Black box

Overheard: Software testing explained

A software system can be tested in two ways. It depends on your point of view. It can be with or without technical knowledge of the system. Léon Meijer, Test-driven development, Unit Test, VSTS, NUnit, TestDriven.NET, whats all this?

Black-box tests can be functional or non-functional, though usually functional. The tester selects valid and invalid input for the test and determines if the output is correct. The tester doesn’t need to have knowledge of the internal structure of the system. Typical black-box test design techniques include:

• Equivalence partitioning; To reduce the number of test cases and select test cases that cover all possible scenarios
• Boundary value analysis Validates input and checks if the input is in the valid range, i.e. if (month > 0 && month < 13)
• Decision table testing Are about if- and switch-statements. Decision tables model conditional logic.
• Pairwise testing Test each pair of input parameters to a method. Simple bugs are triggered by a single parameter, next simplest category of bugs consists of those dependent on interactions between pairs of parameters.
• State transition tables Shows in what state a system moves to, based on the current state and input parameters.
• Use case testing Users work through use cases with the aid to verify that a UI fulfills the needs of its users, as described in the use case model. The tester identifies which use case(s) to test, the actors (users), input, output and system effects and the flows of interest between the use cases.
• Cross-functional testing The work of one person is reviewed by the team as a whole.

Overheard: Datacenter in a box coming to a batcave near you

“Sun and a consortium of other businesses are going to lower Blackbox self-contained computing facilities into a Japanese coal mine to set up an underground datacentre, using up to 50 percent less power than a ground-level datacentre.” Chris Mellor, Sun to set up datacentre in coal mine

Sun Microsystems promoted their ”datacenter in a box” concept earlier this year. The datacenters are basically 20-foot shipping containers with racks of pre-configured servers and storage. The idea is that you’d be able to build a datacenter as big as you need because the Blackboxes are modular units — and because they’re self-contained shipping containers, you could ship them  just about anywhere – including outer space.  

When I first read about Project Blackbox, I was thinking military.  But I hadn’t thought about using caves and abandoned mines for commercial use. Genius.

In the Japan project, the coolant is going to be ground water — a little controversial, but they’re working on getting away from water altogether.  Since the cave’s temperature is a constant 59 degrees F,  the cost of running the underground center is expected to be $9 million less than if it were above ground.