Cisco 200-901 Exam Dumps & Practice Test Questions

Question 1:

Which two statements accurately reflect key principles of test-driven development (TDD)? (Choose two.)

A User acceptance testers are responsible for defining the test cases.
B It supports and facilitates the process of code refactoring.
C Testing is initiated only when the code is ready for deployment.
D Development progresses through repeated testing of near-final builds.
E Tests are designed and written prior to coding implementation.

Correct Answer: B, E

Explanation:

Test-Driven Development (TDD) is a disciplined software development methodology that places testing at the forefront of the development cycle. Rather than writing code first and testing later, TDD begins with the creation of test cases that define how the software should behave. Only once these tests are in place does the developer begin writing the functional code needed to satisfy them.

Option B, which states that TDD enables code refactoring, is correct. One of the major advantages of TDD is the confidence it gives developers to refactor code. Because the test suite acts as a safety net, developers can modify and optimize existing code, knowing that the tests will immediately highlight any regressions or unintended side effects. This leads to cleaner, more maintainable software over time.

Option E is also correct because writing tests before writing the actual code is the defining feature of TDD. The process follows a "Red-Green-Refactor" cycle: first, a failing test is written (Red), then code is added to make the test pass (Green), and finally, the code is refined or refactored (Refactor) without altering its functionality. This ensures high test coverage and minimal bugs.

Option A is incorrect because in TDD, developers themselves write the unit tests—not user acceptance testers. User Acceptance Testing (UAT) comes later in the software lifecycle and is distinct from the developer-driven TDD approach.

Option C misrepresents the TDD timeline. Waiting until code is ready for release to write tests goes against the TDD philosophy of early and continuous testing.

Option D incorrectly describes development as being driven by release candidate testing. TDD focuses on incremental development and testing during the coding process—not at the release stage.

In summary, the two core concepts of TDD are writing tests before the implementation (E) and enabling safe refactoring (B), both of which contribute to robust and reliable software.

Question 2:

Which task aligns with the principles of test-driven development (TDD)?

A Designing test cases based on ongoing development work
B Writing functional code with zero style violations
C Refactoring code that has corresponding unit tests
D Validating existing code prior to introducing new functionality

Correct Answer: C

Explanation:

Test-Driven Development (TDD) revolves around the idea of writing automated tests before any functional code is implemented. The process involves small, incremental steps that start with a failing test, followed by writing the minimal code necessary to pass that test, and finally refactoring the code to improve its structure without changing its behavior. TDD is highly effective in promoting high-quality, maintainable software.

Option C, which states that developers refactor code covered by existing tests, accurately represents a central practice of TDD. After a developer writes tests and gets the initial implementation to pass, the code is typically revisited for optimization, cleanup, or restructuring. This refactoring step is safe to perform because the pre-existing tests provide immediate feedback, helping ensure that any changes do not break the intended behavior. It supports continuous improvement of the codebase without compromising reliability.

Option A is partially related to TDD but doesn’t capture its essence. In TDD, test cases are created before development, not in response to it. The phrase "based on continuous development" implies a more reactive approach, which deviates from TDD’s proactive, test-first method.

Option B refers to maintaining code quality and avoiding violations of coding standards, which is always encouraged but not unique to TDD. Adherence to style guidelines is important, but it doesn’t reflect the iterative test-write-refactor cycle that defines TDD.

Option D suggests testing legacy or pre-existing software before adding new features. This approach is more aligned with traditional testing or integration testing and doesn’t reflect the TDD practice of writing tests for new functionality before implementation.

In conclusion, the correct answer is C because TDD encourages frequent code refactoring, which is made safer and more effective by the existence of robust, automated tests that validate behavior after each change. This continuous feedback loop fosters better design, fewer bugs, and more maintainable software.

Question 3:

When following a test-driven development (TDD) approach, what is the initial task a developer should perform?

A Write the code that performs the desired functionality
B Create a test that is expected to fail for the new feature
C Deconstruct the current codebase to identify how the function works
D Write a test that passes based on existing logic

Correct Answer: B

Explanation:

In the test-driven development (TDD) methodology, the very first action a developer takes is to write a failing test that defines the desired functionality. This foundational concept ensures that development is driven by requirements and that no unnecessary code is written. This stage is often referred to as the "Red" phase in the TDD cycle — Red, Green, Refactor.

