Top 50 Cobertura interview questions and answers

Table of Contents

1) Where Does The Name “cobertura” Come From?

“Cobertura” is the Spanish and Portuguese word for “coverage.” We were trying to avoid acronyms and coffee references. It’s not too hard to associate the word “cobertura” with the word “coverage,” and it even has a bit of a zesty kick to it!

2) What Is Cobertura?

Cobertura is an open source tool that measures test coverage by instrumenting a code base and tracking the percentage of code that are executed as the test suite runs. It is based on jcoverage. In addition to identifying untested code and locating bugs, Cobertura can optimize code by flagging dead and unreachable code.

Cobertura monitors tests by instrumenting the bytecode with extra statements to log which lines are and are not being reached as the test suite executes. It then produces a report in HTML or XML that shows exactly which packages, classes, methods, and individual lines of code are not being tested.

3) What About Emma?

We haven’t used it very much, but it looks like it does a pretty good job. Judging from the sample on the Emma web page, we think the Cobertura HTML reports are a bit easier to digest. It looks like Emma has some nice usability features, such as the ability to instrument all classes in a jar file with one command. A little friendly competition never hurt anyone.

4) What Do I Need To Use Cobertura?

A computer with Java 1.3 or newer. We have run Cobertura on Windows XP and Linux (Fedora Core 4) using the 1.4.2 JDK. However, it should work on any platform and with any 1.3 or newer JDK. The Cobertura download packages include all the dependencies you’ll need (ASM, log4j, etc.)

5) What Is Code Complexity And Why Should I Care About It?

McCabe’s cyclomatic code complexity algorithm is used to determine how “complex” a given piece of code is. As code becomes more complex, it becomes more error prone. If a class has a high complexity number, then that class is a good target for additional test coverage.

6) When I Generate Coverage Reports, Why Do They Always Show 100% Coverage Everywhere?

Cobertura is probably using the wrong .ser file when generating the reports. When you instrument your classes, Cobertura generates a .ser file containing basic information about each class. As your tests run, Cobertura adds additional information to this same data file. If the instrumented classes can not find the data file when running then they will create a new one. It is important that you use the same cobertura.ser file when instrumenting, running, and generating reports.

The best way to do this is to specify the location of the data file when running your tests. You should pass the -Dnet.sourceforge.cobertura.datafile=${basedir}/cobertura.ser sysproperty to the JUnit task.

Another common problem is that the cobertura.ser file is deleted, but the previously instrumented classes are not also deleted. Any time you delete your coverage data file you should also deleted all instrumented classes.

7) Why Is Cobertura Causing Me To Have Classpath Conflicts With Asm?

Cobertura uses ASM to modify your bytecode. There are a few other popular programs that use ASM; Groovy and Hibernate, to name two. You could have problems if Cobertura uses a different version of asm and you add both versions to your classpath.

Cobertura only uses ASM when instrumenting. Cobertura does not need ASM in your classpath when running tests. If you’re seeing classpath conflicts, just make sure the asm jar that comes with Cobertura is used only by Cobertura, and only when instrumenting.

8) Is It Possible To Graphically Show My Test Coverage Over Time?

Yes, using QALab. From their website, QALab “allows developers, architects and project managers alike to be presented with a trend of the QA statistics of their project.”

9) I Have Automated Tests That Use Httpunit/htmlunit/empirix/rational Robot, Can I Use Cobertura?

Yes! The process is a bit more involved, but the concept is the same. First instrument your compiled classes. Then create your war file. Then deploy the war file into your application server (Tomcat, JBoss, WebLogic, WebSphere, etc). Now run your tests.

As your classes are accessed, they will create a “cobertura.ser” file on the disk. You may need to dig around a bit to find it. Cobertura puts this file in what it considers to be the current working directory. Typically this is the directory that the application server was started from (for example, C:Tomcatbin) Note: This file is not written to the disk until the application server exits. See below for how to work around this.

Now that you know where the cobertura.ser file is, you should modify your deploy step so that it moves the original cobertura.ser to the appropriate directory in your application server, and then moves it back when finished testing. Then run cobertura-report.

10) I’m Using Jboss. When I Stop The Server, The Coverage Data File Is Not Written. Or The Coverage Data File Is 0 Bytes. Or Cobertura-report And Cobertura-merge Complain That The Coverage Data File Is Invalid (possibly Throwing An Eofexception).?

Cobertura only writes the coverage data file at shutdown. It does this by adding a shutdown hook with Runtime.getRuntime().addShutdownHook(). JBoss has its own shutdown hook that calls System.halt() when its finished. If the JBoss shutdown hook finishes before the Cobertura shutdown hook, then the call to System.halt() causes the JVM to halt and the cobertura.ser file will be incomplete.

To fix this, set -Djboss.shutdown.forceHalt=false when starting JBoss.

11) Cobertura Only Writes The Coverage Data File When The Application Server Shuts Down. We Do Not Want To Stop Our Application Server After Running Our Tests.?

