Functional Analysis and Testing

During the initial phase of my career in VLSI, I realised that writing Testcases is equally important as Testbench development. A Testcase in any language be it Verilog, VHDL, SystemVerilog, and UVM is not only used to verify the functional correctness and the integrity of the design but also point out areas where the Testbench could be improved. Below are the most important category of Testcases which are most critical: [1] Functional Tests --> In this type of test, the functionality or feature of an IP/module or a subsystem is verified. [2] Register-based Tests --> RW Tests, RO/WO Tests, Default Read/Hard reset Tests, Soft reset tests, Negative RO/WO Tests, Aliasing, Broadcasting, etc [3] Connectivity Tests [4] Clock and Reset Tests [5] Boot up Tests, wake up sequence, training sequence tests. For eg. In the case of DDR – MPC Training, RD DQ Calibration, Command Bus training, Write leveling, etc [6] Command and Sequence-based Tests. [7] Overlapping and Unallocated Region tests. [8] Back-to-back data transfer-based tests. [9] UPF Tests --> Power domain, Level Shifter, clock gating, voltage domain, etc [10] Code Coverage Tests --> In this test toggle, expression, branch, FSM, and conditional coverage holes are measured, and depending on the holes, tests are being written to completely exercise the DUT. [11] Functional Coverage Tests --> In these types of test categories, the functionality of DUT is being measured with the help of bins. There are several ways to do it. If there are coverage holes, more bins are coded to cover those areas, complex scenarios are covered with cross coverage, and bins of intersect functionality. [12] Assertions are basically a check against the design. Basically, these are insertion points within the design which improve the observability and debugging ability. The above are some of the categorizations of tests that need to be applied while checking a design but to achieve all the above features, testcases are broadly classified into the following two types: [1] Directed Testcase: These are the scenarios that the verification engineers can think of or can anticipate. [2] RandomTestcase: These are the scenarios where the maximum amount of bugs can be caught. The random seeds will hit many different use cases which can not be anticipated earlier and has the probability to catch the design issues. Ideally, random tests can be classified into the following two categories: [1] Corner cases --> This is the bug that is only possible to catch when many different scenarios are processed together or they overlap and the best way to catch this type of scenario is to run more repeated regression with more seeds. [2] Stress testing -->These types of tests are useful to check the performance and the scalability of the DUT under multiple concurrent activities and unpredictable scenarios. #vlsi #asic #electricalengineering #semiconductorindustry

𝐃𝐞𝐞𝐩 𝐃𝐢𝐯𝐞: 𝟔 𝐊𝐞𝐲 𝐓𝐲𝐩𝐞𝐬 𝐨𝐟 𝐀𝐏𝐈 𝐓𝐞𝐬𝐭𝐢𝐧𝐠 🚀 APIs are the gates through which your applications talk to databases, services, and other systems — and testing them properly ensures your software is stable, secure, and functional. Let’s go beyond definitions and look at real examples and how you can practice these testing types yourself. 𝟭. 𝗩𝗮𝗹𝗶𝗱𝗮𝘁𝗶𝗼𝗻 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Check if an API is doing exactly what its specification or requirements promise. Example: Suppose there's an API endpoint for user registration: POST /users. Validation testing would verify that if you send missing fields (say no “email”), the API returns a 400 error with a clear validation message. 𝟮. 𝗣𝗲𝗿𝗳𝗼𝗿𝗺𝗮𝗻𝗰𝗲 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Measure how the API behaves under stress: speed, load, scalability. Example: You simulate 1000 concurrent “GET /product” requests to see if the API slows down or starts returning timeouts. 𝟯. 𝗦𝗲𝗰𝘂𝗿𝗶𝘁𝘆 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Look for vulnerabilities, make sure data is protected and only authorized users can access things. Example: Try SQL injection, broken authentication, or tampering with tokens on your “/order/details” API. Also test whether sensitive fields like passwords or personal data are properly masked or encrypted. 𝟰. 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Test each API endpoint to make sure it behaves as intended for all methods, parameters, inputs. Example: The DELETE /post/{id} should actually delete the post and return a success response when the post exists, and return a 404 when it doesn’t. 𝟱. 𝗥𝗲𝗹𝗶𝗮𝗯𝗶𝗹𝗶𝘁𝘆 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Test consistency over time and under different conditions (e.g. intermittent failures, network issues). Example: Run your API calls continuously over many hours to ensure it doesn’t degrade, leak memory, or crash under long-term use. 𝟲. 𝗜𝗻𝘁𝗲𝗴𝗿𝗮𝘁𝗶𝗼𝗻 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 Test interactions between APIs and other modules/systems — how they work together. Example: Your “login” API calls an authentication service, then returns a token to your “profile” service which fetches user details from a database. Integration testing would check that login → token → profile fetch works end-to-end without breaking. ∗ Start Your API Testing Journey With Postman Tool (Coursera Guided Project) — learn to send GET, POST, DELETE, set assertions in Postman. - https://lnkd.in/gRcXA4SV ∗ Introduction to API Testing (Great Learning, free) — covers fundamentals like JSON, authentication, validation, etc. - https://lnkd.in/gKFyA97r ∗ API Testing and Automation — Pluralsight — deeper course including test automation, integrating APIs into CI/CD workflows. - https://lnkd.in/ggrDHnKV #APITesting #AutomationTesting #SoftwareQA #RESTAPI #Postman #TestAutomation #SecurityTest #QualityAssurance

