What is code coverage and how do YOU measure it

Question

What is code coverage and how do YOU measure it   I was asked this question regarding our automating testing code coverage  It seems to be that  outside of automated tools  it is more art than science  Are there any real-world examples of how to use code coverage

User · Answer

Code coverage basically tells you how much of your code is covered under tests. For example, if you have 90% code coverage, it means 10% of the code is not covered under tests.

I know you might be thinking that if 90% of the code is covered, it's good enough, but you have to look from a different angle. What is stopping you from getting 100% code coverage?

A good example will be this:

if(customer.IsOldCustomer()) 
{
}
else 
{
}

Now, in the code above, there are two paths/branches. If you are always hitting the "YES" branch, you are not covering the "else" part and it will be shown in the Code Coverage results. This is good because now you know that what is not covered and you can write a test to cover the "else" part. If there was no code coverage, you are just sitting on a time bomb, waiting to explode.

NCover is a good tool to measure code coverage.

User · Answer

Code coverage is a measurement of how many lines blocks arcs of your code are executed while the automated tests are running   Code coverage is collected by using a specialized tool to instrument the binaries to add tracing calls and run a full set of automated tests against the instrumented product  A good tool will give you not only the percentage of the code that is executed  but also will allow you to drill into the data and see exactly which lines of code were executed during a particular test   Our team uses Magellan - an in-house set of code coverage tools  If you are a  NET shop  Visual Studio has integrated tools to collect code coverage  You can also roll some custom tools  like this article describes   If you are a C   shop  Intel has some tools that run for Windows and Linux  though I haven t used them  I ve also heard there s the gcov tool for GCC  but I don t know anything about it and can t give you a link   As to how we use it - code coverage is one of our exit criteria for each milestone  We have actually three code coverage metrics - coverage from unit tests  from the development team   scenario tests  from the test team  and combined coverage   BTW  while code coverage is a good metric of how much testing you are doing  it is not necessarily a good metric of how well you are testing your product  There are other metrics you should use along with code coverage to ensure the quality

User · Answer

Code coverage is a measurement of how many lines blocks arcs of your code are executed while the automated tests are running   Code coverage is collected by using a specialized tool to instrument the binaries to add tracing calls and run a full set of automated tests against the instrumented product  A good tool will give you not only the percentage of the code that is executed  but also will allow you to drill into the data and see exactly which lines of code were executed during a particular test   Our team uses Magellan - an in-house set of code coverage tools  If you are a  NET shop  Visual Studio has integrated tools to collect code coverage  You can also roll some custom tools  like this article describes   If you are a C   shop  Intel has some tools that run for Windows and Linux  though I haven t used them  I ve also heard there s the gcov tool for GCC  but I don t know anything about it and can t give you a link   As to how we use it - code coverage is one of our exit criteria for each milestone  We have actually three code coverage metrics - coverage from unit tests  from the development team   scenario tests  from the test team  and combined coverage   BTW  while code coverage is a good metric of how much testing you are doing  it is not necessarily a good metric of how well you are testing your product  There are other metrics you should use along with code coverage to ensure the quality

User · Answer

Code coverage has been explained well in the previous answers  So this is more of an answer to the second part of the question   We ve used three tools to determine code coverage    JTest - a proprietary tool built over JUnit   It generates unit tests as well   Cobertura - an open source code coverage tool that can easily be coupled with JUnit tests to generate reports  Emma  - another - this one we ve used for a slightly different  purpose than unit testing  It has been used to generate coverage reports when the web application is accessed by end-users  This coupled with web testing tools  example  Canoo  can give you very useful coverage reports which tell you how much code is covered during typical end user usage    We use these tools to   Review that developers have written good unit tests Ensure that all code is traversed during black-box testing

User · Answer

Just remember  having  100  code-coverage  doesn t mean everything is tested completely - while it means every line of code is tested  it doesn t mean they are tested under every  common  situation    I would use code-coverage to highlight bits of code that I should probably write tests for  For example  if whatever code-coverage tool shows myImportantFunction   isn t executed while running my current unit-tests  they should probably be improved   Basically  100  code-coverage doesn t mean your code is perfect  Use it as a guide to write more comprehensive  unit- tests

