Testing Concepts

21. What is DRE?

To measure test effectiveness a powerful metric is used to measure test effectiveness known as DRE (Defect Removal Efficiency).

 From this metric we would know how many bugs we have found from the set of test cases. Formula for calculating DRE is

DRE=Number of bugs while testing  / number of bugs while testing + number of bugs found by user

22. What are Test comparators?

Is it really a test if you put some inputs into some software, but never look to see whether the software produces the correct result? The essence of testing is to check whether the software produces the correct result, and to do that, we must compare what the software products to what it should produce.

A test comparator helps to automate aspects of that comparison.

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JAVA QUESTIONS

DAY:12

What is ServletConfig?

·         ServletConfig available in javax.servlet.*; package

·         ServletConfig object is one per servlet class

·         Object of ServletConfig will be created during initialization process of the servlet

·         This Config object is public to a particular servlet only

·         Scope: As long as a servlet is executing, ServletConfig object will be available, it will be destroyed once the servlet execution is completed.

·         We should give request explicitly, in order to create ServletConfig object for the first time

·         In web.xml – <init-param> tag will be appear under <servlet-class> tag

What is ServletContext?

·         ServletContext available in javax.servlet.*; package

·         ServletContext object is global to entire web application

·         Object of ServletContext will be created at the time of web application deployment

·         Scope: As long as web application is executing, ServletContext object will be available, and it will be destroyed once the application is removed from the server.

·         ServletContext object will be available even before giving the first request

·         In web.xml – <context-param> tag will be appear under <web-app> tag

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Testing Concepts

23. What is exploratory testing?

 Exploratory testing is a hands-on approach in which testers are involved in minimum planning and maximum test execution. The planning involves the creation of a test charter, a short declaration of the scope of a short (1 to 2 hour) time-boxed test effort, the objectives and possible approaches to be used.

The test design and test execution activities are performed in parallel typically without formally documenting the test conditions, test cases or test scripts. This does not mean that other, more formal testing techniques will not be used.

 For example, the tester may decide to use boundary value analysis but will think through and test the most important boundary values without necessarily writing them down. Some notes will be written during the exploratory-testing session, so that a report can be produced afterwards.

24. What is white box testing and list the types of white box testing?

White box testing technique involves selection of test cases based on an analysis of the internal structure (Code coverage, branches coverage, paths coverage, condition coverage etc.)  Of a component or system. It is also known as Code-Based testing or Structural testing.  Different types of white box testing are

Statement Coverage

Decision Coverage

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JAVA QUESTIONS

What are available drivers in JDBC?

JDBC technology drivers fit into one of four categories:

1.     A JDBC-ODBC bridge provides JDBC API access via one or more ODBC drivers. Note that some ODBC native code and in many cases native database client code must be loaded on each client machine that uses this type of driver. Hence, this kind of driver is generally most appropriate when automatic installation and downloading of a Java technology application is not important. For information on the JDBC-ODBC bridge driver provided by Sun, see JDBC-ODBC Bridge Driver.

2.     A native-API partly Java technology-enabled driver converts JDBC calls into calls on the client API for Oracle, Sybase, Informix, DB2, or other DBMS. Note that, like the bridge driver, this style of driver requires that some binary code be loaded on each client machine.

3.     A net-protocol fully Java technology-enabled driver translates JDBC API calls into a DBMS-independent net protocol which is then translated to a DBMS protocol by a server. This net server middleware is able to connect all of its Java technology-based clients to many different databases. The specific protocol used depends on the vendor. In general, this is the most flexible JDBC API alternative. It is likely that all vendors of this solution will provide products suitable for Intranet use. In order for these products to also support Internet access they must handle the additional requirements for security, access through firewalls, etc., that the Web imposes. Several vendors are adding JDBC technology-based drivers to their existing database middleware products.

