Ms Harrington felt she was deliberately targeted, refused to take the test and after being told her refusal could lead to dismissal, she resigned.
A week later Ms Nelson wrote a mandatory report to the Education Council, raising the issue of Ms Harrington's potential drug use and her refusal to undergo a compulsory drug test.
Ms Harrington started work at Te Whare Whitinga o Te Ra Early Childhood Centre in May 2016, and her manager wrote a positive employee reference to the tribunal.
The tribunal did note Ms Harrington's refusal to take a drug test "raised legitimate concerns about her fitness to teach" but acknowledged there was "no way of knowing precisely when the teacher's admitted drug use occurred and whether it was a one-off lapse in judgment or a regular habit".
The tribunal found Ms Harrington's behaviour amounted to misconduct and her conduct reflected adversely on her ability to teach.
She was made to take drug tests every three months for a year if she wanted to continue practising as a teacher and to inform her employer of the tribunal's decision.
She was also ordered to pay $1565 towards the Complaints Assessment Committee and 40 per cent of the tribunal's costs.