Advancements in process technology have enabled the creation of chips with billions of transistors, significantly enhancing power and performance for high-performance computing (HPC) and AI applications. This complexity has spurred the development of various 3D integration and packaging techniques utilizing multi-die/chiplet-based designs. Advanced 3D integration technologies allow for the construction of multi-die systems, each offering specific advantages and trade-offs in terms of performance, application, and cost. Similar to traditional chips, all 3DICs must be rigorously tested for manufacturing defects. This includes Known-Good Die (KGD) testing before stacking, Known-Good-Stack (KGS) testing after stacking, final tests, and system-level tests. Furthermore, given the complexity of the stacking process, in-silicon monitoring solutions are necessary to continuously check silicon health during in-field operation. This tutorial offers an overview of the advanced packaging technologies and explores the associated test flow challenges. An example of how the 3Dblox open standard simplifies the description of a 3D stack, enabling interoperability between EDA tools and allowing various test optimizations, is presented. Additionally, it covers various Design-for-Test (DFT) schemes, sensors/monitors and embedded test & repair solutions to facilitate efficient testing across different packaging configurations.