By writing a failing test first, developers clarify what the system should do. The test reflects the expected behavior of the feature or function before any implementation takes place. This also acts as a safety net — if the code doesn’t make the test pass, then it’s clear that the implementation isn’t correct or complete.

The typical TDD workflow follows three phases:

1. Red: Write a unit test that targets the desired behavior. Since the implementation doesn’t exist yet, the test will naturally fail.

2. Green: Write the minimum amount of code necessary to pass the test. This code may not be optimal, but it should meet the expectations defined in the test.

3. Refactor: Clean up the code to improve structure, readability, and performance — while ensuring the test still passes.
   
   

Let’s consider why the other choices are incorrect:

• A suggests writing the functional code first, which contradicts the TDD cycle — code should only follow a failing test.

• C refers to reverse engineering, which is not relevant in TDD, where new features are being proactively built.

• D implies testing existing code, but TDD involves writing tests before the code exists, and the test should fail first to drive development.

Therefore, the correct first step in TDD is writing a failing test to define what the feature should do, making B the right answer.

Question 4:

In the context of test-driven development, which two techniques are considered green bar patterns? (Choose two)

A another test
B break
C triangulate
D starter test
E fake it

Correct Answers: C, E

Explanation:

In test-driven development (TDD), the term "green bar" refers to a test that passes successfully — many testing frameworks show a green indicator when this occurs. Green bar patterns are development tactics used to quickly get to a passing (green) state after writing a failing test.

Two commonly used green bar strategies are triangulate and fake it:

• C (triangulate): This pattern involves writing several tests that cover various cases of a problem. Each test adds a new dimension, pushing the developer to generalize the implementation. It’s especially useful when solving mathematical or logical problems. By triangulating, the developer avoids hardcoding solutions and is forced to find patterns or rules that satisfy all tests — leading to more robust, flexible code.

• E (fake it): The fake it approach is about writing the simplest code possible just to pass the test. For instance, if a test expects a function to return 5, you could hardcode return 5. While this isn’t scalable, it helps achieve a passing test quickly. The solution is then gradually improved during the refactor phase. This pattern aligns with TDD's focus on incremental progress.

Let’s explore why the other choices don’t fit:

• A (another test): While adding tests is part of TDD, this isn’t a green bar pattern. Green bar patterns are focused on how to pass the current test, not on creating more tests.

• B (break): Introducing failure intentionally can help verify that a test catches errors, but it’s not used to reach a green bar.

• D (starter test): A starter test is often used at the beginning of a TDD cycle, but it doesn’t represent a technique to reach a green state — it’s more about initiating the process.

In summary, triangulate and fake it are effective TDD strategies for reaching a passing test quickly, which makes C and E the correct answers.

Question 5:

In a test-driven development process, what is typically updated after a test fails?

A. Schedule
B. Project requirements
C. Code
D. Test

Correct Answer: C

Explanation:

Test-Driven Development (TDD) is a software development approach where writing tests comes before writing the actual code. It follows a disciplined cycle: first, the developer writes a test based on a specific requirement; second, they run the test, which will fail since the corresponding code does not yet exist; third, they write just enough code to make the test pass; and finally, they refactor the code for better quality while ensuring it still passes the test.

When a test fails during this cycle, it means that the current code does not fulfill the required functionality. Therefore, the code is what gets changed to make the test pass. This feedback loop of writing a test, seeing it fail, and then writing the code needed to make it succeed is the foundation of TDD.

Let’s examine why the other choices are incorrect:

• A (Schedule): While failed tests could potentially delay progress, the project schedule is not something that changes directly as a response to a test failure in TDD. The focus is on improving the code, not altering timelines.

• B (Project requirements): Requirements come from stakeholders and remain stable unless formally changed. A test failure indicates that the current implementation doesn't meet these requirements—not that the requirements themselves are incorrect or should be changed.

• D (Test): In TDD, the test should remain unchanged after a failure. It serves as the benchmark for correct functionality. The developer’s goal is to change the code until it passes the test, not to adjust the test to accommodate flawed code.

In summary, a failed test in TDD highlights a shortcoming in the implementation. The proper response is to update the code so that it satisfies the predefined test case. This method helps developers build functionality incrementally while ensuring high confidence in the software’s correctness. Thus, the correct answer is C.

Question 6:

Which of the following is a key advantage of using test-driven development?