1. Functional Testing: The Foundation a. Unit Testing: - Isolating individual code units to ensure they work as expected. - Analogous to testing each brick before building a wall. b. Integration Testing: - Verifying how different modules work together. - Similar to testing how the bricks fit into the wall. c. System Testing: - Putting it all together, ensuring the entire system functions as designed. - Comparable to testing the whole building for stability and functionality. d. Acceptance Testing: - The final hurdle where users or stakeholders confirm the software meets their needs. - Think of it as the grand opening ceremony for your building. 2. Non-Functional Testing: Beyond the Basics a. Performance Testing: - Assessing speed, responsiveness, and scalability under different loads. - Imagine testing how many people your building can safely accommodate. b. Security Testing: - Identifying and mitigating vulnerabilities to protect against cyberattacks. - Similar to installing security systems and testing their effectiveness. c. Usability Testing: - Evaluating how easy and intuitive the software is to use. - Comparable to testing how user-friendly your building is for navigation and accessibility. 3. Other Testing Avenues: The Specialized Crew a. Regression Testing: - Ensuring new changes haven't broken existing functionality. - Imagine checking your building for cracks after renovations. b. Smoke Testing: - A quick sanity check to ensure basic functionality before further testing. - Think of turning on the lights and checking for basic systems functionality before a deeper inspection. c. Exploratory Testing: - Unstructured, creative testing to uncover unexpected issues. - Similar to a detective searching for hidden clues in your building.

Demystifying the Software Testing 1️⃣ 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗧𝗲𝘀𝘁𝗶𝗻𝗴: 𝗧𝗵𝗲 𝗕𝗮𝘀𝗶𝗰𝘀: Unit Testing: Isolating individual code units to ensure they work as expected. Think of it as testing each brick before building a wall. Integration Testing: Verifying how different modules work together. Imagine testing how the bricks fit into the wall. System Testing: Putting it all together, ensuring the entire system functions as designed. Now, test the whole building for stability and functionality. Acceptance Testing: The final hurdle! Here, users or stakeholders confirm the software meets their needs. Think of it as the grand opening ceremony for your building. 2️⃣ 𝗡𝗼𝗻-𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗧𝗲𝘀𝘁𝗶𝗻𝗴: 𝗕𝗲𝘆𝗼𝗻𝗱 𝘁𝗵𝗲 𝗕𝗮𝘀𝗶𝗰𝘀: ️ Performance Testing: Assessing speed, responsiveness, and scalability under different loads. Imagine testing how many people your building can safely accommodate. Security Testing: Identifying and mitigating vulnerabilities to protect against cyberattacks. Think of it as installing security systems and testing their effectiveness. Usability Testing: Evaluating how easy and intuitive the software is to use. Imagine testing how user-friendly your building is for navigation and accessibility. 3️⃣ 𝗢𝘁𝗵𝗲𝗿 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 𝗔𝘃𝗲𝗻𝘂𝗲𝘀: 𝗧𝗵𝗲 𝗦𝗽𝗲𝗰𝗶𝗮𝗹𝗶𝘇𝗲𝗱 𝗖𝗿𝗲𝘄: Regression Testing: Ensuring new changes haven't broken existing functionality. Imagine checking your building for cracks after renovations. Smoke Testing: A quick sanity check to ensure basic functionality before further testing. Think of turning on the lights and checking for basic systems functionality before a deeper inspection. Exploratory Testing: Unstructured, creative testing to uncover unexpected issues. Imagine a detective searching for hidden clues in your building. Have I overlooked anything? Please share your thoughts—your insights are priceless to me.

