Explanation / Rationale

According to the dependencies, SEARCH tests must be executed first, then VIEW tests, then ADD tests and, at the end, ORDER tests. Within each of these groups the order is determined by the priorities of the test cases.
So, TC1 must be executed first, then TC2, then TC4 followed by TC3, and then TC5 as the last one.
So, the ordering is: TC1, TC2, TC4, TC3, TC5.
Thus:
a) Is correct. TC3 will be the fourth test case executed
b) Is not correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. In all types of reviews there is more than one role, even in informal ones
b) Is correct. There are several activities during the formal review process
c) Is not correct. Documentation to be reviewed should be distributed as early as possible
d) Is not correct. Defects found during the review should be reported

Explanation / Rationale

a) Is not correct
b) Is not correct
c) Is not correct
d) Is correct. This rule holds for all SDLC models

Explanation / Rationale

a) Is not correct. The fundamental strength of white-box test techniques is that the entire software implementation is taken into account during testing
b) Is not correct. White-box coverage measures provide an objective measure of coverage and provide the necessary information to allow additional tests to be generated to increase this coverage
c) Is not correct. White-box test techniques can be used to perform reviews (static testing)
d) Is correct. This is the weakness of the white-box test techniques. They are not able to identify the missing implementation, because they are based solely on the test object structure, not on the requirements specification

Explanation / Rationale

a) Is correct. Debugging is the process of finding, analyzing, and removing the causes of failures in a component or system
b) Is not correct. Testing is the process concerned with planning, preparation and evaluation of a component or system and related work products to determine that they satisfy specified requirements, to demonstrate that they are fit for purpose and to detect defects. It is not related to fixing causes of failures
c) Is not correct. Requirement elicitation is the process of gathering, capturing, and consolidating requirements from available sources. It is not related to fixing causes of failures
d) Is not correct. Defect management is the process of recognizing, recording, classifying, investigating, resolving, and disposing of defects. It is not related to fixing causes of failures

Explanation / Rationale

a) Is not correct. Testing quadrants group test levels and test types separately according to several criteria. They do not represent any combinations of test levels and test types and they are not related to any location within a software development lifecycle. Both test levels and test types are treated separately in the testing quadrants model
b) Is not correct. Testing quadrants group test levels and test types according to several criteria. They do not describe the degree of granularity of individual test types performed at each test level. Such a model, regarding the test levels, is called the test pyramid
c) Is not correct. The statement is wrong, because in general any test type can be performed at any test level
d) Is correct. The testing quadrants group test levels, test types, activities, test techniques and work products in Agile software development. In this model, tests can be business facing or technology facing. Tests can support the team (i.e., guide the development) or critique the product (i.e., measure its behavior against expectations). The combination of these two viewpoints determines the four quadrants

Explanation / Rationale

a) Is not correct. Quality control applies to all development activities, meaning that every software development activity has a corresponding test activity. However, here we are attempting to equate test levels with development levels, and, although we know what is meant by ‘test levels’, there is no common understanding of the term ‘ development level’
b) Is not correct. Every software development activity has a corresponding test activity; however test objectives are quite different. For instance, there might be a test objective of ensuring that a test object adheres to a contractual requirement that a certain type of testing must be performed before delivery. In this case there is no reason for there to be a corresponding development objective
c) Is not correct. Quality control applies to all development activities, meaning that every software development activity has a corresponding test activity. However, the same symmetry does not apply to testing and user activities. For instance, for some systems it is difficult to even identify the end users. Also, some test activities are focused on developers (e.g., testing for ease of maintainability), which has no user aspect to it
d) Is correct. Quality control applies to all development activities, meaning that every software development activity has a corresponding test activity

Explanation / Rationale

a) Is not correct. Risk management consists of risk analysis and risk control. Neither of these activities supports the reassembly of the files that made up the release, because these activities deal with risks, not with configuration items
b) Is not correct. Test monitoring is concerned with gathering information about testing. This information is used to assess test progress and to measure whether the test exit criteria or the test tasks associated with the exit criteria are satisfied, such as meeting the targets for coverage of product risks, requirements, or other acceptance criteria. Test control uses the information from test monitoring to provide, in the form of control directives, guidance and the necessary corrective actions to achieve the most effective and efficient testing. None of these activities deal with the management of configuration items
c) Is not correct. The whole-team approach builds on the tester’s skill to work effectively in a team context and to contribute positively to the team goals. So, it focuses on team-related issues, not on configuration items
d) Is correct. Configuration management provides a discipline for identifying, controlling, and tracking work products. Configuration management keeps a record of changed configuration items when a new baseline is created. Using configuration management, it is possible to revert to a previous baseline in order to reproduce previous test results

