A Comprehensive Tutorial on Manual Testing Techniques and Best Practices – Black Box Testing Technique!

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Hey all,

In this blog, I will let you know about the Black Box testing. And I am sure That I will enjoy it a lot after seeing my knowledgeful blog.

Black Box Testing.

Black box testing is a functional and verification-checking type of testing. During this testing, a tester does not have any idea about the internal testing process; they simply perform testing based on verification and validation work. According to the black box tester, they conduct testing relying on their mind and experience, without possessing any coding knowledge for testing, and they are unable to use automation tools. They solely rely on their brilliant experiences to perform the testing.

In a simplified manner, black box testing provides assurance for software and products. Its primary goal is to ensure that the software aligns with your client’s expectations and satisfaction.

How to conduct the Black Box Testing?

Black box testing can be done in the following ways: 

1 Syntax-Driven Testing

Syntax Testing is a black-box testing technique that focuses on testing the format and structure (syntax) of data inputs and outputs of a system. It is performed to ensure that the structure of your software is robust, and the software delivers correct and valid outputs to the clients. This testing technique basically checks whether the test cases are generated so that each grammar rule is used at least once.

2 Equivalence partitioning

Many types of functions and inputs function similarly, and we have generated the same test cases in the table. During this testing process, the aim is to reduce the number of test cases that need to be executed by identifying a small number of test cases that will effectively cover all valid and invalid input values.

Equivalence Partitioning helps testers focus on testing the software and verifying the validity of inputs. It involves dividing test cases into different classes or partitions.

In the Equivalence Partitioning technique, there are four steps that we have to follow.

  1. Identify input variables: Determine the input variables that the software unit takes.
  2. Divide input variables into equivalence classes: For each input variable, identify groups of data that are expected to produce the same behavior from the software unit. These groups are called equivalence classes.
  3. Create test cases: For each equivalence class, create a test case that uses a value from the class as input.
  4. Execute test cases: Run the test cases against the software unit and record the results.

3 Boundary value analysis

Boundary Value Analysis (BVA) is a black-box testing technique that focuses on testing the behavior of a software system at the boundaries of its input domain. The aim of this testing technique is to ensure that the system’s boundary values accept valid inputs and that the performance of the boundary yields accurate results.

4 Cause-effect graphing

By using the cause-effect graphing technique, you can present the combinations of your inputs graphically, and you can convert it into a decision table to obtain the test cases. The main advantage of this technique is that the boundary value of the software and equivalence class partitioning methods may not yield accurate results, as they may not consider the valid input combinations.

Mainly, it can help us create our test cases in graph mode, eliminating the need to create multiple test cases, as we can represent our results graphically.

The following steps are followed:

  1. Identify inputs (causes) and outputs (effect).
  2. Develop a cause-effect graph.
  3. Transform the graph into a decision table.
  4. Convert decision table rules to test cases.

For example, in the following cause-effect graph:

It can be converted into a decision table like:

5 Requirement-based testing

First of all, this is my favorite testing technique, and it is also a black-box testing technique. During this testing, a tester doesn’t need to know the internal details of the software. The tester will perform testing based on functional and non-functional aspects, and that’s it.

If all the functions are working well, then verification and validation testing can be conducted. After completing these tests, you can say that the Requirement-based testing process is finished. If the software meets the customer’s requirements, it means we are developing good software that users can use.

6 Compatibility testing

In this testing technique, we can ensure whether my software or application is running well in different hardware, operating systems, browsers, network environments, and mobile devices. The main purpose of this testing is to provide a report if the software does not perform well on any device or in other environments.

Some parameters that generally affect the compatibility of software are:

  1. Processor (Pentium 3, Pentium 4) and several processors.
  2. Architecture and characteristics of machine (32-bit or 64-bit).
  3. Back-end components such as database servers.
  4. Operating System (Windows, Linux, etc).

What are the types of black box testing?

  1. Functional Testing 
  2. Regression Testing
  3. Nonfunctional Testing (NFT) 

Functional Testing

The meaning of functional testing is to ensure that all functions are working well or not. In other words, functional testing is basically used to test the software functions because our customer will add multiple functions to the software. Due to this, we have to verify that the newly added functions are working well or not. That’s why we need to do functional testing.

