Equivalence partitioning and boundary value analysis are test design techniques that are most appropriate for testing the login page of a web site. The page contains fields for user name and password, which are input values that can be divided into partitions of equivalent data. Equivalence partitioning is a technique that divides the input data and output results of a software component into partitions of equivalent data. Each partition should contain data that is treated in the same way by the component. Equivalence partitioning can be used to reduce the number of test cases by selecting one representative value from each partition. Boundary value analysis is a technique that tests boundary values between partitions of equivalent data. Boundary values are values at the edge of an equivalence partition or at the smallest incremental distance on either side of an edge. Boundary value analysis can be used to detect defects caused by incorrect handling of boundary conditions. For example, for testing the user name field, we can identify two equivalence partitions: valid user name (existing and correct) and invalid user name (non-existing or incorrect). The boundary values for these partitions are the minimum and maximum length of user name allowed by the system.

Decision table testing and state transition testing are not suitable for testing the login page of a web site, as they are more applicable for testing components that have multiple inputs and outputs that depend on logical combinations of conditions or events. Decision table testing is a technique that shows combinations of inputs and/or stimuli (causes) with their associated outputs and/or actions (effects). State transition testing is a technique that models how a system transitions from one state to another depending on events or conditions.

Exploratory testing and statement coverage are not suitable for testing the login page of a web site, as they are more applicable for testing components that require learning, creativity and intuition or structural analysis. Exploratory testing is an approach to testing that emphasizes learning, test design and test execution at the same time. Exploratory testing relies on the tester’s skills, creativity and intuition to explore the software under test and discover defects. Statement coverage is a type of structural testing that measures how many statements in a program have been executed by a test suite. Statement coverage can be used to assess the adequacy or completeness of a test suite.

Decision coverage and fault attack are not suitable for testing the login page of a web site, as they are more applicable for testing components that have complex logic or potential errors. Decision coverage is a type of structural testing that measures how many decision outcomes in a program have been executed by a test suite. Decision coverage can be used to assess the adequacy or completeness of a test suite. Fault attack is a type of functional testing that deliberately introduces faults into a system in order to provoke failures or errors. Verified References: [A Study Guide to the ISTQB® Foundation Level 2018 Syllabus - Springer], Chapter 4, page 34-46; Chapter 5, page 47-48.