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Manual vs Automated Testing: Understanding the Strengths, Limitations, and Use Cases of Each Quality Assurance Approach

Auteur n°3 – Benjamin

By Benjamin Massa
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Summary – Software quality underpins user trust and organizational agility, making the choice between manual and automated testing strategic for optimizing cost, coverage and UX. Manual testing brings user empathy, exploratory flexibility and visual anomaly detection, while automation ensures speed, reproducibility, CI/CD feedback and ROI on critical workflows.
Solution: deploy a hybrid QA strategy built on modular open-source tools integrated into CI/CD pipelines, complemented by clear governance and team upskilling to balance exploratory innovation with technical robustness.

In a context where software quality underpins user trust and organizational agility, distinguishing manual testing from automated testing is a strategic necessity. Each approach has its advantages: manual testing excels in creativity and user empathy, while automation delivers speed and reproducibility at scale. Understanding their strengths, limitations, and respective applications enables you to build a coherent and cost-effective Quality Assurance strategy aligned with your business objectives, resources, and performance requirements.

Fundamentals of Manual and Automated Testing

Manual testing relies on intuition, experience, and the human eye to capture unforeseen scenarios. Automated testing uses reproducible scripts and tools to validate functional and technical workflows quickly.

Nature and Objectives of Manual Testing

Manual tests are executed step by step by one or more testers who interact directly with the application, reproducing various user journeys. They allow the evaluation of visual consistency, navigation ease, and functional clarity of the interface. With each new release, a tester can identify subtle anomalies, unexpected behaviors, or usability issues.

This approach is particularly suited to detecting qualitative defects—such as misplaced text, inappropriate color choices, or poorly worded error messages. It offers the flexibility to develop or adjust scenarios in real time based on ongoing findings. In this sense, it reflects the true perception of an end user.

However, it is time-consuming to cover all features consistently and difficult to reproduce identically across multiple cycles. Each tester may interpret the same scenario differently, potentially undermining the reliability of functional coverage. Therefore, manual testing is often associated with specific or exploratory test cases rather than large-scale repetitive validations.

Principles and Tools of Automated Testing

Automated tests use scripts—written in various programming languages—to execute predefined sets of checks like smoke tests without human intervention. They aim to systematically validate key flows, such as login, cart management, or transaction processing, and to detect regressions with each release.

With open-source frameworks like Selenium, Cypress, or JUnit, these tests can be integrated into Continuous Integration/Continuous Deployment (CI/CD) pipelines to run on every commit. The result: rapid feedback on code changes, immediate alerts in case of failures, and reliable documentation of the current software quality.

Nevertheless, automation requires an initial investment in time and expertise to write, maintain, and adapt scripts. Complex scripts can become brittle in the face of frequent UI changes, requiring refactoring efforts. Some scenarios—particularly those related to user experience—remain beyond the scope of full automation.

Impact on Costs, Reliability, UX and Performance

The choice between manual and automated testing directly affects your budget, regression risks, and user satisfaction. An informed decision optimizes the balance between operational costs and delivered quality.

Costs and Return on Investment

Manual testing requires qualified human resources and longer timeframes to cover a broad scope. Each testing iteration can represent several person-days, with costs proportional to the level of detail required. In projects with high release frequency, this approach can quickly become expensive and slow down deliveries.

Automation, by contrast, entails an initial effort to develop scripts and set up the infrastructure (tools, test environment). Once in place, automated scenarios can be replicated with minimal additional cost, generating a favorable return on investment (ROI) from the third or fourth execution onwards. In long-term or mission-critical projects, this investment translates into a notable reduction in testing cycles and regression risks.

However, it is essential to assess the complexity of the scope to cover: automating all scenarios of a large-scale system may exceed the initial budget if the tests are too granular or unstable. A careful trade-off is necessary to target automation efforts where they deliver the most value.

Reliability and Test Coverage

With manual testing, coverage depends on the tester’s thoroughness and scenario repeatability. If documentation and procedures are not strictly formalized, critical paths may be overlooked between cycles, exposing the application to hidden regressions. Moreover, human subjectivity can lead to divergent interpretations of the same expected result.

Automated tests, in turn, guarantee identical execution each time. They precisely document the steps taken, data used, and outcomes obtained, enhancing traceability and confidence in the deliverable’s quality. Alert thresholds and detailed reports contribute to better visibility of risk areas and facilitate decision-making.

