When building software, you need to determine if your software works before you get into the semi- and full-fledged testing cycle.
This is the reason for smoke testing. You could think of it along the lines of turning on a new electronic device for the first time and making sure it works before the device overheats and catches fire. If it smokes when you turn on the device, there is a significant problem.
Smoke testing is a technology to gauge if your software’s primary functions are correct. The essence of smoke testing is simple: it allows testers to quickly identify any massive problems before wasting more time testing.
What Does Smoke Testing in software testing Really Mean?
The literal term comes from testing hardware services. Software testers would turn on a powered-up circuit board, and they would either encourage smoke or power consumption to check if a failure occurred.
If smoke occurred, then they knew they had a failure. The same concept can be applied to software; however, these same test objectives can also be applied to the hardware, memory, and functionality of the application, which supports and delivers regular use of the software.
To be clear, you are checking to make sure the application is stable for continued testing. That is, if the application cannot pass a smoke test and demonstrate basic functionality, it would, in some limited sense, not be applicable for advanced testing.
Why Smoke Testing Matters in Software Development?
Smoke testing is crucial for preserving build stability and saving time. Without smoke testing, QA teams could spend hours regression testing or performance testing a broken build.
All software development projects have time constraints, and your development team is under pressure to ship builds as quickly as they can. But if you push a broken build to your testers, it’s a waste of time for everyone on your QA team to test the broken build.
Smoke testing provides a solution to this problem. Smoke testing is a gatekeeper for quality assurance to block unstable builds from consuming any more of your testing resources.
What Smoke Tests in software testing Actually Check?
When teams discuss smoke tests in software, they’re talking about a type of scripted testing that outlines a predetermined list of critical test cases designed to verify key functionalities.
For example:
- Does the application load properly?
- Does the user get signed in and signed out?
- Do the main web pages or dashboards load?
- Do any major integrations – like payment gateways, APIs, etc. – work?
These tests test the most important workflows. If they do not pass, there is no point in continuing with testing.
When to Run a Smoke Test?
Smoke tests are regularly performed immediately after a new software build is deployed to a testing or staging environment. After the developers write the code and create a build, the QA teams run the smoke tests to ensure that the build is healthy.
If the smoke tests pass, then the build will progress to deeper testing such as regression testing, integration testing, or user acceptance testing (UAT).
In modern CI/CD scenarios, smoke tests, which are automated, are run every time that there is a new build is deployed, meaning that no unstable code will ever reach production.
What is the Core Purpose Behind Smoke Testing in software testing?
All testing methodology has a specific purpose, and the purpose of smoke testing is simple: Is this build stable enough to undergo further testing?
The overall premise is defect detection at the earliest possible production phase; if you identify major issues within a build, developers have the opportunity to fix them before continuing to work on the build and others.
Smoke testing also limits the risk of producing broken software by discovering showstopper bugs at the earliest phase possible.
What are the Types of Smoke Testing Approaches?
Software teams utilize a variety of methodologies according to their needs, and part of being a good software engineer is knowing the different types of smoke testing, and how this knowledge may influence your choice of approach in your project.
1. Manual Smoke Testing
Manual smoke testing is performed when testers run test cases manually. A tester opens the application and checks the critical functions manually. This has the benefit of human observation and intuition.
2. Automated Smoke Testing
Automated smoke tests are run completely without manual execution. You write a set of tests once, and then you can run it without being in control of the action each time you need to verify the build. This is the most efficient method of testing.
3. Hybrid Testing Methods
Some teams are blending manual and automated approaches. Hybrid smoke testing uses automation for repetitive checks while tracking human- judged areas of testing through manual testing.
When to Perform Smoke Tests in Your Workflow?
The timing of smoke tests in testing is critical. You want to maximize the value of running smoke tests at just the right times. Below are four key points in the software development lifecycle in which smoke tests add the greatest value.
After Integration Testing Stage
Integration testing verifies the codebase’s several parts work together. After this integration testing stage, smoke tests are there to ensure the integrated system behaves in a stable manner.
During Continuous Integration Pipelines
Modern development methodologies promote continuous integration to merge code frequently, and those methods have automated smoke tests run each time the developer commits a new bit of code.
Prior to the Expected System Testing Begins
In the planned testing strategy, system testing is planned to evaluate a complete application to deep levels of testing. Before any effort is invested in the system testing phase, run smoke tests to ensure the application is behaving in a stable manner before spending time based on a very inaccurate build.
