Defect Density

Defect Density

Defect Density Definition
Defect Density is the number of confirmed defects detected in software/component during a defined period of development/operation divided by the size of the software/component.

Elaboration
The 'defects' are:

confirmed and agreed upon (not just reported).
Dropped defects are not counted.

The ‘period’ might be for one of the following:

for a duration (say, the first month, the quarter, or the year).
for each phase of the software life cycle.
for the whole of the software life cycle.
The ‘size’ is measured in one of the following:

Function Points (FP)
Source Lines of Code


Defect Density Formula


Defect Density Uses
For comparing the relative number of defects in various software components so that high-risk components can be identified and resources focused towards them
For comparing software/products so that ‘quality’ of each software/product can be quantified and resources focused towards those with low quality.

Defect Injection / Defect Seeding

Defect Injection is also known as 'Defect Seeding', 'Fault injection'. The
Process of adding known defects to the existing ones is
called as Defect Seeding. The Idea is while detecting the
known bugs unknown bugs might be detected. The goal is to
determine the Bug Detection Rate.

What is Defect Seeding?
Answer
# 1 Defect Seeding : For identify the Capability of tester
team , One Group will insert Defect in appliaction ,This
Bug will found by another Group

Example : In Real Appliaction this group will find 650 bug
but in defect seeding software they will find 30 bug out of
50 Bug total Bug in real appliaction 50*650/30 = 1084 bug
is available in Appliaction



What is Defect Seeding?
Answer
# 2 In this method, intentionally the developer/lead will
introduce the bugs in to product... we dont know in which
module they will occur.. So we have to do regression
testing to identify that bugs as well as residual bugs(more
bugs). The main intention of this is to get more bugs.

Difference between test case and test scenario and test script

Test Scenario:- A test scenario is almost like a story like example "a user enters into the application from login window by entering valid user name and password. After entering he will click on module Payslip and clicks on latest payslip feature to view his latest payslip". Any test scenario will contain a specific goal.

Test case:- It is the set of test inputs, execution conditions and expected results developed to test a perticular functionality.

Test cases are often referred to as test scripts, particularly when written. Written test cases are usually collected into test suites.

A test case can be derived from a scenario .For the above scenario we can write a test case like :

Test Case # 1:

S.No Steps Expected

1 Open the login window Login window is open

2 Enter valid UN & Pwd Application should be open

3 Click on Payslip Features in payslip should be displayed

4 Click on latest payslip feature It should open latest payslip window

Above is a positive test case and a negative test case can also be prepared.A test case is prepared and executed with a goal to find the hidden defects with different possibilities.

Test Script:- Manually. These are more commonly called test cases.
Automated Short program written in a programming language used to test part of the functionality of a software system. Test scripts written as a short program can either be written using a special automated functional GUI test tool (such as HP QuickTest Professional, Borland SilkTest, and Rational Robot) or in a well-known programming language (such as C++, C#, Tcl, Expect, Java, PHP, Perl, Python, or Ruby).

Test Suite:- In software development, a test suite, less commonly known as a validation suite, is a collection of test cases that are intended to be used to test a software program to show that it has some specified set of behaviours. A test suite often contains detailed instructions or goals for each collection of test cases and information on the system configuration to be used during testing.

Occasionally, test suites are used to group similar test cases together. A system might have a smoke test suite that consists only of smoke tests or a test suite for some specific functionality in the system. It may also contain all tests and signify if a test should be used as a smoke test or for some specific functionality.

An executable test suite is a test suite that can be executed by a program. This usually means that a test harness, which is integrated with the suite, exists. The test suite and the test harness together can work on a sufficiently detailed level to correctly communicate with the system under test (SUT).


Use Case: A sequence of transactions in a dialogue between a user and the system with a tangible result.

Test Scenario: It is a document specifying a sequence of actions for the execution of a test.

Test Case: A set of input values,test execution preconditions,expected esults and execution postconditions developed for a particular objective or test condition,such as to verify compliance witha specific requirement