It is possible to instruct Cobertura to write the data file. One of your classes should call the static method net.sourceforge.cobertura.coveragedata.ProjectData.saveGlobalProjectData().

For example: you could add something like this to a “logout” method in your web application:

try {
String className = “net.sourceforge.cobertura.coveragedata.ProjectData”;
String methodName = “saveGlobalProjectData”;
Class saveClass = Class.forName(className);
java.lang.reflect.Method saveMethod = saveClass.getDeclaredMethod(methodName, new Class[0]);
saveMethod.invoke(null,new Object[0]);
} catch (Throwable t) {
}

12) What is cobertura used for?

Cobertura is a free Java tool that calculates the percentage of code accessed by tests. It can be used to identify which parts of your Java program are lacking test coverage. It is based on jcoverage

13) How do you set up cobertura?

Configuring the Cobertura Plugin
Install the cobertura plugin (via Manage Jenkins -> Manage Plugins)
Configure your project’s build script to generate cobertura XML reports (See below for examples with Ant and Maven2)
Enable the “Publish Cobertura Coverage Report” publisher.
Specify the directory where the coverage.

14) How do I get cobertura report?

Cobertura Code Coverage Report

Maven will generate the Cobertura code coverage report at ${project}/target/site/cobertura/index. html .

15) Is cobertura open-source?

Cobertura is an open-source tool for measuring code coverage.

16) How do you use EclEmma in STS?

Option 1: Install from Eclipse Marketplace Client
From your Eclipse menu select Help → Eclipse Marketplace.
Search for “EclEmma”.
Hit Install for the entry “EclEmma Java Code Coverage”.
Follow the steps in the installation wizard.
From your Eclipse menu select Help → Install New Software.

17) How is EclEmma used to determine coverage?

EclEmma retrieves code coverage metrics as conveniently as you execute your test suites directly in the IDE . The plugin can be easily installed from its update site at http://update.eclemma.org/ on any Eclipse installation of version 3.5 or above. It is also available from the Eclipse Marketplace.

18) How does EclEmma check code coverage in STS?

Integration of JACOCO Code Coverage Plugin in Eclipse/STS
Go to IDE top header Help->Eclipse Market Place it will open the pop up for Eclipse Market Place.
Type text as “Code Coverage” in search text box and click “Go” button. You will get below screen.

19) How is code coverage calculated?

How is it measured? To calculate the code coverage percentage, simply use the following formula: Code Coverage Percentage = (Number of lines of code executed by a testing algorithm/Total number of lines of code in a system component) * 100.

20) How do I increase code coverage in STS?

For the code coverage to increase , one would need to run the tests with the coverage enabled and then view the report generated locally to see the areas covered by jacoco during its coverage parse, then from these one would see the methods (per class) that needs to be covered from the view of the jacoco agent.

21) How do I add insurance to STS?

Right-click on project > Properties > Coverage to enable code coverage. Then, right-click on project > Run Code Coverage

22) How do I remove code coverage color in eclipse?

Go to Windows Menu bar > Show View > Other > Type coverage and open it. Click on Coverage. To clear highlightings, click on X or XX icon as per convenience.

23) Why is my Java code highlighted green?

Source Code Annotation

Source lines corresponding to compiled Java instructions get the following color code: green for fully covered lines, yellow for partly covered lines and. red for lines that have not been executed at all.

24) How do I highlight selected text in Eclipse?

Glance does not work anymore, but in current Eclipse Versions (Eclipse 2020) you can highlight any word by selecting the word and pressing CTRL+F.

25) How do I run test coverage in Eclipse?

To use it, you can either right-click on a class and then find and click Code Coverage > Run As, or you can just hit the Run As Code Coverage button that looks like the regular Run button (shown here): In the screen shot below, the colors are fairly self-explanatory.

26) What is Eclipse coverage?

Eclipse can check your code coverage when it runs your JUnit testing class. This means that it can show you what statements were executed in at least one test case and what ones weren’t. For an if-statement, it will tell you whether there was a test case for the condition to be false and another for it to be true.

27) What does yellow mean in code coverage?

Green means that this line of code has been executed by the tests and are “covered.” Yellow indicates a segment of code that has multiple branches and that not all the branches in code have been reached (i.e. an if statement). Red indicates that this line of code has not been reached at all and as such is not covered.

28) What is EclEmma?

EclEmma is a free Java code coverage tool for Eclipse, available under the Eclipse Public License. It brings code coverage analysis directly into the Eclipse workbench: Fast develop/test cycle: Launches from within the workbench like JUnit test runs can directly be analyzed for code coverage.

29) Does cobertura support java8?

cobertura-maven-plugin does not support Java 1.8 properly #21.

30) What is code coverage in C#?

Code coverage is a measurement of the amount of code that is run by unit tests – either lines, branches, or methods. … Coverlet is an open source project on GitHub that provides a cross-platform code coverage framework for C#.

31) What is cobertura format?

Cobertura is a free Java tool that calculates the percentage of code accessed by tests. It can be used to identify which parts of your Java program are lacking test coverage. It is based on jcoverage.

