Should black box or white box testing be the emphasis for testers

Question

Which type of testing would you say should be the emphasis  for testers QAs   and why   A quick set of definitions from wikipedia   Black box testing    takes an external perspective of the test object to derive test cases  These tests can be functional or non-functional  though usually functional  The test designer selects valid and invalid input and determines the correct output  There is no knowledge of the test object s internal structure    White box testing    uses an internal perspective of the system to design test cases based on internal structure  It requires programming skills to identify all paths through the software  The tester chooses test case inputs to exercise paths through the code and determines the appropriate outputs  In electrical hardware testing  every node in a circuit may be probed and measured  an example is in-circuit testing  ICT     Just to clarify a bit more  I realize that both are important  but  usually  they are separate between dev and QA      Is internal knowledge important for the tester QA   I ve heard arguments that testing with this knowledge in mind enables them to better test for problems  but I ve also heard arguments that this knowledge can distract from functional needs and promote  testing to the code  rather than to the intended solution

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QA should focus on Black box testing  The main goal of QA is to test what the system does  do features meet requirements     not how it does it   Anyway it should be hard for QA to do white box testing as most of QA guys aren t tech guys  so they usually test features through the UI  like users    A step further  I think developpers too should focus on Black box testing  I disagree with this widespread association between Unit testing and White box testing but it may be just a question a vocabulary scale  At the scale of a Unit test  the System Under Test is a class method which has contract  through its signature  and the important point is to test what it does  not how  Moreover White box testing implies you know how the method will fill its contract  that seems incompatile with TDD to me   IMHO if your SUT is so complex that you need to do white box testing  it s usually time for refactoring

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Black box testing should be the emphasis for testers QA  White box testing should be the emphasis for developers  i e  unit tests   The other folks who answered this question seemed to have interpreted the question as Which is more important  white box testing or black box testing  I  too  believe that they are both important but you might want to check out this IEEE article which claims that white box testing is more important

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It s a bit of an open door  but in the end both are about equally important   What s worse    software that does what it needs to do  but internally has problems  software that is supposed to work if you look at the sources  but doesn t    My answer  Neither is totally acceptable  but software cannot be proven to be 100  bugfree  So  you re going to have to make some trade-offs  Option two is more directly noticable to clients  so you re going to get problems with that sooner  On the long run  option one is going to be problematic

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Both  has been stated above  and is the obvious answer   but IMO  white box testing goes far beyond developer unit testing  althoughI suppose it could depend on where you draw the line between white and black   For example  code coverage analysis is a common white box approach - i e  run some scenarios or tests  and examine the results looking for holes in testing  Even if unit tests have 100  cc  measuring cc on common user scenarios can reveal code that may potentially need even more testing   Another place where white box testing helps is examining data types  constants and other information to look for boundaries  special values  etc  For example  if an application has an input that takes a numeric input  a bb only approach could require the tester to  guess  at what values would be good for testing  whereas a wb approach may reveal that all values between 1-256 are treated one way  while larger values are treated another way   and perhaps the number 42 has yet another code path   So  to answer the original question - both bb and wb are essential for good testing

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Usually the white-box testing is not possible for testers  Thus the only viable answer for testers is to emphasize black-box approach   However  with aspect-oriented-programming and design-by-contract methodology  when the testing goals are programmed into the target code as contracts  seen from the static view of a program   and or when the testing temporal logic is programmed into the code as cross-cuts  dynamic view of the test logic   white-box testing would become not only possible but also a preferred take for testers  Given that said  it will need be an expertise-demanding take  the testers need to be not only good testers  but also good programmers or more than good programmers

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I only partially agree with the top rated answer for this question  Which type of testing would you say should be the emphasis  for testers QAs   and why    I agree that   Black box testing should be the emphasis for testers QA   I agree that White box testing should be the emphasis for developers  but I don t agree that White Box testing is just unit tests    I agree with the definition here which states that White Box Testing method is applicable to the following levels of software testing    Unit Testing  For testing paths within a unit  Integration Testing For testing paths between units System Testing  For testing paths between subsystems