Explanation / Rationale

a) Is correct. Defect management is no less expensive. Finding and fixing defects later in SDLC is more costly
b) Is not correct. This is a benefit of static testing
c) Is not correct. This is a benefit of static testing
d) Is not correct. This is a benefit of static testing

Explanation / Rationale

Considering each of the listed benefits and drawbacks of the independence of testing:

i. Ideally, we want close collaboration between testers and developers, which is not increased by isolation. Thus, this is a disadvantage
ii. Testers and developers have varied backgrounds, technical viewpoints, and potential biases, allowing testers to usefully challenge assumptions made by stakeholders during system specification and implementation. Thus, this is an advantage
iii. The main disadvantage of independence in testing is that testers may become isolated from the development team, leading to communication problems, a lack of collaboration, and potentially an adversarial relationship, with testers being blamed for delays and bottlenecks in the release process. Thus, this is a disadvantage
iv. One of the disadvantages of independence in testing is that testers may become isolated from the development team, leading to developers feeling less accountable for quality. Thus, this is a disadvantage
v. The primary benefit of independence in testing is that testers are more likely to identify different types of failures and defects compared to developers, due to their varied backgrounds, technical viewpoints, and potential biases, including cognitive bias

Thus:
a) Is not correct
b) Is correct. The list entries showing benefits are ii and v
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is correct. The primary benefit of independence in testing is that testers are more likely to identify different types of failures and defects compared to developers, due to their varied backgrounds, technical viewpoints, and potential biases, including cognitive bias. However, the main disadvantage of independence in testing is that testers may become isolated from the development team, leading to communication problems, a lack of collaboration, and potentially an adversarial relationship, with testers being blamed for delays and bottlenecks in the release process
b) Is not correct. A developer’s familiarity with the code does not mean that they rarely find defects in it, instead this familiarity means they can efficiently find many defects in their own code. And, rather than developers and testers having a shared background, developers having a different background to testers is normally cited as the reason that testers and developers find different kinds of defects
c) Is not correct. Testing can be conducted at different levels of independence, ranging from no independence for the author to very high independence for testers from outside the organization. In most projects, multiple levels of independence are utilized, with developers performing component and component integration testing, the test team performing system and system integration testing, and business representatives performing acceptance testing. So, testers can be in the developer’s team and do not need to come from outside the organization. Knowledge of the application domain will change from case-to-case and is not dependent on the level of independence
d) Is not correct. Testing can be conducted at different levels of independence, ranging from no independence for the author to very high independence for testers from outside the organization, with testers from outside the developer’s team generally more independent than testers from within the team. However, there is more reason to believe that testers from outside the team are likely to be more isolated from the developers and so are more likely to be blamed for delays in product release

Explanation / Rationale

a) Is not correct. Confirmation testing to check that the updates have resulted in a correct implementation is necessary, however, it would then be sensible to perform regression testing to ensure that no defects have been introduced or uncovered in unchanged areas of the system
b) Is correct. Confirmation testing will check that the updates have resulted in a correct implementation, and then regression testing will be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system
c) Is not correct. Regression testing should be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system when the update was made, however it is also necessary to perform confirmation testing that will check that the updates have resulted in a correct implementation
d) Is not correct. Confirmation testing will check that the updates have resulted in a correct implementation, and regression testing will be used to ensure that no defects have been introduced or uncovered in unchanged areas of the system. However, when performed (i.e., when an update needs to be tested), confirmation testing precedes regression testing

