Making the calculations
In a recent interview, Martin Taylor of Texas Instruments discusses testing the TI-Nspire line of scientific calculators.
Martin Rowe -- Test & Measurement World, 7/1/2009 2:00:00 AM
As a senior test automation specialist at Texas Instruments in Dallas, Martin Taylor writes software that tests the embedded software in the company’s TI-Nspire line of scientific calculators. The educational calculators require functional testing, including a test of the graphical display. The same software used in the handheld calculators is also available for a PC or Mac. Martin Rowe spoke with Taylor by telephone to learn more about his work.
Q: How does testing a calculator differ from testing PC software?
A: Methods and tools for automated testing of PC and Mac software are generally available, but when testing embedded devices, every device is different. We need custom test-automation software. We create keystroke events in PC software and send them to the calculator under test over a USB link. We can control the calculator remotely through a test engine that’s built into the device.
| Read a conference paper that Taylor wrote on memory-lead testing. See pages 18 to 22. Read past Test Voices columns at www.tmworld.com/testvoices. |
Q: How do you know the state of the calculator during a test?
A: We can upload an image of the screen to the PC. We used to use this to capture and analyze screen images, but now we upload an XML file that records the device’s state.
Q: Why did you change the way you test the calculator’s response to a keystroke?
A: The design of the user screen changes as we get feedback from teachers and students who use the calculator. To test a screen, we had reference images to which we compared test screen images. When the screen design changed, we needed to update the entire library of screen images. We also had to mask out portions of the screen image from our comparisons. For example, the battery indicator. You never know its state when you run a test. Using an XML representation of the device state, we can get the data we need without using screen images.
Q: Besides the user interface, do you test the calculator’s functions?
A: We write special software builds for the embedded software developers to test internal functions. For example, we can run API (application programming interface) tests as well as functional tests. We have fully automated tests that we run on every software build to make sure that new software doesn’t break existing functions.
Q: How do you generate test reports?
A: When we used screen images as part of our tests, we sent test results to HP Test Director software (formerly from Mercury Interactive). Now, we use an open-source tool called Robot Framework to control the test execution and generate reports in HTML format. We can drill down to individual tests and test steps with a browser. With open-source software, we can make our own upgrades and modifications whenever we want. We’re not tied to releases of a commercial product.
Q. Does your test code run any diagnostics on the calculators?
A. We perform memory-leak analysis. We instrument the memory allocation and deallocation code on the device. The test code looks for suspect lines of code that don’t release memory when they should. We produce charts and graphs of free memory over a long sequence of tests.
No related content found.
- 0 rated items found.
Datasheets.com Electronic Parts & Inventory Search
185 million searchable parts
- Part Number
- Description
- Inventory
- Products
- Manufacturers
View All Webcasts