Regression Testing

In Regression Testing, we identify whether the newly added functions are working or not. We all know that if we add a new function, it might impact other functions that haven’t been validated. For this reason, we conduct the Regression Testing process to understand the details of the software updates.

Nonfunctional Testing (NFT) 

In this testing technique, we find the non-functional activities in the software. As we all know, during the development process, not all functions are working, and because of this reason, our software may not perform optimally and may not meet the client’s expectations. That’s why we have to undergo the Non-Functional testing process to understand the status of non-functional features or activities.

Tools are used in black Box testing.

  1. Appium
  2. Selenium
  3. Microsoft Coded UI
  4. Applitools
  5. HP QTP.

What can be identified by Black Box Testing

The black box testing method is a software testing technique. In this testing, a tester conducts tests based on their own knowledge and experiences, following the Software Development Life Cycle (SDLC) testing process to achieve results. In black box testing, a tester does not perform internal testing as they lack knowledge of coding, and they are unable to use automation tools.

They focus solely on external testing activities such as function testing, verification, validation, and other types of black box testing. This approach is particularly useful for testing applications where the tester does not have access to the source code or internal documentation.

Black-box testing can be used to identify a wide range of software defects, including:

Incorrect or missing functionality: If the software does not perform according to the intended function, we need to check whether we missed entering the correct code or not. This is why we need to identify any missing functions during this testing.

Interface and usability problems: In simpler terms, if your software has a poor-quality interface and design, users may struggle to use it. The low quality and unclear design don’t guide users on how to navigate or use the software effectively, leaving them confused about its usage.

Data handling errors: By conducting data handling error testing, we can identify where the data is causing poor performance and understand why certain functions cannot be used effectively.

Security vulnerabilities: Black-box testing can reveal security vulnerabilities, including but not limited to input validation flaws, insecure data storage, and vulnerabilities to cross-site scripting (XSS) attacks.

Performance and scalability issues: Let’s understand this issue. Performance and scalability issues are very dangerous because if the software cannot perform well, it becomes a waste for everyone. People will not use this software because of its poor performance, making it unable to handle any work efficiently.

For this reason, we conduct performance and scalability testing to understand the state of the software.

Error handling and fault tolerance: One of the basic challenges in every software or product is dealing with errors. Let me explain in a simple way: every software has some errors or complications, and these issues can hinder the product’s performance in front of users or during testing. To ensure that our confidence remains intact, it’s essential to conduct testing on error handling and fault tolerance. This helps us identify, address, and prevent potential problems, ensuring a more resilient and reliable software or product.

Compatibility issues: Black-box testing can help to ensure that the software runs correctly across different hardware, operating systems, browsers, and mobile devices.

Advantages and Disadvantages of Black Box Testing

S.noAdvantages of Black-Box TestingDisadvantages of Black-Box Testing
1No knowledge of internal code is required, making it accessible to testers without programming expertise, and they don’t want to use automation tools.Difficulties in designing effective test cases: Without understanding the internal workings, designing comprehensive tests can be challenging.
2Focuses on the user perspective: Tests the software as a user would, uncovering usability and functionality issues.Time-consuming: Testing all possible inputs and outputs can be time-intensive, especially for complex systems.
3Efficient for large systems: Testing complex systems without the need to understand intricate code details.May not cover all defects: It’s difficult to design test cases for specific internal logic or edge cases.
4Unbiased and independent: Separates testing from development, potentially leading to more objective assessments.Limited debugging information: Identifying the root cause of defects may be harder without access to internal code.
5Early detection of defects: Identifies issues before code review or white-box testing, saving time and effort.Difficult to test complex algorithms: Black-box testing may not be suitable for testing intricate logic or algorithms.
6Improves software quality: Ensures compliance with requirements and user expectations, leading to better software.Overreliance on requirements: Poorly defined requirements can lead to ineffective test cases and inaccurate assessments.
7Wide range of techniques available: Equivalence partitioning, boundary value analysis, decision tables, etc., offer diverse testing approaches.Potential for redundant testing: Testing functionality already covered by white-box testing can be inefficient.


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