Explanation / Rationale

a) Is not correct. This sequence of five events covers 4 different valid transitions (both “NotAvailable” events correspond to the same transition between S1 and S3). This test case covers 4 out of 7 valid transitions
b) Is correct. This sequence of five events covers 5 different transitions (the first “Available” event corresponds to a transition between S1 and S2, and the second “Available” event corresponds to a transition between S3 and S2, so two different transitions are covered). This test case covers 5 out of 7 valid transitions and achieves the highest valid transitions coverage
c) Is not correct. This sequence of five events covers 3 different transitions (both “Available” events correspond to the same transition from S1 to S2; both “ChangeRoom” events correspond to the same transition from S2 to S1). This test case covers 3 out of 7 valid transitions
d) Is not correct. This sequence of five events does not represent a feasible test case, because after “Cancel” the system ends up in the End state and no further valid transitions can be executed

Explanation / Rationale

a) Is not correct. Testing quadrants have nothing to do with describing the relationships between test levels
b) Is not correct. Testing quadrants cannot help in assessing any type of coverage
c) Is correct. Testing quadrants allow managers and other stakeholders to understand the relationships between test types, the activities they support (team support or product critique), and the viewpoint they are focused on (business- or technology-facing)
d) Is not correct. Testing quadrants is not a psychological model

Explanation / Rationale

The ‘absence-of-defects fallacy’ is concerned with the idea that ensuring correctness in accordance with the requirements (i.e., verifying the absence of implementation defects) does not guarantee user satisfaction with the system. To address this it is also necessary to validate that the system meets users' needs and expectations, fulfills business objectives, and outperforms competing systems.
a) Is not correct. The ‘testing shows the presence, not the absence of defects’ principle explains that while testing can detect the existence of defects in the test object, it is not possible to demonstrate that there are no defects and, therefore, guarantee its correctness. Therefore, explaining that it is not possible for testing to show the absence of defects would partially address this principle, not the ‘absence-of-defects’ fallacy
b) Is correct. By supporting the end user to perform acceptance testing it should be possible to validate that the system meets users' needs and expectations
c) Is not correct. It is not possible to ensure that no implementation defects remain in the delivered system as the ‘testing shows the presence, not the absence of defects’ principle explains that while testing can detect the existence of defects in the test object, it is not possible to demonstrate that there are no defects and, therefore, guarantee its correctness
d) Is not correct. Modifying tests that cause no failures to ensure few defects remain is one way to address the ‘tests wear out’ principle. This principle is concerned with the idea that repeating identical tests on unaltered code is unlikely to uncover novel defects and therefore, modifying tests may be essential. This will not validate that the system meets users' needs and expectations

Explanation / Rationale

a) Is not correct. Quality should be the responsibility of everyone working on the project and not the sole responsibility of the test team
b) Is not correct. First, it is not a benefit if an external test team does not meet delivery deadlines, and second, there is no reason to believe that external test teams will feel they do not have to meet strict delivery deadlines
c) Is not correct. It is bad practice for the test team to work in complete isolation, and we would expect an external test team to be concerned with changing project requirements and communicating well with developers
d) Is correct. Specifications are never perfect, meaning that assumptions will have to be made by the developer. An independent tester is useful in that they can challenge and verify the assumptions and subsequent interpretation made by the developer

Explanation / Rationale

Considering each of the listed tool categories and their descriptions:

A. Static testing tools – support the tester in performing reviews and static analysis (4)
B. Tools supporting scalability and deployment standardization – For example, virtual machines, containerization tools (3)
C. DevOps tools – support the DevOps delivery pipeline, workflow tracking, automated build process(es), continuous integration/continuous delivery (CI/CD) (1)
D. Collaboration tools – facilitate communication (2)

Thus:
a) Is not correct
b) Is not correct
c) Is correct. The correct match is: 1C, 2D, 3B, 4A
d) Is not correct

Explanation / Rationale

a) Is not correct. Scope creep is an example of a project risk related to technical issues
b) Is correct. Poor architecture is an example of a product risk since it refers to a product characteristic
c) Is not correct. Cost-cutting is an example of a project risk, related to organizational issues
d) Is not correct. Poor tool support is an example of a project risk related to technical issues
e) Is correct. Response time too long is an example of a product risk since it refers to a product characteristic