Prior to User Acceptance Testing Scheduled to Occur
User acceptance testing expects end-users to validate the software. Prior to users spending their time validating software, smoke tests should have been run in order to communicate that the application is expected to work as designed.
What is the Complete Smoke Testing process?
Smoke testing is an effective process that follows a systematic approach. Learning the process enables you to systematically smoke test within your organization. Below are the five steps for Smoke testing process:
Identifying Critical Test Cases
To begin, review your application so you can identify critical test cases. Critical test cases are scenarios that must work in order for your software to be usable. You should prioritize core workflows that users need most.
Prioritizing Your Test Suite
Not all critical test cases have the same degree of importance. It is important to prioritize these cases to ensure the most important functions have been tested first.
Executing Tests Efficiently
Run a priority test against all new builds. This part is very important. The faster you can get through smoke tests, the sooner developers will receive problems.
Analyzing Test Results Carefully
Once the tests have been run, analyze the results. Determine which test cases failed and where problems may have existed. Problems discovered in the failed test case could indicate a larger issue that needed to be addressed immediately.
Reporting Defects Clearly
In all smoke testing, it is necessary to document all defects identified and describe defects in detail, clearly explaining the steps to reproduce the defect or provide screenshots, log files, etc.
Building an Effective Smoke Test Suite
- To begin with, your smoke test suite is the set of all the test cases that you run to perform any smoke testing. Moreover, creating an effective smoke test suite takes thoughtful planning and ongoing management.
- Initially, start with a small set of absolutely essential test cases. Subsequently, as your application grows, and your smoke test suite needs additional test cases to cover new essential features/behaviour/changes, add to it gradually and only as needed.
- Furthermore, focus the smoke test suite on testing core functionality rather than problematic behaviour or test cases on the edge of passing/failing.
- Importantly, you need to find a balance. On one hand, a smoke test suite that is too small will inevitably miss important problems. On the other hand, a suite that is too large will take too long to execute losing the quick feedback purpose of smoke tests altogether.
- In practice, most effective teams try to keep their smoke test suite executable in 15-30 minutes, depending on the number and complexity of the overall tests.
Automated Smoke Tests: Best Practices and Tools
Automation changes smoke testing from a choke point to a positive point. Automated smoke tests run all the time, every time, without human labour. Here are a few best practices that are followed:
Popular Automation Tools
There are several automation tools that lend themselves to smoke testing. Selenium is the most common tool for web app testing. Appium allows you to write your tests once and run them on both Android and iOS platforms.
Maintaining Automated Tests
Automated tests need regular maintenance. When the features for an application change, the test cases should be updated as applicable. If you do not maintain tests, you risk false failures by spending time investigating things that are not issues.
Plan for some regularly scheduled suite reviews. Remove tests that are no longer relevant. Create or update smoke tests that reflect the current application behavior.
Overcoming Common Automation Challenges
There are challenges that come with automation. If you have brittle tests and minor UI changes cause them to fail, it is frustrating for teams. If possible, implement patterns (e.g., page object model) that insulate tests from changes in UI.
As your test suite matures, execution speed can become an issue. If you have a giant test suite running, try to run in parallel and see if any tests can be removed.
How can you measure the effectiveness of the Smoke Testing process?
You can’t improve what you can’t measure. You should have a baseline of measurements to understand how effective smoke testing is for your team.
Time to Execute Tests
Time your smoke test suite to measure how long it takes to run. In general, faster execution means faster feedback, but you must consider execution time against adequate coverage of core functionality.
If your tests are taking a long time, determine your bottlenecks. Can some tests run in parallel? Are there tests checking redundant features or conditions? Optimizing your execution time will make smoke testing a more feasible solution for more frequent use.
Defects Found Over Time
In each build, track how many defects your smoke testing is finding. More defects may mean that the quality of the build is decreasing, or it may mean that the smoke tests are working well.
Examine trends over multiple builds. What does this suggest about the quality? This data can help your development team understand how changes are affecting stability.
Test Coverage Numbers
What percentage of critical functionality is covered by your smoke tests? More coverage usually means more thorough testing, but this often comes at the cost of longer execution time.
Most teams strive to integrate testing all critical paths while keeping the tests as quick as possible. This again is subjective, since every team has a different idea of what exactly should test as critical.
Pass Rate Analysis
On each build, what is the percentage of smoke tests that pass? A high percentage means that the build is stable enough to conduct further testing. If you see a sudden dip in some tests passing, be sure to investigate. Most often this is a telltale sign that one code change has broken several different features.
