The right-hand side of this diagram is wrong. The arrows need to flow upwards from Coding, you start testing the basic units and start increasing your scope until, at the final testing phase, you conduct UAT.
The final UAT phase is the most important one as that is where the software receives user sign off. If it fails here, the project is delayed/failed. If you start UAT with the majority of bugs not caught at unit or integration testing, then you can guarantee that the project will be delayed/will fail.
Hence - the flow of arrows on the right needs to be reversed.
