[The following is an excerpt from my upcoming book, Mobile Testing: An ASTQB-BCS Foundation Guide, coming out in summer 2018.  This section talks about the important issue of mobile test environments.]

Earlier in this book, I gave the example of my client that gave iPhones to all the sales associates in their stores.  Because of that, they have a fairly homogeneous environment. This is true not only of the client-side, but also the connectivity in the stores (through the in-store Wi-Fi installed by them) and the back-end servers in the stores and in their data centers.

In terms of mobile testing, this homogeneity makes them the exception that proves the rule, as the saying goes.  They don't have to deal with widespread and unpredictable environmental diversity.  What diversity they do have is due to deliberate decisions. For example, they have to depreciate the iPhones, so over time there came to be multiple generations of iPhones in stores.

Alternatively, consider an organization that's building an app for Android devices.  There're a lot of different Android phones out there.  Further, as we discussed earlier, the Android phone vendors continue to add new features, which helps them avoid the commoditization fate that befell the makers of PCs. This constant stream of new features and updates means yet more diversity because you've got to support the previous stuff as well the new stuff and the changed stuff.

So, in general, the level of variation with mobile environments is much higher than PCs or laptops.  People entering mobile testing sometimes make the mistake of thinking, "Okay, it's a smaller screen and a soft keyboard-except when we use a Bluetooth keyboard-so how different could it be from testing PC apps?"  Well, the differences can be very significant and very important for testing.