Bun Test Mocking

Covers Bun's Jest-compatible mocking with mock(), spyOn(), and mock.module() for test doubles. You get standard stuff like mockReturnValue, mockImplementation, and call assertions, plus module-level mocking that works on both local files and node_modules. The spy functionality is clean for checking calls without breaking real behavior, and the mock properties (calls, results, lastCall) give you good introspection. Honestly the most useful part is mock.module() since it handles the hoisting complexity for you. If you're writing Bun tests and need to stub dependencies or track function calls, this covers the patterns without making you dig through docs.