The why and how of manual testing in agile development

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Organizations use many methodologies and tools to test their product for bugs and issues. Most businesses follow pre-defined and time-tested approaches and tools to guarantee good quality. Then, there are those who put aside structure and processes for intuition and gut.

Two radically different testing methods to test software release schedules are exploratory testing and scripted testing. While exploratory testing gives testers the freedom to use their instinct, skills, and experience for detailed testing, scripted testing requires testers to follow a series of guidelines to verify if the actual result is as intended.

So, what’s the real difference between the two methods? Which makes more sense?

Exploratory testing

Exploratory testing, a learning approach to software testing, emphasizes the personal freedom and responsibility of each individual tester. Exploratory testing can be applied to any test technique, at any stage in the development process. As the software is tested, individual testers may learn new things. This, when combined with their experience and creativity can drive new and improved tests that can enhance product quality.

The key aspect of exploratory testing is not the test technique being used or the product being tested, but the skills and experience of individual testers. Since exploratory testing is highly dependent on the tester’s skill in inventing test cases and detecting defects, the more skilled the tester, the better the outcome.

Scripted testing

Scripted testing requires testers to follow a detailed step-by-step approach to test a specific functionality. It requires testers to define test cases in advance with instructions that explain the expected results of the test. Testers must follow the steps. They have a clear idea about what should happen at the end of the test. Testers are clearly instructed to follow a sequence of steps with minimal deviation from the script. Scripted testing ensures that each and every piece of functionality is tested and passed. It confirms that all deliverables are met.

However, scripted testing is a time-intensive methodology; if the steps are too specific, they can become invalid or irrelevant with product evolution.

Exploratory testing vs. scripted testing

Although exploratory testing and scripted testing are clearly different, they aim for similar testing effectiveness. When performing exploratory testing, the expectations are open. While some results may be as predicted, others may not. When performing scripted testing, the test cases are designed in advance; all the testers need to do is compare the actual resulted with the expected result.

Here’s a comparison between the two approaches:

Exploratory testing

Scripted testing

1 Is more a mindset. Is a formal testing methodology or approach.
2 Suitable when requirements and specifications are incomplete. Suitable when requirements and specifications are complete.
3 Works well even if requirements or deliverables evolve. Does not work well if requirements or deliverables change frequently.
4 Less preparation is needed to devise test cases. Substantial preparation is needed to devise test cases.
5 Testers can use logical reasoning, based on previous results, to guide future testing. Testers must follow step-by-step instructions and are not allowed deviations.
6 Extremely stimulating for the tester and they usually feel more involved in the process. Since testers just have to follow guidelines, involvement levels are lower.
7 Bugs can be detected quickly. Bugs are only detected at the end of the test cycle.
8 Works well if testers are pressed for time. Does not work well with time constraints.
9 Dependent on the skills and abilities of the tester. Independent of the skills and abilities of the tester.
10 Highly effective if testers are skilled as it gives them the flexibility to test as they build. Highly effective if aspects or values that need to be checked are in a sequence.
11 Testers can alter tests on the fly. Testers have to follow a sequence of test cases that have been designed in advance.
12 Enables rapid feedback. Feedback is slower.
13 Since testing is performed on-the-fly, test cases cannot be reviewed in advance. All test scripts and test cases are designed and reviewed in advance.
14 Since tests are unlikely to be exactly repeatable, new bugs or errors can emerge. Since the same tests are repeated, chances of new bugs or errors being overlooked are higher.
15 There is no way to confirm that all the requirements have been met. At the end of the testing cycle, testers can clearly confirm if all the requirements have been met or not
16 Managing test coverage is challenging. Managing test coverage is easier.
17 Makes it difficult to identify the tests that have been run. Detailed information on the tests that have been run is available.
18 Without documentation, repeating the same test can prove challenging. Since all test scripts are defined in advance, the same tests can be repeated.
19 It cannot be automated. It can be automated.
20 Testers do not know what to expect at the end of the testing cycle. Testers know what to expect at the end of the testing cycle.

Better together

Clearly, scripted testing can only lead a tester to the desired result. It is not concerned about what is learned in the process -only that the desired result is achieved. Since this type of approach can severely limit learning in a testing environment, many potential problems that real-world users might encounter may never get caught by scripted testing. When combined with exploratory testing, however, the impact could be greater. By testing the product – beyond the script and driven by the testers’ skill and gut, testers can get fresh insights into product quality that scripted tests would have missed completely.

The main aim of any testing methodology is to ensure that the end product is bug-free. As we have seen, exploratory and scripted testing have their own benefits and drawbacks. Effective testing must be a combination of both approaches.

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