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Systems Development: Requirements, Design, Implementation, Testing

Testing

Which of the following librettists got it right with regards to systems development?

Things never are as bad as they seem. –Johnny Mercer (1909-1976), U.S. songwriter. "Dream," Her Highness and the Bellboy, Michael H. Goldsen, Inc. (1944).

Things are seldom what they seem, Skim milk masquerades as cream. –Sir William Schwenck Gilbert (1836-1911), British librettist. Mrs. Cripps (Little Buttercup), in HMS Pinafore, Act 2 (1878), published in The Savoy Operas (1926).

Perhaps Americans are a tad optimistic compared to the more stoic Brits, but Gilbert, of Gilbert and Sullivan fame, got it right: when it's all said and done, systems tend to lag behind customer expectations. Significantly.

We talked about this earlier: in requirements specification, we mentioned that software systems are different from so many other human endeavors because they are intangible: software quality cannot be observed directly. Consequently we are forced to rely on testing to help us determine if a developed system meets its specified requirements–or not.

Testing is best performed as an independent, parallel effort from design and implementation. The test process can be developed by a separate team concurrently using the same base set of requirements. Many organizations do this, especially when the output product is a large scale system with serious consequences for failure.

Process Activities

Testing consists of documentation and execution activities. The major test documents are an optional test requirements document, a test plan, test procedures, and test steps. Like other development documents, these start with a general level of detail and grow into finer details as engineering continues.

Execution, or the performance of actual tests, comes in many flavors. There are private and public executions. Generally testing that is expected to fail is performed in private. But testing designed to prove to the customer that the system was developed as specified is performed in public with the customer witnessing the execution of documented test steps.

Exercise

We will write two of the four test documents, namely the plan and the steps. Some of the steps will be performed in public with a customer witness:

• Armenian
• English

Test Procedure Example

Here is a sample test procedure document. The procedure describes the test environment and each test case. But the detail is not sufficient for a novice to execute the tests. Each sentence in a test case would involve five or six steps that the customer could witness and verify independently:

• sampleTestProcedure.pdf

Study Guides

There is no study guide for this unit. There will be a unit quiz, however.

Lecture Slides

Here are copies of the lecture slides presented during class:

• Armenian
• English

Readings

Each of the listed links will open a new browser window:

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