interface MyDependency { ZIO<MyDependency, Throwable, String> getValue(); } MyDependency mockDependency = ZIO.mock(MyDependency.class); ZIO.when(mockDependency.getValue()).thenReturn(ZIO.succeed("Mocked Value")); ZIO<String, Throwable, String> result = MyClass.doSomething().provide(mockDependency);