Explanation / Rationale

Because TC1 and TC3 failed in Execution 1 (i.e., test (1) and test (3)), test (4) and test (6) are confirmation tests.
Because TC2 and TC3 failed in Execution 2 (i.e., tests (5) and (6)), test (8) and test (9) are also confirmation tests.
TC2 passed in Execution 1 (i.e., test (2)), so test (5) is a regression test.
TC1 passed in the Execution 2 (i.e., test (4)), so test (7) is also a regression test.
Thus:
a) Is not correct
b) Is correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. The test case is related to viewing previous orders in the order history
b) Is not correct. The test case is related to viewing previous orders
c) Is not correct. The test case is related to viewing previous orders in the order history
d) Is correct. The test case is related to the registration process, which is not discussed in the user story. The user story is about viewing previous orders

Explanation / Rationale

a) Is not correct. Risk monitoring is part of risk control, not risk analysis
b) Is not correct. Risk identification itself does not allow us to implement risk mitigation activities. The mitigating actions are defined during the risk control phase
c) Is correct. This is an example of how risk analysis influences the thoroughness and scope of testing
d) Is not correct. Coverage items are derived using test techniques, not through risk analysis

Explanation / Rationale

a) Is not correct. Retrospectives are more useful for identifying improvement opportunities and have little importance for clients
b) Is not correct. Business representatives are not giving feedback about the product itself. Therefore, there is no financial gain to the organization
c) Is correct. Regularly conducted retrospectives, when appropriate follow up activities occur, are critical to continual improvement of development and testing
d) Is not correct. Courage and respect are values of Extreme Programming and are not closely related to retrospectives

Explanation / Rationale

a) Is not correct. To ensure successful reviews, it's important to secure management's support for the review process, however that does not mean that they should participate as reviewers
b) Is correct. To ensure successful reviews, it's important to break the work product into parts that are small enough to be reviewed in a reasonable timescale to prevent reviewers from losing focus during individual review or review meetings
c) Is not correct. To ensure successful reviews, it's important to clearly define objectives and measurable exit criteria, without evaluating participants
d) Is not correct. To ensure successful reviews, it's important to break down the review into smaller chunks to prevent reviewers from losing focus during individual review or review meetings. So you should not plan to cover one document per review

Explanation / Rationale

a) Is not correct. This is the task of the review leader
b) Is correct. This is the task of the management in a formal review
c) Is not correct. This is the task of the moderator
d) Is not correct. This is the task of the scribe

Explanation / Rationale

Considering each of the listed test activities and their tasks:

A. Test analysis - To identify the features that require testing, the test basis is analyzed and defined as test conditions, which are then prioritized along with related risks. During this test analysis, defects in the test basis are typically uncovered, and the test object's testability may also be assessed. (Task 4)
B. Test design - Involves using test conditions to create test cases and other necessary testware, such as test data requirements and test charters for exploratory testing. (Task 1)
C. Test implementation - Test procedures, such as manual and automated test scripts, are created from test cases and may be assembled into test suites. Test procedures are prioritized and arranged in a test execution schedule. (Task 3)
D. Test completion - Occurs at project milestones, such as release, end of iteration or end of test level. Testware is identified and archived or handed to the appropriate teams for reuse, the test environment is shut down, and the test activities are analyzed for lessons learned and future improvements. (Task 2)

Thus:
a) Is not correct
b) Is correct. The CORRECT match is: 1B, 2D, 3C, 4A
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
b) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
c) Is not correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach
d) Is correct. The paragraph contains information on test levels and exit criteria, which are part of the test approach

Explanation / Rationale

a) Is correct. Performing only black-box testing does not provide a measure of actual code coverage. White-box coverage measures provide an objective measurement of coverage and provide the necessary information to allow additional tests to be generated to increase this coverage, and subsequently increase confidence in the code
b) Is not correct. This statement is correct, but it has nothing to do with black-box testing
c) Is not correct. In general there are no subsumes relationships between white-box and black-box techniques
d) Is not correct. White-box techniques are used to design tests based on the test object itself, while black-box techniques are used to design tests based on the specification. Therefore, there is no relation between coverage items derived from these two types of techniques

