Being tested in this is the expected condition
The verse first, because it settles what being tried in your faith means, and it does not mean that something has gone wrong with you. Then the research on what is actually being aimed at.
Qur’an and Sunnah
أَحَسِبَ ٱلنَّاسُ أَن يُتۡرَكُوٓاْ أَن يَقُولُوٓاْ ءَامَنَّا وَهُمۡ لَا يُفۡتَنُونَ
Do people think they will be left alone after saying ‘We believe’ without being put to the test
Qur’an 29:2
وَلَقَدۡ فَتَنَّا ٱلَّذِينَ مِن قَبۡلِهِمۡۖ فَلَيَعۡلَمَنَّ ٱللَّهُ ٱلَّذِينَ صَدَقُواْ وَلَيَعۡلَمَنَّ ٱلۡكَٰذِبِينَ
We tested those who went before them: God will certainly mark out which ones are truthful and which are lying
Qur’an 29:3
Translation: M.A.S. Abdel Haleem, The Qur'an, Oxford University Press, 2004.
What the research says
Dugas MJ, Gagnon F, Ladouceur R, Freeston MH (1998). Generalized anxiety disorder: a preliminary test of a conceptual model. Behaviour Research and Therapy, 36(2), 215 to 226 doi
Sets out intolerance of uncertainty as a central component of chronic worry, and found it distinguished people with generalised anxiety disorder from others. The point that carries over here is that the difficulty is with not knowing itself, rather than with the particular thing that is unknown.
Carleton RN (2016). Into the unknown: A review and synthesis of contemporary models involving uncertainty. Journal of Anxiety Disorders doi
Reviews the models built on uncertainty and argues that the fear of the unknown may sit underneath a wide range of anxiety problems rather than belonging to any one of them. Volume and page numbers are deliberately not printed here, because they were not confirmed in the research behind this course.