Weapons in which the energy is provided by nuclear fission or fusion have only twice in history been detonated outside of a controlled test environment, in the Hiroshima and Nagasaki events in World War II.
Since then, the world has nearly gone to nuclear war as a result of international conflict (during the Cuban Missile Crisis) and by accident. There have also been a number of narrowly-averted accidental nuclear detonations. See this timeline for a sobering look at how close we have come.
Will no non-test nuclear weapons be detonated before 2035?
This question will resolve positively if no nuclear weapon is detonated before Jan 1, 2035, outside of controlled tests. Negative resolution could be triggered by:
Deliberate nuclear attack.
Accidental nuclear attack (launched by accident or on the basis of erroneous information.)
Accidental detonation of a weapon.
For these purposes we do not consider a radiological weapon — where any fission/fusion energy is energetically sub-dominant to chemical or other explosives — to constitute a nuclear detonation.
The deliberate detonation of nuclear weapons primarily for non-offensive engineering, mining or other civilian purposes (on Earth or in Space) do not trigger negative resolution.
See our related question Will no non-test nuclear weapons be detonated by start of 2024?