school developer tools... they were not satisfying for most people. But it is gone! Coding may be quite fun, it can give you the flow of creation every day. And yes, a whole new, colorful industry was born with great workers who switch their computer off in the end of the working day and do something they really like.
Ideal applicant will have some kind of motivation and interest on the technology and will wish to get good money for the work. It is okay. You have to consider the applicant's motivations and you don't have to reject application if he/she is not crazy about the technology. You should worry about the motivations if the applicant really does not care about the job itself. You should worry too if the applicant cannot express own priorities. It may indicate that he/she has no plans to the future, no concept about professional progress. Most entrants go through this period but after a short period they should be able to choose and plan.
Some employers tend to tell people that after hiring they should stay there at least 2-3 years, otherwise it is a betrayal to accept the job. It is not a very common case but I was surprised how many employers have this manner. A job is a job. You have the right to change and extorted loyality is not acceptable.
It is interesting that I found many articles about the shameful job hoppers around 2010 but articles in the last two years have titles like 10 reasons you have to hire a job-hopper. The reason may be that to be a malicious job-hopper was never a career goal but job-hopper was a trendy buzzword among employers and recruiters. Most people don't accept a job to leave it. They want to work, get a good salary, create something meaningful. And yes, most employers won't accept that a colleague left because he/she made bad decisions.
Be careful about testing trends. Some may tell you to prefer psychological tests, IQ tests, assessment centers, development centers. The classical interview processes are pretty straightforward. The interviewer has simple questions about the profession and without special qualifications or soft skills the suitability of the applicant can be measured.
These special methods may be different. You should ask:
- What do they measure?
- How important the measured skill is for the job? What impact it has in addition to the traditional methods?
- Is this difference relevant in your team?
- How good the method is in measuring this skill?
For example:
IQ tests are pretty trendy, they are available for about ~100 years. But how well do they measure intelligence? Can you prepare yourself and push your points higher? Is intelligence "static"? How do IQ points relate to the quality and amount of your actual work? So many doubts.
And another question: It is clear that you would like to hire a developer who is intelligent. Don't "traditional" tests already test it? Don't they give you a better, complex answer on the applicant's intelligence, professional knowledge, ability to present results?
Use special testing methods only if you know what you want, why you need it and you have professionals to apply these methods.