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Usually the white-box testing is not possible for testers  Thus the only viable answer for testers is to emphasize black-box approach   However  with aspect-oriented-programming and design-by-contract methodology  when the testing goals are programmed into the target code as contracts  seen from the static view of a program   and or when the testing temporal logic is programmed into the code as cross-cuts  dynamic view of the test logic   white-box testing would become not only possible but also a preferred take for testers  Given that said  it will need be an expertise-demanding take  the testers need to be not only good testers  but also good programmers or more than good programmers

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What constitutes   internal knowledge    Does knowing that such-and-such algorithm was used to solve a problem qualify or does the tester have to see every line of code for it to be  internal    I think in any test case  there should be expected results given by the specification used and not determined by how the tester decides to interpret the specification as this can lead to issues where each thinks they are right and blaming the other for the problem

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I only partially agree with the top rated answer for this question  Which type of testing would you say should be the emphasis  for testers QAs   and why    I agree that   Black box testing should be the emphasis for testers QA   I agree that White box testing should be the emphasis for developers  but I don t agree that White Box testing is just unit tests    I agree with the definition here which states that White Box Testing method is applicable to the following levels of software testing    Unit Testing  For testing paths within a unit  Integration Testing For testing paths between units System Testing  For testing paths between subsystems

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Black box testing should be the emphasis for testers QA  White box testing should be the emphasis for developers  i e  unit tests   The other folks who answered this question seemed to have interpreted the question as Which is more important  white box testing or black box testing  I  too  believe that they are both important but you might want to check out this IEEE article which claims that white box testing is more important

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White Box Testing equals Software Unit Test  The developer or a development level tester  e g  another developer  ensures that the code he has written is working properly according to the detailed level requirements before integrating it in the system   Black Box Testing equals Integration Testing  The tester ensures that the system works according to the requirements on a functional level    Both test approaches are equally important in my opinion    A thorough unit test will catch defects in the development stage and not after the software has been integrated into the system  A system level black box test will ensure all software modules behave correctly when integrated together  A unit test in the development stage would not catch these defects since modules are usually developed independent from each other

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Black Box Testing   Black Box testing is just observation no need Internal Knowledge or structure of software product  just putting valid and Invalid data input and expecting the correct result  here tester find the defect but unable to Find the Location of defect black box testing done in all testing level   Black box testing tecniques are  1  Equivalance partition 2  Boundary Value Analysis 3  Decision table 4  State Transition Diagram 4  Use case diagram  White Box Testing  White box is testing it requires the knowledge of internal logic and structure of software product  here we will check the loop  condition and  branch  here we find not only the  defect  but also and location of defect   White box Testing Techniques  1  Statement Coverage 2  Decision Coverage 3  Branch Coverage 4  Path Coverage

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What constitutes   internal knowledge    Does knowing that such-and-such algorithm was used to solve a problem qualify or does the tester have to see every line of code for it to be  internal    I think in any test case  there should be expected results given by the specification used and not determined by how the tester decides to interpret the specification as this can lead to issues where each thinks they are right and blaming the other for the problem

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Black box testing you dont see the system under test inner workings  White box testing you have full view into the system under test  Here are a few pictures showing this    Testers need to focus on the testing pyramid   You will want to understand unit tests  integration tests  and end to end tests  Each of these can be performed both with black box and white box testing  Start small and work your way up learning the different types and when to use each  remember you cant always test everything

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Black Box  1  Focuses on the functionality of the system  Focuses on the structure  Program  of the system  2  Techniques used are              Equivalence partitioning                 Boundary-value analysis               Error guessing                  Race conditions                  Cause-effect graphing              Syntax testing              State transition testing              Graph matrix    Tester can be non technical  Helps to identify the vagueness and contradiction in functional specifications  White Box  Techniques used are             Basis Path Testing            Flow Graph Notation               Control Structure Testing         Condition Testing Data Flow testing             Loop Testing   Simple Loops Nested Loops Concatenated Loops Unstructured Loops  Tester should be technical  Helps to identify the logical and coding issues