I shipped 274+ functional tests at Amazon. 10 tips for bulletproof functional testing: 0. Test independence: Each test should be fully isolated. No shared state, no dependencies on other tests outcomes. 1. Data management: Create and clean test data within each test. Never rely on pre-existing data in test environments. 2. Error message: When a test fails, the error message should tell you exactly what went wrong without looking at the code. 3. Stability first: Flaky tests are worse than no tests. Invest time in making tests reliable before adding new ones. 4. Business logic: Test the critical user journeys first. Not every edge case needs a functional test - unit tests exist for that. 5. Test environment: Always have a way to run tests locally. Waiting for CI/CD to catch basic issues is a waste of time. 6. Smart waits: Never use fixed sleep times. Implement smart waits and retries with reasonable timeouts. 7. Maintainability: Keep test code quality as high as production code. Bad test code is a liability, not an asset. 8. Parallel execution: Design tests to run in parallel from day one. Sequential tests won't scale with your codebase. 9. Documentation: Each test should read like documentation. A new team member should understand the feature by reading the test. Remember: 100% test coverage is a vanity metric. 100% confidence in your critical paths is what matters. What's number 10? #softwareengineering #coding #programming

When to do functional and reliability tests for a new #hardware product? As early as possible. How many tests? As much as you can afford! Designing something is only a part of the journey. Making sure it can last is a whole another skill. Let’s dive into several #productdevelopment phases and questions to answer on phase 1. Proof of Concept (PoC) ✅ - does it already exist? Can you just buy it? - does it work? Can it do what you want? - what components are needed? - it’s ugly and expensive - can you eventually make it smaller and cheaper? - How much power does it consume? 2. Engineering prototypes (EP) ✅ - what parts need to be sourced and which are custom built? - does it power up? Power measurements - does it do what you want? Functional test - is it easy to use? Beta users tests - does it break easily? What fails first - how many times it can turn on/off. Power cycling. Bonus points: - thermal mode - use thermal camera to measure hottest (weakest points) - vibration test - what fails first when it’s subjected to shaking and moving. - signal integrity tests - measure high speed circuits 3. Engineering Validation tests (EVT) ✅ - detailed functional tests - power measurements - drop tests - fire safety - vibration tests - hot / cold ambient temperature test - thermal cycling - signal integrity tests - EMI measurements - pre-compliance testing (FCC, UL) 4. Design Validation tests (DVT) ✅ - detailed functional tests - parameter fluctuations / batch testing - formal compliance tests (FCC, UL, CE) - accelerated aging test - lifetime testing Do you have to wait until you build great looking production samples from assembly line? ⛔️Absolutely not! Start testing as early as possible Some tests might cost a lot to be done correctly. But it doesn’t mean you can’t hack an easy testbench. Here’s a rapid vibration platform we are using to test early prototypes of #electric #bike we are building for Terraglide tricycle. Before we invest in an industrial grade vibro platform, we use consumer platform to run preliminary tests! 💪 With AJProTech - IoT Product Development #consumerelectronics #electronics #EVT #DVT #Prototypes