A. Ensures complete alignment with product requirements
B. Enables faster releases with fewer features
C. Encourages early customer feedback
D. Improves the quality of the code

Correct Answer: D

Explanation:

Test-Driven Development (TDD) is a disciplined programming method that improves software design and reliability by requiring developers to write test cases before developing actual application code. The cycle involves writing a test for a specific feature, allowing it to fail, coding the feature to pass the test, and finally refactoring the code while maintaining test success. This process results in more intentional, cleaner code.

The most significant benefit of TDD is that it increases code quality. Here’s how:

• Preemptive Problem Detection: Since tests are written first, developers must consider expected behavior and edge cases early. This proactive thinking results in code that is more resilient and less prone to defects.

• Safe Refactoring: With a comprehensive suite of tests in place, developers can refactor confidently, knowing any regression or unintended consequence will be quickly caught.

• Better Design: TDD naturally encourages modular and loosely coupled code, making systems easier to maintain and extend.

• Living Documentation: The test suite also acts as real-time documentation of how the system should behave, which is useful for both current and future team members.

Now let’s evaluate the other options:

• A (Strict adherence to product requirements): While TDD can help ensure functionality aligns with expectations, adherence to requirements is primarily achieved through requirements gathering and validation—not solely through test-first coding.

• B (Faster releases with minimal features): TDD may initially slow down development due to the extra step of writing tests first. Over time, it pays off through better maintainability, but it doesn’t inherently result in faster releases.

• C (Early customer involvement): Although TDD supports early validation, it doesn’t directly include customers in the process. Agile methodologies and iterative feedback loops are better suited for involving customers early.

Therefore, the most accurate and relevant benefit of TDD is its strong contribution to improved code quality, making D the correct answer.

Question 7:

Which two benefits accurately describe the value of using a version control system in a development environment? (Choose two.)

A. It allows independent development using branching and later integration through merging.
B. It enables automated builds and provisioning of infrastructure.
C. It lets multiple developers work on the same files and helps manage their changes.
D. It is used to manage User Stories and assign tasks to development backlogs.
E. It improves the process of writing unit tests for code validation.

Correct Answer: B, C

Explanation:

A version control system (VCS) is an essential tool in modern software development that helps teams manage and track changes to code, configuration files, and documentation. Its main function is to support collaboration by maintaining a complete history of modifications and offering mechanisms for conflict resolution, branching, and merging.

One major advantage of using a VCS is the ability to create branches for new features, bug fixes, or experiments (Option A). This allows developers to work in isolated environments without impacting the main project codebase. Once development in a branch is complete and tested, the changes can be merged into the main branch. This feature streamlines collaboration and facilitates the development of multiple features in parallel.

Another core advantage is that a VCS helps multiple developers work on the same codebase by identifying and managing conflicts between their contributions (Option C). When two team members make changes to the same file, the VCS detects overlapping changes and helps users resolve the conflicts through merging tools. This coordination is critical in team-based development environments.

Other options do not accurately represent core VCS capabilities. For instance, Option B refers to automation of builds and infrastructure provisioning, which is typically handled by CI/CD tools like Jenkins, GitHub Actions, or Terraform, not by version control systems directly.
Option D, managing User Stories or task allocation, is a function performed by project management tools such as Jira or Trello, not by a VCS.
Option E suggests that a VCS contributes to writing unit tests, but in reality, while a VCS may store unit test files, the responsibility for writing and maintaining them lies with developers.

In summary, the true advantages of a version control system are enabling branching and merging (A) and supporting collaboration through conflict management (C), which makes them the correct answers.

Question 8:

Which two choices reflect important advantages of using version control software? (Choose two.)

A. It enables tracking and comparison of changes in binary files.
B. It gives new developers access to the current project code and its entire history.
C. It supports reviewing differences between various code revisions.
D. It provides wiki collaboration for team documentation.
E. It facilitates hosting of previous application builds on the web.

Correct Answer: B, C

Explanation:

Version control software plays a critical role in software engineering by enabling teams to effectively manage, track, and collaborate on code. Two of its most important features include providing access to code history and supporting revision comparison.

First, version control systems allow new team members to access both the current codebase and its full historical context (Option B). When someone joins a team, they can instantly view the latest source code and explore previous changes, including who made them, when, and why. This transparency helps in understanding the rationale behind architectural or design decisions and accelerates onboarding. It also aids in tracing the origin of bugs or regressions.

