問53
頻出度★★★
プログラムテストに関する記述として, 適切なものはどれか。
平成21年度 春期 ITパスポート試験 問53
マネジメント系システム開発技術 › システム開発技術
This question's explanation and your answers so far.
解説
問 53
Incorrectア
Incorrect. Software quality is built in during the design and implementation phases; it cannot be added afterwards by testing. Testing is only the process that detects and confirms the quality already built in, and the further upstream a defect lies (requirements definition, design), the higher the cost of fixing it. Therefore the idea that quality is better ensured in the testing phase than improved in the design phase is the wrong way round.
- イ
正解 The correct answer is イ. When a program is modified after testing has been completed, you must confirm not only that the modified part itself was fixed correctly, but also that the modification did not break parts that used to work properly (degradation, that is, regression). So new test data for verifying the modified part is added to the test data that has already been verified, and the whole set is retested. This is the basic procedure of regression testing, and the statement in イ describes exactly this procedure, so it is appropriate. Conversely, if you retest with the new test data only, you cannot detect degradation caused by overlooking the scope of impact.
Incorrectウ
Incorrect. The purpose of testing is not only to confirm normal operation but also to uncover latent defects. Therefore test data that intentionally causes errors, such as unexpected input, boundary values, and invalid data (abnormal-case test cases), must always be included. A test that tries only normal cases cannot confirm how well the program withstands the abnormal input that occurs in real operation.
Incorrectエ
Incorrect. The author of a program tends to design test cases along the lines of their own understanding and assumptions, so cases they did not anticipate drop out of the test design as well, which makes defects easy to miss. To ensure objectivity, it is preferable for a third party other than the author to design and carry out the test cases (or to add a review by a third party).
ここがポイント
- Regression testing: after a program is modified, test data for verifying the modified part is added to the existing verified test data and the whole set is retested, to confirm that no degradation has been caused by side effects of the modification.
- Basic principles of software quality management: quality is built in upstream (in design), tests must include abnormal cases, and testing should bring in the viewpoint of a third party other than the author.
用語