User · Answer

Code coverage is a measurement of how many lines blocks arcs of your code are executed while the automated tests are running   Code coverage is collected by using a specialized tool to instrument the binaries to add tracing calls and run a full set of automated tests against the instrumented product  A good tool will give you not only the percentage of the code that is executed  but also will allow you to drill into the data and see exactly which lines of code were executed during a particular test   Our team uses Magellan - an in-house set of code coverage tools  If you are a  NET shop  Visual Studio has integrated tools to collect code coverage  You can also roll some custom tools  like this article describes   If you are a C   shop  Intel has some tools that run for Windows and Linux  though I haven t used them  I ve also heard there s the gcov tool for GCC  but I don t know anything about it and can t give you a link   As to how we use it - code coverage is one of our exit criteria for each milestone  We have actually three code coverage metrics - coverage from unit tests  from the development team   scenario tests  from the test team  and combined coverage   BTW  while code coverage is a good metric of how much testing you are doing  it is not necessarily a good metric of how well you are testing your product  There are other metrics you should use along with code coverage to ensure the quality

User · Answer

Code coverage is a measurement of how many lines blocks arcs of your code are executed while the automated tests are running   Code coverage is collected by using a specialized tool to instrument the binaries to add tracing calls and run a full set of automated tests against the instrumented product  A good tool will give you not only the percentage of the code that is executed  but also will allow you to drill into the data and see exactly which lines of code were executed during a particular test   Our team uses Magellan - an in-house set of code coverage tools  If you are a  NET shop  Visual Studio has integrated tools to collect code coverage  You can also roll some custom tools  like this article describes   If you are a C   shop  Intel has some tools that run for Windows and Linux  though I haven t used them  I ve also heard there s the gcov tool for GCC  but I don t know anything about it and can t give you a link   As to how we use it - code coverage is one of our exit criteria for each milestone  We have actually three code coverage metrics - coverage from unit tests  from the development team   scenario tests  from the test team  and combined coverage   BTW  while code coverage is a good metric of how much testing you are doing  it is not necessarily a good metric of how well you are testing your product  There are other metrics you should use along with code coverage to ensure the quality

User · Answer

For PHP you should take a look at the Github from Sebastian Bergmann      Provides collection  processing  and rendering functionality for PHP code coverage information    https   github com sebastianbergmann php-code-coverage

User · Answer

For Perl there s the excellent Devel  Cover module which I regularly use on my modules    If the build and installation is managed by Module  Build you can simply run   Build testcover to get a nice HTML site that tells you the coverage per sub  line and condition  with nice colors making it easy to see which code path has not been covered

User · Answer

For Perl there s the excellent Devel  Cover module which I regularly use on my modules    If the build and installation is managed by Module  Build you can simply run   Build testcover to get a nice HTML site that tells you the coverage per sub  line and condition  with nice colors making it easy to see which code path has not been covered

User · Answer

Code coverage is simply a measure of the code that is tested  There are a variety of coverage criteria that can be measured  but typically it is the various paths  conditions  functions  and statements within a program that makeup the total coverage  The code coverage metric is the just a percentage of tests that execute each of these coverage criteria   As far as how I go about tracking unit test coverage on my projects  I use static code analysis tools to keep track

User · Answer

Code coverage has been explained well in the previous answers  So this is more of an answer to the second part of the question   We ve used three tools to determine code coverage    JTest - a proprietary tool built over JUnit   It generates unit tests as well   Cobertura - an open source code coverage tool that can easily be coupled with JUnit tests to generate reports  Emma  - another - this one we ve used for a slightly different  purpose than unit testing  It has been used to generate coverage reports when the web application is accessed by end-users  This coupled with web testing tools  example  Canoo  can give you very useful coverage reports which tell you how much code is covered during typical end user usage    We use these tools to   Review that developers have written good unit tests Ensure that all code is traversed during black-box testing

User · Answer

For Perl there s the excellent Devel  Cover module which I regularly use on my modules    If the build and installation is managed by Module  Build you can simply run   Build testcover to get a nice HTML site that tells you the coverage per sub  line and condition  with nice colors making it easy to see which code path has not been covered

User · Answer

For Perl there s the excellent Devel  Cover module which I regularly use on my modules    If the build and installation is managed by Module  Build you can simply run   Build testcover to get a nice HTML site that tells you the coverage per sub  line and condition  with nice colors making it easy to see which code path has not been covered

User · Answer

In the previous answers Code coverage has been explained well   I am just adding some knowledge related to tools if your are working on iOS and OSX platforms  Xcode provides the facility to test and monitor code coverage   Reference Links   https   developer apple com library archive documentation DeveloperTools Conceptual testing with xcode chapters 07-code coverage html  https   medium com zendesk-engineering code-coverage-and-xcode-6b2fb8756a51  Both are helpful links for learning and exploring code coverage with Xcode

