Is there any case law where a defendant was not aware of the unusual danger caused by moisture on the floor into which a plaintiff stepped into?

Was the unusual danger one which the defendant knew or ought to have known? I have no hesitation in holding that the defendant did not know of the moisture on the floor into which the plaintiff stepped at the moment of her misadventure. The question is, ought the defendant to have known of its presence? That question has been phrased into a consideration of whether the plaintiff has “made a prima facie case that the appellant (defendant) should have known of the danger which existed on the day of the accident”: per Martland J. in Hillman v. MacIntosh, 1959 CanLII 4 (SCC), [1959] S.C.R. 384 at 393, 17 D.L.R. (2d) 705.

Ilsley C.J. in Smith v. Provincial Motors Ltd., supra, answered the second question as follows at pp. 412-13: “As to (2), the defendant’s responsible servants did not know of the danger, but I think they ought to have known of it. The occupier ‘ought to know of dangers which are discoverable by the exercise of reasonable care and skill’: Charlesworth on Negligence, 3rd ed., p. 197. It must have been known by the crew entrusted with the responsibility of keeping the yard free of snow and of salting and sanding any ice that was there, that occasionally under certain weather and temperature conditions water would flow from the higher level of the adjoining lot onto the yard in question and that on occasion this water would freeze. It is my opinion that those responsible for the condition of the yard did not exercise reasonable care on the morning of December 31st in ascertaining the condition of the yard and that if they had done so the ice would have been discovered. The temperatures had turned freezing over night. The night before, the temperatures were such that snow melted and water ran, yet no one, so far as the evidence discloses, examined the yard closely to ascertain whether a frozen stream was left which visitors might naturally cross when traversing the space between the gate and the office door. The degree of scrutiny which it was the duty of the servants of the defendant to exercise was, in my opinion, very much higher than that which it was the duty of the plaintiff to exercise. The servants of the defendant knew, or should have known, what might happen on these particular premises, yet they did not, I find, exercise reasonable care to ascertain whether it did happen on the day in question. The plaintiff, on the other hand, was not an occupant of the premises and might much more readily be excused for not noticing the ice.”