Explanation / Rationale

a) Is not correct. QA concentrates on process improvement and implementation, using a preventive approach to avoid errors and defects, while testing is a form of QC that is used to detect defects
b) Is correct. QC aims to achieve appropriate levels of quality by focusing on identifying and correcting product defects. Testing is a significant part of QC and helps to uncover these defects
c) Is not correct. Although testing is a significant part of QC and helps to uncover defects, other (non-testing) techniques utilized in QC include formal methods like model checking and proof of correctness, as well as simulation and prototyping
d) Is not correct. QA concentrates on process improvement and implementation, using a preventive approach to avoid errors and defects, while testing is a form of QC that is used to detect defects

Explanation / Rationale

a) Is not correct. The organization’s marketing team is unlikely to perform much testing (although in some organizations they may be involved with acceptance testing), so their average level of experience (most of which would be in marketing) is not likely to impact how testing is performed for a given test object
b) Is not correct. The level of knowledge of users that a new system is being built for them is unlikely to affect how testing is performed. Any user involvement that could affect how testing is performed is more likely to be as a result of decisions made by the testers, customer and project manager
c) Is correct. The number of years’ experience of the members of the performance testing team will help to determine the capabilities and knowledge (e.g., of different tools and defect types) that the team members will apply when they are testing
d) Is not correct. The organizational structure of the different end users (who may be varied) will change between users. So, it may not even be known when the application is being tested, and the end user’s organizational structure can thus have little effect on how the testing is performed

Explanation / Rationale

The following three transitions:

“REQUESTING -> CONFIRMED”
“WAITING LIST -> CONFIRMED”
“WAITING LIST -> END”

cannot appear in the same test case, which suggests that at least three test cases are required. All the other transitions can appear in combination with one or more of these three transitions, so we need a minimum of three test cases. In fact, only three sequences are possible:

TC1: START (Room request) → REQUESTING (Available) → CONFIRMED (Pay) → END
TC2: START (Room request) → REQUESTING (Not available) → WAITING LIST (Available) → CONFIRMED (Pay) → END
TC3: START (Room request) → REQUESTING (Not available) → WAITING LIST (Cancel) → END

Thus:
a) Is correct
b) Is not correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is not correct. Strong communication skills, active listening, and teamwork abilities enable a tester to interact effectively with all stakeholders, however a deep knowledge of a variety of computer games that allowed them to get on well with one developer is not an example of a generic skill useful to testers
b) Is correct. Domain knowledge that can be used to understand and communicate with end-users and business representatives is one of the generic skills required by testers. A tester with experience as a pilot would make them better able to appreciate the acceptance criteria for the helicopter control system
c) Is not correct. Although programming skills could be considered as technical knowledge which can increase efficiency when utilizing some test tools, it is unlikely that these skills would improve their communication with business analysts
d) Is not correct. Although thoroughness, attention to detail, curiosity, and a methodical approach to identifying hard-to-find defects are all useful generic skills for testers, it is doubtful they would be generating test cases prior to starting exploratory testing. This is because one of the main tenets of exploratory testing is that the test cases are generated during the testing, not scripted in advance

Explanation / Rationale

a) Is not correct. Planning poker can estimate effort for a user story that is already written. It does not help in understanding what should be delivered
b) Is not correct. Reviews are not a collaborative user story writing practice
c) Is not correct. Iteration planning is a project-related practice, used to plan the work, not to understand what needs to be delivered
d) Is correct. Conversation explains how the software will be used and often allows the team to define meaningful acceptance criteria, thus obtaining a shared vision of what should be delivered

Explanation / Rationale

Error guessing is about anticipating the errors, defects and failures based on the tester’s knowledge.
a) Is not correct. This is an example of anticipating the developer’s error
b) Is not correct. This is an example of anticipating the defect
c) Is correct. This is an example of a potential root cause of a defect, which is neither an error, defect nor failure, and difficult for the tester to anticipate
d) Is not correct. This is an example of anticipating a failure, perhaps based on experience of previous systems in this application domain

