Hi @Bob Williams ,
If you are asking whether we can test an alert rule before creating it i.e., before clicking on create alert button, can we have something like test alert button then currently there is no such exact feature supported.
Here is a related feature request that's already raised in the feedback forum. If interested, you may upvote it or else if your use case is different then you may share a new feature request here. In general, Azure feature team would check feasibility of a feature request, prioritize against existing feature backlog, add in roadmap as appropriate and would announce and/or update the related Azure documents once a feature request is addressed.
On the other hand, with the current features, as shown in below screenshot up to some extend we can make sure that the alert rule is going to send us alerts in near future or not by depending on chart that shows up while configuring signal logic. To elaborate with the example shown in below screenshot, if the set alert logic is met i.e., at any given point of time if the value generated is greater than the threshold value then the alert rule monitors it continuously and triggers the action.