User · Answer

Code coverage has been explained well in the previous answers  So this is more of an answer to the second part of the question   We ve used three tools to determine code coverage    JTest - a proprietary tool built over JUnit   It generates unit tests as well   Cobertura - an open source code coverage tool that can easily be coupled with JUnit tests to generate reports  Emma  - another - this one we ve used for a slightly different  purpose than unit testing  It has been used to generate coverage reports when the web application is accessed by end-users  This coupled with web testing tools  example  Canoo  can give you very useful coverage reports which tell you how much code is covered during typical end user usage    We use these tools to   Review that developers have written good unit tests Ensure that all code is traversed during black-box testing

User · Answer

For PHP you should take a look at the Github from Sebastian Bergmann      Provides collection  processing  and rendering functionality for PHP code coverage information    https   github com sebastianbergmann php-code-coverage

User · Answer

In the previous answers Code coverage has been explained well   I am just adding some knowledge related to tools if your are working on iOS and OSX platforms  Xcode provides the facility to test and monitor code coverage   Reference Links   https   developer apple com library archive documentation DeveloperTools Conceptual testing with xcode chapters 07-code coverage html  https   medium com zendesk-engineering code-coverage-and-xcode-6b2fb8756a51  Both are helpful links for learning and exploring code coverage with Xcode

User · Answer

Complementing a few points to many of the previous answers   Code coverage means  how well your test set is covering your source code  i e  to what extent is the source code covered by the set of test cases   As mentioned in above answers  there are various coverage criteria  like paths  conditions  functions  statements  etc  But additional criteria to be covered are   Condition coverage  All boolean expressions to be evaluated for true and false  Decision coverage  Not just boolean expressions to be evaluated for true and false once  but to cover all subsequent if-elseif-else body  Loop Coverage  means  has every possible loop been executed one time  more than once and zero time  Also  if we have assumption on max limit  then  if feasible  test maximum limit times and  one more than maximum limit times  Entry and Exit Coverage  Test for all possible call and its return value  Parameter Value Coverage  PVC   To check if all possible values for a parameter are tested  For example  a string could be any of these commonly  a  null  b  empty  c  whitespace  space  tabs  new line   d  valid string  e  invalid string  f  single-byte string  g  double-byte string  Failure to test each possible parameter value may leave a bug  Testing only one of these could result in 100  code coverage as each line is covered  but as only one of seven options are tested  means  only 14 2  coverage of parameter value  Inheritance Coverage  In case of object oriented source  when returning a derived object referred by base class  coverage to evaluate  if sibling object is returned  should be tested    Note  Static code analysis will find if there are any unreachable code or hanging code  i e  code not covered by any other function call  And also other static coverage  Even if static code analysis reports that 100  code is covered  it does not give reports about your testing set if all possible code coverage is tested

User · Answer

Code coverage has been explained well in the previous answers  So this is more of an answer to the second part of the question   We ve used three tools to determine code coverage    JTest - a proprietary tool built over JUnit   It generates unit tests as well   Cobertura - an open source code coverage tool that can easily be coupled with JUnit tests to generate reports  Emma  - another - this one we ve used for a slightly different  purpose than unit testing  It has been used to generate coverage reports when the web application is accessed by end-users  This coupled with web testing tools  example  Canoo  can give you very useful coverage reports which tell you how much code is covered during typical end user usage    We use these tools to   Review that developers have written good unit tests Ensure that all code is traversed during black-box testing

User · Answer

Complementing a few points to many of the previous answers   Code coverage means  how well your test set is covering your source code  i e  to what extent is the source code covered by the set of test cases   As mentioned in above answers  there are various coverage criteria  like paths  conditions  functions  statements  etc  But additional criteria to be covered are   Condition coverage  All boolean expressions to be evaluated for true and false  Decision coverage  Not just boolean expressions to be evaluated for true and false once  but to cover all subsequent if-elseif-else body  Loop Coverage  means  has every possible loop been executed one time  more than once and zero time  Also  if we have assumption on max limit  then  if feasible  test maximum limit times and  one more than maximum limit times  Entry and Exit Coverage  Test for all possible call and its return value  Parameter Value Coverage  PVC   To check if all possible values for a parameter are tested  For example  a string could be any of these commonly  a  null  b  empty  c  whitespace  space  tabs  new line   d  valid string  e  invalid string  f  single-byte string  g  double-byte string  Failure to test each possible parameter value may leave a bug  Testing only one of these could result in 100  code coverage as each line is covered  but as only one of seven options are tested  means  only 14 2  coverage of parameter value  Inheritance Coverage  In case of object oriented source  when returning a derived object referred by base class  coverage to evaluate  if sibling object is returned  should be tested    Note  Static code analysis will find if there are any unreachable code or hanging code  i e  code not covered by any other function call  And also other static coverage  Even if static code analysis reports that 100  code is covered  it does not give reports about your testing set if all possible code coverage is tested

User · Answer

Code coverage is simply a measure of the code that is tested  There are a variety of coverage criteria that can be measured  but typically it is the various paths  conditions  functions  and statements within a program that makeup the total coverage  The code coverage metric is the just a percentage of tests that execute each of these coverage criteria   As far as how I go about tracking unit test coverage on my projects  I use static code analysis tools to keep track

User · Answer

Code coverage basically tells you how much of your code is covered under tests. For example, if you have 90% code coverage, it means 10% of the code is not covered under tests.