Another vital feature is the ability to compare changes across different file versions (Option C). This comparison helps developers conduct code reviews, identify bugs, and understand the impact of specific changes. Version control tools like Git highlight line-by-line differences, making it easier to assess modifications between commits or branches. This capability is particularly helpful when troubleshooting or performing audits.

As for Option A, while some VCS tools can technically track changes in binary files (e.g., images, PDFs), they don't provide meaningful diff outputs because these files are not human-readable. Thus, their support for binary files is limited and not a primary advantage.

Option D refers to wikis, which are sometimes included in VCS platforms like GitHub or GitLab. However, these are add-ons rather than core VCS features. The primary role of version control is not to facilitate team documentation but to manage source code.

Finally, Option E misrepresents a version control system’s purpose. Although developers can revert to old versions of code, VCS tools are not designed to host or distribute application builds. That functionality falls under the responsibility of artifact repositories (e.g., Nexus, Artifactory) or hosting platforms.

Therefore, the most accurate and core advantages of version control software are B and C: enabling access to code history and supporting file revision comparisons.

Question 9:

At which stage in the version control workflow is code typically reviewed before it becomes part of the project's history?
A. When checking out the code
B. During code merging
C. Before committing changes
D. While creating a new branch

Correct Answer: C

Explanation:

Code review plays a vital role in maintaining software quality and ensuring adherence to best practices. In a version control environment, such as Git, the review process usually occurs before the code is committed to the local repository. This allows for an extra layer of scrutiny to identify bugs, enforce coding standards, and improve overall code readability before the changes become part of the codebase.

Let’s explore the choices:

• A. Checkout of code: This refers to pulling or downloading code from the repository to a local workspace. Code review is not associated with this phase, as it involves no new code creation or changes requiring assessment.

• B. Merge of code: Merging is the act of integrating code from one branch into another, typically from a feature branch into the main or development branch. Although some reviews may occur at this point—especially in pull requests—it's ideal and common to review code before the commit to catch issues early and reduce the complexity of merges.

• C. Committing code: This is the correct answer. Developers typically initiate a review process after writing code but before committing it. By doing so, reviewers can assess changes, request modifications, and ensure code quality before the commit logs it in the repository's history.

• D. Branching code: This involves creating a new branch from the main codebase, often for developing a feature or fixing a bug. No code changes exist yet during branching, making code review at this point unnecessary.

To summarize, the code review process is designed to verify code quality and consistency before it becomes a permanent part of the version control system. Hence, it is generally done prior to committing changes, which makes C the best answer.

Question 10:

What is a key benefit provided by using a version control system in collaborative software development?

A. Helps resolve merge conflicts between different developers’ code
B. Ensures unit tests are included in every change
C. Blocks overwriting of configuration files automatically
D. Enforces trunk-based development methodology

Correct Answer: A

Explanation:

A version control system (VCS) is an indispensable tool in modern software development, especially when teams are collaborating on large projects. One of its major benefits is facilitating conflict resolution during code merges. When multiple developers make changes to a shared codebase—often in different branches—a VCS helps merge those changes intelligently and flag any conflicts for resolution.

Let’s break down the choices:

• A. Facilitates resolving conflicts when merging code: This is correct. A robust VCS like Git identifies when multiple changes affect the same lines or files and brings those conflicts to the developer’s attention. This built-in mechanism allows team members to manually or automatically resolve discrepancies, ensuring code integrity. This feature is particularly crucial in collaborative environments with parallel development efforts.

• B. Ensures that unit tests are written: This is incorrect. Although writing unit tests is a best practice, it is not enforced by the VCS itself. Developers must adopt testing strategies independently or through automated CI/CD tools, which can trigger test requirements, but the VCS has no authority over testing practices.

• C. Prevents overwriting code or configuration files: This is partially true but misleading. While version control helps track and revert changes, it doesn't outright prevent overwrites. Instead, it offers tools to compare changes, create branches, and restore previous versions, thereby mitigating the risks associated with overwrites.

• D. Forces the practice of trunk-based development: This is false. A VCS is flexible and does not impose any specific development methodology. While it supports trunk-based development, it also accommodates branching, feature-based workflows, and GitFlow, leaving the choice of strategy to the development team.

In essence, one of the standout advantages of using a version control system is how effectively it manages merge conflicts, promoting smooth collaboration. That makes A the most accurate answer.