Safely Test Backup

There is no easy way to test, without as you say the ultimate test, which as you so correctly say - if it goes pears shaped ?
This is one of the easiest to understand articles on what tests you can conduct without going to the full measure
How Do I Test Backups? - Ask Leo!

Remember also that if you cannot get into windows, you need a way of booting to recover the image
I do not use the Minitool I use Macrium
Macrium Software | Macrium Reflect Free

I previously used Easeus, but prefer Macrium.
It is regularly updated.
I have also made a Macrium recovery method.

On many image creating softwares, the image must be on the root of the external drive, if you put it in a folder, on the drive it will not be seen by the recovery.

I see that Minitool also offers a boot from WinPE

That said on 10 you can get a boot of course from recovery options, forced boot on three failed attempts with power button
or lock screen
Shift and restart if you can get to lock screen
or
Installation USB for 10 from Microsoft

see this for further on that Macrium
Backup and Restore with Macrium Reflect

The points I have covered regarding recovery are also explained on the minitool link here
Restore System Image from External Hard Drive in Windows 10/8/7

Any questions please ask.

EDIT
As explained by my colleague, on his post
VERIFY image is a good first step, but does not indicate that restore of the image is possible. Only that the image is good, as far as the verification is correct.

Hi, if you look at the online manual there is an option to verify images.
MiniTool ShadowMaker Manage - Manage All Your Backup Tasks

Verify: use this option to verify the integrity of the selected backup.
Step 1. Click Verify and you will enter this interface. Select the target backup version and click on Next.

Step 2. The software will begin to verify the selected image file automatically. When this process is finished, please click on OK and Finish to quit this interface

.

Please note, this forum is more focussed on Windows 10; detailed questions about how a program works is better raised in its forum.

To send a feedback to MiniTool:

Write an email and send it to support@minitool.com.
To send a bug report to MiniTool:
If you encounter any problem when using MiniTool ShadowMaker, press Generate a report button, save the report to the selected folder and send it to support@minitool.com. Then we will analyze the problem and reply to you as soon as possible.

If I recover the image to my main drive and something goes wrong I will lose the entire contents of my "C" drive and external drive which would leave me no data!

If restoration fails and you overwrite or delete your existing C: then provided your image is still intact, if the program offers similar features to others, you can mount the image and copy any file you like from it.

Of course, you could imagine scenarios like your backup disk failing while the image is being restored... in which case you would lose data.

Some people use two different imaging schedules for the same partitions, or other ways to create two sets of images, so if one fails, the other remains.

Just use the excellent Macrium Reflect Free instead. This has a verify feature and you can boot the backup image into a virtual machine using the viBoot feature to check you have a working backup.