I know you might be thinking that if 90% of the code is covered, it's good enough, but you have to look from a different angle. What is stopping you from getting 100% code coverage?

A good example will be this:

if(customer.IsOldCustomer()) 
{
}
else 
{
}

Now, in the code above, there are two paths/branches. If you are always hitting the "YES" branch, you are not covering the "else" part and it will be shown in the Code Coverage results. This is good because now you know that what is not covered and you can write a test to cover the "else" part. If there was no code coverage, you are just sitting on a time bomb, waiting to explode.

NCover is a good tool to measure code coverage.

User · Answer

Just remember  having  100  code-coverage  doesn t mean everything is tested completely - while it means every line of code is tested  it doesn t mean they are tested under every  common  situation    I would use code-coverage to highlight bits of code that I should probably write tests for  For example  if whatever code-coverage tool shows myImportantFunction   isn t executed while running my current unit-tests  they should probably be improved   Basically  100  code-coverage doesn t mean your code is perfect  Use it as a guide to write more comprehensive  unit- tests

User · Answer

Code coverage basically tells you how much of your code is covered under tests. For example, if you have 90% code coverage, it means 10% of the code is not covered under tests.

I know you might be thinking that if 90% of the code is covered, it's good enough, but you have to look from a different angle. What is stopping you from getting 100% code coverage?

A good example will be this:

if(customer.IsOldCustomer()) 
{
}
else 
{
}

Now, in the code above, there are two paths/branches. If you are always hitting the "YES" branch, you are not covering the "else" part and it will be shown in the Code Coverage results. This is good because now you know that what is not covered and you can write a test to cover the "else" part. If there was no code coverage, you are just sitting on a time bomb, waiting to explode.

NCover is a good tool to measure code coverage.

User · Answer

Just remember  having  100  code-coverage  doesn t mean everything is tested completely - while it means every line of code is tested  it doesn t mean they are tested under every  common  situation    I would use code-coverage to highlight bits of code that I should probably write tests for  For example  if whatever code-coverage tool shows myImportantFunction   isn t executed while running my current unit-tests  they should probably be improved   Basically  100  code-coverage doesn t mean your code is perfect  Use it as a guide to write more comprehensive  unit- tests

User · Answer

Just remember  having  100  code-coverage  doesn t mean everything is tested completely - while it means every line of code is tested  it doesn t mean they are tested under every  common  situation    I would use code-coverage to highlight bits of code that I should probably write tests for  For example  if whatever code-coverage tool shows myImportantFunction   isn t executed while running my current unit-tests  they should probably be improved   Basically  100  code-coverage doesn t mean your code is perfect  Use it as a guide to write more comprehensive  unit- tests

User · Answer

Code coverage is simply a measure of the code that is tested  There are a variety of coverage criteria that can be measured  but typically it is the various paths  conditions  functions  and statements within a program that makeup the total coverage  The code coverage metric is the just a percentage of tests that execute each of these coverage criteria   As far as how I go about tracking unit test coverage on my projects  I use static code analysis tools to keep track

User · Answer

Code coverage is simply a measure of the code that is tested  There are a variety of coverage criteria that can be measured  but typically it is the various paths  conditions  functions  and statements within a program that makeup the total coverage  The code coverage metric is the just a percentage of tests that execute each of these coverage criteria   As far as how I go about tracking unit test coverage on my projects  I use static code analysis tools to keep track

User · Answer

Code coverage basically tells you how much of your code is covered under tests. For example, if you have 90% code coverage, it means 10% of the code is not covered under tests.

I know you might be thinking that if 90% of the code is covered, it's good enough, but you have to look from a different angle. What is stopping you from getting 100% code coverage?

A good example will be this:

if(customer.IsOldCustomer()) 
{
}
else 
{
}

Now, in the code above, there are two paths/branches. If you are always hitting the "YES" branch, you are not covering the "else" part and it will be shown in the Code Coverage results. This is good because now you know that what is not covered and you can write a test to cover the "else" part. If there was no code coverage, you are just sitting on a time bomb, waiting to explode.

NCover is a good tool to measure code coverage.

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