An architecture spike in agile methodologies usually implies a software development method, which originates in the extreme programming offshoot of agile. It boils down to determining how much effort is needed to solve a particular problem or discover a workaround for an existing software issue.
So, let us explore the benefits and see how these spikes can help in improving quality and making testing easier—by shifting our attention to the left—challenging the specification at a very early phase, asking questions, and getting the ground ready for sensible software architecture, which will, in turn, improve the testability of our application under test.