Explanation / Rationale

a) Is correct. Test design involves using test conditions to create test cases and other necessary testware, such as test data requirements and test charters for exploratory testing. Test environment requirements are also specified, including the necessary infrastructure and tools
b) Is not correct. Test execution involves executing test cases (as part of test procedures), however it does not directly cover the other testware mentioned in the question, such as test data requirements, test environment requirements and test conditions
c) Is not correct. Test analysis is used to identify the features that require testing. The test basis is analyzed and defined as test conditions, which are then prioritized along with related risks. While this activity involves working with test conditions, it does not cover the other testware mentioned in the question, such as test data requirements, test environment requirements and test cases
d) Is not correct. Test implementation includes the generation of test procedures, such as manual and automated test scripts, which are created from test cases and may be assembled into test suites. Test procedures are prioritized and arranged in a test execution schedule. Test data is created, and the test environment built, and its set up verified. While this activity involves explicitly working with test cases, and may use test data requirements and test environment requirements to create test data and the test environment, it does not cover test conditions

Explanation / Rationale

a) Is not correct. In agile software development, deliverables are produced in each iteration, and the frequent delivery of increments necessitates extensive regression testing. Although some (or all) of this regression testing may be automated, the regression testing (automated or not) cannot be replaced by system test automation
b) Is correct. If a sequential development model is used, then early in the lifecycle no code is available for execution, and so during this time static testing (e.g., reviews) is performed. Later in the lifecycle, when code is available for execution, dynamic testing is possible. Note, however, that preparation for dynamic testing will often occur early in any software development lifecycle
c) Is not correct. If an iterative development model, like agile software development, is used, then component tests may well be used for regression testing for each iteration. In which case, there is a strong argument for automating these component tests, which will have to be run frequently, and there is unlikely to be a strong argument for developers performing these component tests manually
d) Is not correct. In most incremental development models, deliverables are produced in each increment, requiring both static and dynamic testing at all test levels for each increment delivered

Explanation / Rationale

a) Is not correct. DevOps generally increases the visibility of non-functional quality characteristics, such as performance and reliability
b) Is not correct. Automated processes like continuous integration/continuous delivery (CI/CD) used in DevOps facilitate stable test environments
c) Is not correct. Automated processes like CI/CD used in DevOps generally reduce the need for manual testing
d) Is correct. DevOps implementation can pose several risks and challenges, including the need to define and set up the delivery pipeline, introduce and maintain CI/CD tools, and establish and maintain test automation

Explanation / Rationale

From the graph we have:

A(4)=6 and A(3)=8 (the last two gray boxes).

From the formula we obtain:

E(5) = (3*A(4) + A(3)) / 4 = (3*6+8) / 4 = 26 / 4 = 6.5 person-days.

Thus:
a) Is not correct
b) Is not correct
c) Is correct
d) Is not correct

Explanation / Rationale

Considering:

• The test basis for acceptance testing is the user’s business needs (1D)
• Communication between components is tested during component integration testing (2B)
• Failures in logic can be found during component testing (3A)
• Business rules are the test basis for system testing (4C)

Thus:
a) Is correct
b) Is not correct
c) Is not correct
d) Is not correct

Explanation / Rationale

a) Is correct. Adding this information allows the developer to use the same input data, so it is more likely they will be able to reproduce the failure quickly and so identify the defect faster
b) Is not correct. Adding the value of Priority will not help in reproducing the defect itself
c) Is not correct. Although some of this information may be of value, adding the memory dumps and database snapshots after each step will be too much, because most of these artefacts will contain useless information for the developer, and make the report less readable. It will also require the developer to spend a lot of time analyzing this information, which will lengthen the repair process
d) Is not correct. The question was about helping the developer to reproduce the defect observed for a specific environment configuration

Explanation / Rationale

a) Is correct. 19 covers the “no discount” partition, 20 covers the “50% discount” partition, and 30 covers the “10% discount” partition. These three values cover all three of the valid equivalence partitions
b) Is not correct. 11 and 12 cover the “no discount” partition, while 20 covers the “50% discount” partition, so covering two of the three valid equivalence partitions
c) Is not correct. 1 covers the “no discount” partition, while 10 and 50 cover the “10% discount” partition. The “50% discount” partition is not covered, so overall two of the three valid equivalence partitions are covered
d) Is not correct. 29 and 31 cover the “no discount” partition, while 10 and 30 cover the “10% discount” partition. The “50% discount” partition is not covered, so overall two of the three valid equivalence partitions are covered