32) Which is the target location where cobertura coverage XML data will be generated?

Cobertura always uses default value target/site/coverage. xml path when running Sonar Scanner. Which Sonar property should be used to specify multiple cobertura coverage.

33) Which plugins can be used for test coverage in Jenkins?

Supported Coverage Formats
JaCoCo.
Istanbul – Cobertura Reporter.
Cobertura.

34) What is coverage criteria in software testing?

A coverage criterion is a rule or collection of rules that impose test requirements on a test set [Ammann, Offutt]. The coverage criterion describes test requirements completely and unambiguously.

35) How do I get Jenkins code coverage?

If you click on the Coverage Report icon, you will see code coverage for each package in your application, and even drill down to see the code coverage (or lack thereof) for an individual class (see Figure 2.31, “Jenkins lets you display code coverage metrics for packages and classes”).

36) How do you install JaCoCo?

How to setup JaCoCo with Maven?
Generate the project. Navigate to https://start.spring.io/ to generate a project with an appropriate version of build tool (maven), language (Java), the default version of spring. …
Import project into IDE (i.e., Eclipse) …
Add JaCoCo plugin to the pom. …
Generate code coverage report.

37) Which is the best code coverage tool for Java?

Open Source Code Coverage Tools:

Cobertura. @schristou88.
CodeCover. CodeCover is an open source glass-box testing tool for Java and COBOL.
Coverage.py. @nedbat.
EMMA. Emma is one of the oldest and most popular of the code coverage tools.
Gretel. @uoregon. …
Hansel.
JaCoCo.
JCov.

38) What is instrumentation in JaCoCo?

JaCoCo uses class file instrumentation to record execution coverage data. Class files are instrumented on-the-fly using a so called Java agent. This mechanism allows in-memory pre-processing of all class files during class loading independent of the application framework.

39) What is maven PMD plugin?

The PMD Plugin allows you to automatically run the PMD code analysis tool on your project’s source code and generate a site report with its results. It also supports the separate Copy/Paste Detector tool (or CPD) distributed with PMD.

40) How do I get my JaCoCo code coverage report?

To get code coverage reports in a Maven project, we first need to set up the JaCoCo Maven plugin for that project. By integrating the JaCoCo plugin, the results of the code coverage analysis can be reviewed as an HTML report. The current version of the JaCoCo-Maven plugin can be downloaded from the MVN Repository.

41) How does JaCoCo measure coverage?

It measures line and branch coverage based on the code covered by running unit test cases and provides a visual report, including highlighted lines of code and the total percentage of code executed in each method. From this analysis the developer can assess the code that has not been adequately tested.

42) What is true about Emma code coverage tool?

EMMA is an open-source toolkit for measuring and reporting Java code coverage. EMMA distinguishes itself from other tools by going after a unique feature combination: support for large-scale enterprise software development while keeping individual developer’s work fast and iterative.

43) How do I increase line coverage in JUnit?

4 Steps to Improve Your Test Coverage
What is Test Coverage? Test coverage measures how much of your application you test. …

1 Create a Plan and Set a Goal. …

2 Increase Code Coverage. …

3 Enhance Test Automation. …

4 Test on a Larger Scale. …

Bonus: Increase Test Coverage by Running Tests with a Cloud Test Service.

44) What is run with coverage IntelliJ?

Run with coverage

In IntelliJ IDEA, you can create multiple run/debug configurations and specify coverage options for each of them depending on your needs.

45) How do I see coverage in Intellij?

Coverage in the Coverage tool window

If you want to reopen the Coverage tool window, select Run | Show Code Coverage Data from the main menu, or press Ctrl+Alt+F6 . The report shows the percentage of the code that has been executed or covered by tests. You can see the coverage result for classes, methods, and lines.

46) What is good test coverage?

Summary. Code coverage of 70-80% is a reasonable goal for system test of most projects with most coverage metrics. Use a higher goal for projects specifically organized for high testability or that have high failure costs. Minimum code coverage for unit testing can be 10-20% higher than for system testing.

47) How do you write test cases for code coverage?

You simply take:
(A) the total lines of code in the piece of software you are testing, and.
(B) the number of lines of code all test cases currently execute, and.
Find (B divided by A) multiplied by 100 – this will be your test coverage %.

48) What are the different types of code coverage?

Following are the types of code coverage Analysis:

Statement coverage and Block coverage.
Function coverage.
Function call coverage.
Branch coverage.
Modified condition/decision coverage.

49) What is missed instructions in JaCoCo report?

Instructions (C0 Coverage)

Instruction coverage provides information about the amount of code that has been executed or missed. This metric is completely independent from source formatting and always available, even in absence of debug information in the class files.

50) What is LCOV report?

LCOV is a graphical tool for GCC’s coverage testing with gcov. It creates HTML pages containing the source code annotated with coverage information by collecting gcov data from multiple source files. LCOV supports “Lines coverage” and “Functions coverage” measurement.

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