4.     A native-protocol fully Java technology-enabled driver converts JDBC technology calls into the network protocol used by DBMSs directly. This allows a direct call from the client machine to the DBMS server and is a practical solution for Intranet access. Since many of these protocols are proprietary the database vendors themselves will be the primary source for this style of driver. Several database vendors have these in progress.

What is the Difference between Externalizable and Serializable Interfaces?

Serializable is a marker interface therefore you are not forced to implement any methods, however Externalizable contains two methods readExternal() and writeExternal() which must be implemented. Serializable interface provides a inbuilt serialization mechanism to you which can be in-efficient at times. However Externilizable interface is designed to give you greater control over the serialization mechanism. The two methods provide you immense opportunity to enhance the performance of specific object serialization based on application needs. Serializable interface provides a default serialization mechanism, on the other hand, Externalizable interface instead of relying on default Java Serialization provides flexibility to control this mechanism. 

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Testing Concepts

19. When do we prepare RTM (Requirement traceability matrix), is it before test case designing or after test case designing?

It would be before test case designing. Requirements should already be traceable from Review activities since you should have traceability in the Test Plan already. This question also would depend on the organization.

 If the organizations do test after development started then requirements must be already traceable to their source. To make life simpler use a tool to manage requirements.

20. Why we split testing into distinct stages?

We split testing into distinct stages because of following reasons,

Each test stage has a different purpose

It is easier to manage testing in stages

We can run different test into different environments

Performance and quality of the testing is improved using phased testing.

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JAVA QUESTIONS

What is the difference between sleep(), suspend() and wait() ?

Thread.sleep() takes the current thread to a "Not Runnable" state for specified amount of time. The thread holds the monitors it has acquired. For example, if a thread is running a synchronized block or method and sleep method is called then no other thread will be able to enter this block or method. The sleeping thread can wake up when some other thread calls t.interrupt on it. Note that sleep is a static method, that means it always affects the current thread (the one executing sleep method). A common mistake is trying to call t2.sleep() where t2 is a different thread; even then, it is the current thread that will sleep, not the t2 thread. thread.suspend() is deprecated method. Its possible to send other threads into suspended state by making a suspend method call. In suspended state a thread keeps all its monitors and can not be interrupted. This may cause deadlocks therefore it has been deprecated. object.wait() call also takes the current thread into a "Not Runnable" state, just like sleep(), but with a slight change. Wait method is invoked on a lock object, not thread.

What are the alternatives to Serialization? If Serialization is not used, is it possible to persist or transfer an object using any other approach?

In case, Serialization is not used, Java objects can be serialized by many ways, some of the popular methods are listed below:

·        Saving object state to database, this is most common technique used by most applications. You can use ORM tools (e.g. hibernate) to save the objects in a database and read them from the database.

·        Xml based data transfer is another popular mechanism, and a lot of XML based web services use this mechanism to transfer data over network. Also a lot of tools save XML files to persist data/configurations.

·        JSON Data Transfer - is recently popular data transfer format. A lot of web services are being developed in JSON due to its small footprint and inherent integration with web browser due to JavaScript format.   

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Testing Concepts

17.  When should testing be stopped?

It depends on the risks for the system being tested. There are some criteria bases on which you can stop testing.

Deadlines (Testing, Release)

Test budget has been depleted

Bug rate fall below certain level

Test cases completed with certain percentage passed

Alpha or beta periods for testing ends

18. Why we use decision tables?

The techniques of equivalence partitioning and boundary value analysis are often applied to specific situations or inputs. However, if different combinations of inputs result in different actions being taken, this can be more difficult to show using equivalence partitioning and boundary value analysis, which tend to be more focused on the user interface.

The other two specification-based techniques, decision tables and state transition testing are more focused on business logic or business rules. A decision table is a good way to deal with combinations of things (e.g. inputs).

This technique is sometimes also referred to as a 'cause-effect' table. The reason for this is that there is an associated logic diagramming technique called 'cause-effect graphing' which was sometimes used to help derive the decision table.

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