However, scripted tests are limited to the cases defined during development: any unexpected scenario or visual defect will not be detected. That is why complementary exploratory manual testing remains indispensable to ensure comprehensive coverage.

Impact on User Experience

Customer experience is not measured solely by technical performance: it also includes the smoothness of the user journey, visual consistency, and functional clarity. Manual testing, by navigating the application like an end user, identifies friction points and potential misunderstandings, ensuring an intuitive and enjoyable interface.

Automated tests, for their part, verify the robustness of features under varying loads and ensure the stability of critical mechanisms (payment, authentication, collaborative workflows). They prevent technical regressions that could degrade performance or cause production incidents, thereby maintaining user trust.

Therefore, a balance must be struck: optimize UX through human feedback and secure technical integrity with reproducible scripts to deliver a product that is both efficient and pleasing.

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Concrete Use Cases: When to Prioritize Each Approach

Every project requires a unique blend of manual and automated testing based on its size, criticality, and technological maturity. Specific use cases determine the strategy to adopt.

Exploratory Testing and UX/UI Validation

During prototyping or interface redesign phases, manual exploratory tests capture testers’ spontaneous reactions to new features. These qualitative insights reveal design and journey adjustment opportunities, anticipating potential frustrations for end users.

A guided testing protocol with open-ended objectives and evolving scenarios encourages the discovery of undocumented anomalies and feeds the product roadmap. This agile approach fosters innovation and differentiation by integrating early feedback from initial users.

In low-code or no-code environments, where interfaces change rapidly, manual testing remains the most suitable method to validate ergonomics and ensure design consistency before automating stabilized scenarios.

Regression, Performance and Load Testing

A Swiss public organization recently faced an unexpected surge of users on its online management platform. To validate scalability, it deployed automated test scripts simulating thousands of concurrent connections, quickly identifying bottlenecks and adjusting server configuration.

This case demonstrates the power of automation to assess system resilience under stress and ensure service continuity. Teams iterated on infrastructure and database parameters by re-running the same scenarios without repeated human effort.

Automated regression tests also ensure that no code changes introduce critical regressions, which is particularly valuable in projects with short delivery cycles and microservices architectures.

Hybrid Quality Assurance Strategy for Complex Projects

For a large-scale digitalization project combining open-source components and custom developments, a hybrid Quality Assurance approach balances manual testing for exploratory coverage and automation for repetitive scenarios. Each critical feature is covered by an automated script, while manual sessions are scheduled each sprint for cross-functional workflows.

This modular approach prevents inflating the automated script base with edge cases, while maintaining constant assurance of core flows. It promotes the upskilling of internal teams, which contribute to script writing and manual test planning.

Ultimately, the hybrid strategy ensures both agility and robustness by leveraging the strengths of each method.

Selecting and Integrating Tools for Effective Quality Assurance

Modular open-source tools integrated into CI/CD pipelines are the key to scalable and sustainable Quality Assurance. Proper governance and internal training ensure a controlled deployment.

Favor Modular Open-Source Solutions

A Swiss fintech firm, aiming to avoid vendor lock-in, adopted an open-source automation framework for its functional and performance tests. With a modular architecture, the QA team developed reusable function libraries and shared test components across multiple projects.

This choice demonstrates the flexibility offered by open source, allowing scripts to be adapted as APIs and business layers evolve, without reliance on proprietary vendors. The community and regular updates ensure a solid and secure foundation.

The modular approach also facilitates integrating tests into a DevOps pipeline by providing plugins and connectors for most orchestration and reporting solutions.

Integration into CI/CD and DevOps Pipelines

Integrating automated tests into a CI/CD pipeline ensures that every pull request is validated through unit, integration, and end-to-end test suites before merging. This automation eliminates friction by delivering immediate feedback on code health.

Open-source orchestrators like GitLab CI, Jenkins, or GitHub Actions enable parallel execution, coverage reporting, and automatic alerts on failures. Centralized logging and screenshots streamline incident analysis.

Combined with ephemeral environments (containers, on-demand test environments), this CI/CD integration guarantees test isolation and full reproducibility of execution conditions.

QA Governance and Skill Development

Successful Quality Assurance requires clear governance: defining responsibilities, identifying critical scenarios, and establishing performance metrics (coverage rate, average bug detection time, regression rate). These metrics drive QA strategy evolution.