Smoke Testing vs Sanity Testing
It is seen that Smoke Testing and Sanity Testing are often mistaken for one another. Although they sound similar, they fulfill different needs.
- Smoke Testing is broad and shallow. It verifies that major functionalities operate normally before performing in-depth testing to check whether the build is stable enough to conduct formal testing.
- Sanity Testing is narrow and deep. It verifies that a specific bug has been correctly fixed, or that a new functionality has been implemented correctly.
To put it simply: “Smoke testing asks, ‘Does this build meet the minimal tests to be declared stable enough for testing?” While sanity testing asks, “Are these changes working as expected?”
Smoke Testing vs Regression Testing
Another area of confusion is smoke testing vs regression testing.
Smoke tests confirm if the software build is fundamentally stable at a high level. However, regression testing tests, assumes the build to be stable and checks, modifies previously completed tests to confirm that new code changes do not affect existing functionality.
A smoke test, on the other hand, can take only a few minutes to complete and acts like a gate. If the build does not pass the smoke test, it does not proceed to regression testing.
Understanding a UAT Smoke Test
A UAT smoke test takes place at the beginning of the User Acceptance Testing (UAT) process. Before any testing is completed by clients or end users, Quality Assurance (QA) teams execute a short smoke test of the UAT environment.
The tests confirm that the build is stable enough to engage with client end-users. There is no reason to have a client testing a web application if they cannot even login or load the key dashboards.
These were just a couple of examples of how smoke testing focuses on limited core features instead of extensive test coverage.
Key Metrics to Track
To assess effectiveness, valuable smoke testing involves a few simple metrics:
- Execution Time: How long does it take to run the entire smoke test? The shorter, the better.
- Pass/Fail Rate: How many builds successfully pass smoke tests? If there’s frequent failure, one can assume there is an ongoing stability issue.
- Defects Found: How many critical defects do you find and report during the smoke test?
- Coverage of Core Features: Are your most important workflows being tested?
These metrics allow QA leaders to assess smoke testing value and continue improving their processes.
The Challenges of Smoke Testing
Although smoke testing is simple, it’s not without its methodical issues. Since the scope covers critical workflows only, there may be bugs lurking in secondary workflows.
Selecting which widgets fall under “critical” also tends to be subjective, as each tester may put a priority on several different workflows. Smoke testing is assurance that the flow is stable enough to continue testing.
5 Best Practices for Effective Smoke Testing
In order to get the full benefits of smoke testing, you should follow a few best practices:
- Keep your smoke test suite small but meaningful, only focusing on the workflows that really matter for your product’s success.
- Automate when you can. Automation guarantees reliability and efficiency, which is particularly important in CI/CD pipelines.
- Keep your smoke tests up to date with new or modified core features.
- If smoke tests fail, first fix the build before proceeding further.
- Run smoke tests in an environment that most closely resembles production so that you can capture issues early.
By adhering to these best practices, you will ensure your smoke testing remains relevant, focused, and productive in advancing your development goals.
Final Word
In a nutshell, smoke testing is an incredibly valuable element of your software quality toolbox for identifying fundamental issues quickly for early feedback and an efficient use of resources.
Smoke testing guarantees that you establish robustness in each build, create stronger software development processes, and maintain your developer workflow health in CI/CD pipelines.
In SaaS and agile teams, smoke tests should be automated and offer a ton of value in terms of faster releases, higher quality, and fewer surprises at the last second before release.
Frequently Asked Questions
Q1. What is the difference between UAT and smoke test?
A UAT (User Acceptance Test) focuses on validating that the software meets business requirements and is ready for production from an end-user perspective.
Q2. What is a UAT smoke test?
A UAT smoke test is a preliminary check performed before formal user acceptance testing begins. It ensures that the application is accessible, stable, and that major workflows are functioning so users can proceed with full UAT without interruptions.
Q3. Is smoke testing part of Agile?
Yes, smoke testing is an integral part of Agile. It is performed after every build or deployment to quickly verify system stability before further testing or integration. In Agile environments, where builds are frequent, smoke tests help maintain quality and detect issues early.
Q4. What is smoke testing with example?
Smoke testing is the process of running a basic set of tests to ensure the main features of an application work as expected.
Example:
After a new build of an e-commerce website, a smoke test might verify that:
- The website loads successfully
- Users can log in
Products display correctly - The “Add to Cart” and “Checkout” buttons work
If any of these fail, the build is rejected and sent back for fixes before deeper testing begins.
