Pulumi leverages general-purpose programming languages like C# and F# to provision cloud resources, enabling developers to utilize native tools and perform automated infrastructure tests, such as mock-based unit testing. This blog post delves into unit testing Pulumi programs, replacing remote calls with mocks to quickly and deterministically test infrastructure code without cloud dependency. Developers can construct a program to deploy a static website to Azure, using Test-Driven Development (TDD) to iteratively add tests and components. The process involves defining resources like a resource group, storage account, and website files, and verifying properties through unit tests. Mocks are implemented to emulate cloud behavior, addressing challenges such as non-deterministic remote calls and unsupported features like FileAsset conversion. The blog concludes with the successful testing of a static website deployment, emphasizing the speed and flexibility of Pulumi's testing capabilities for infrastructure code.