Continuous training for internal and external teams strengthens mastery of tools, best practices, and DevOps concepts. Regular workshops foster knowledge sharing among testers, developers, and system administrators.

This governance creates a virtuous cycle: improved expertise enhances the quality of scripts and manual sessions, which generate more relevant feedback and reinforce confidence in the overall delivery process.

Optimize Your QA Strategy with a Hybrid Approach

Manual and automated testing are complementary facets of modern Quality Assurance. The former ensures user sensitivity and exploratory flexibility, while the latter provides speed, reliability, and traceability at scale. A hybrid strategy, integrated into a CI/CD pipeline and built on modular open-source tools, strikes the right balance between cost, performance, and quality.

Our experts at Edana support CIOs, CTOs, and Executive Boards in defining and implementing this context-driven, secure, and scalable strategy. We tailor every approach to your business challenges, prioritizing open source, modularity, and team skill development.

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By Benjamin

Digital expert

PUBLISHED BY

Benjamin Massa

Benjamin is an senior strategy consultant with 360° skills and a strong mastery of the digital markets across various industries. He advises our clients on strategic and operational matters and elaborates powerful tailor made solutions allowing enterprises and organizations to achieve their goals. Building the digital leaders of tomorrow is his day-to-day job.

FAQ

Frequently Asked Questions on Manual and Automated Testing

How do you determine the optimal balance between manual and automated testing in an enterprise project?

To find the right mix of manual and automated tests, analyze the project context: release frequency, process criticality, and technology maturity. Automate high-value repetitive scenarios (regression, performance) and reserve manual testing for exploratory flows, UX, and exceptional cases. Establish balance through an initial audit, use-case prioritization, and periodic reviews to optimize cost and quality coverage.

What are the initial and recurring costs associated with implementing automated testing?

Automated testing requires an upfront investment in time and skills (tool selection, script writing, CI/CD setup). With open-source tools, software costs remain low, but script maintenance and scenario updates demand ongoing effort. Manual tests consume human resources and validation time each cycle. ROI becomes favorable by the third run of automated tests in long-term projects.

How do you assess the reliability of manual and automated tests?

Measure reliability using indicators such as script functional coverage, critical bug detection rate, and execution repeatability. Automated tests provide detailed reports and logs for traceability and consistency. Manual tests require thorough documentation (scenarios, checklists) and cross-review sessions to reduce subjectivity. Periodic audits ensure coverage adapts to application changes.

What common mistakes should you avoid when implementing a hybrid QA strategy?

Common hybrid QA mistakes include trying to automate every scenario, even low-value or unstable ones, which complicates maintenance. Neglecting manual test documentation and end-user involvement can harm UX quality. Failing to prioritize critical flows risks major regressions. Finally, ignoring continuous team training on open-source tools and DevOps best practices can slow adoption and overall performance.

Which key indicators (KPIs) should you track to measure the effectiveness of automated tests?

Key KPIs for automated testing include script coverage of critical flows, average suite execution time, failure frequency (flaky tests), and average defect detection and fix time. Supplement these metrics with pre-production regression catch rate and release acceptance rate. These indicators guide QA strategy and help adjust testing priorities.

How much time should you plan for developing and maintaining an automated test suite?

Time to develop an automated test suite depends on scenario complexity and team maturity: a simple test can take a few days, while a full business workflow may require several weeks. The initial phase includes framework selection, script writing, and CI/CD configuration. Allocate time for script refactoring during functional updates and ongoing maintenance to ensure reliability.

When should you favor exploratory manual testing?

Exploratory manual testing is best during prototyping or UI/UX redesigns to capture spontaneous feedback and identify visual or ergonomic issues that cannot be scripted. It also fits low-code environments with rapidly evolving interfaces and for validating exceptional or customized flows. This approach provides an authentic user perspective, ensuring a smooth experience before stabilizing scenarios for potential automation.

How do you integrate automated tests into an existing CI/CD pipeline?

To integrate automated tests into an existing CI/CD pipeline, start by containerizing test environments (Docker, Kubernetes) and configuring runners (GitLab CI, Jenkins, GitHub Actions). Trigger unit, integration, and end-to-end suites on each pull request. Parallelize jobs, manage test data, and centralize reports for fast feedback. Use ephemeral environments to ensure reproducibility and isolate tests for reliable pre-deployment results.

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