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Black box testing  Is the test at system level to check the functionality of the system  to ensure that the system performs all the functions that it was designed for  Its mainly to uncover defects found at the user point  Its better to hire a professional tester to black box your system   coz the developer usually tests with a perspective that the codes he had written is good and meets the functional requirements of the clients so he could miss out a lot of things  I don t mean to offend anybody  Whitebox is the first test that is done in the SDLC This is to uncover bugs like runtime errors and compilation errrors  It can be done either by testers or by Developer himself  But I think its always better that the person who wrote the code tests it He understands them more than another person

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Both  has been stated above  and is the obvious answer   but IMO  white box testing goes far beyond developer unit testing  althoughI suppose it could depend on where you draw the line between white and black   For example  code coverage analysis is a common white box approach - i e  run some scenarios or tests  and examine the results looking for holes in testing  Even if unit tests have 100  cc  measuring cc on common user scenarios can reveal code that may potentially need even more testing   Another place where white box testing helps is examining data types  constants and other information to look for boundaries  special values  etc  For example  if an application has an input that takes a numeric input  a bb only approach could require the tester to  guess  at what values would be good for testing  whereas a wb approach may reveal that all values between 1-256 are treated one way  while larger values are treated another way   and perhaps the number 42 has yet another code path   So  to answer the original question - both bb and wb are essential for good testing

User · Answer

Black box testing  Is the test at system level to check the functionality of the system  to ensure that the system performs all the functions that it was designed for  Its mainly to uncover defects found at the user point  Its better to hire a professional tester to black box your system   coz the developer usually tests with a perspective that the codes he had written is good and meets the functional requirements of the clients so he could miss out a lot of things  I don t mean to offend anybody  Whitebox is the first test that is done in the SDLC This is to uncover bugs like runtime errors and compilation errrors  It can be done either by testers or by Developer himself  But I think its always better that the person who wrote the code tests it He understands them more than another person

User · Answer

Both  has been stated above  and is the obvious answer   but IMO  white box testing goes far beyond developer unit testing  althoughI suppose it could depend on where you draw the line between white and black   For example  code coverage analysis is a common white box approach - i e  run some scenarios or tests  and examine the results looking for holes in testing  Even if unit tests have 100  cc  measuring cc on common user scenarios can reveal code that may potentially need even more testing   Another place where white box testing helps is examining data types  constants and other information to look for boundaries  special values  etc  For example  if an application has an input that takes a numeric input  a bb only approach could require the tester to  guess  at what values would be good for testing  whereas a wb approach may reveal that all values between 1-256 are treated one way  while larger values are treated another way   and perhaps the number 42 has yet another code path   So  to answer the original question - both bb and wb are essential for good testing

User · Answer

Black box testing  Is the test at system level to check the functionality of the system  to ensure that the system performs all the functions that it was designed for  Its mainly to uncover defects found at the user point  Its better to hire a professional tester to black box your system   coz the developer usually tests with a perspective that the codes he had written is good and meets the functional requirements of the clients so he could miss out a lot of things  I don t mean to offend anybody  Whitebox is the first test that is done in the SDLC This is to uncover bugs like runtime errors and compilation errrors  It can be done either by testers or by Developer himself  But I think its always better that the person who wrote the code tests it He understands them more than another person

User · Answer

White Box Testing equals Software Unit Test  The developer or a development level tester  e g  another developer  ensures that the code he has written is working properly according to the detailed level requirements before integrating it in the system   Black Box Testing equals Integration Testing  The tester ensures that the system works according to the requirements on a functional level    Both test approaches are equally important in my opinion    A thorough unit test will catch defects in the development stage and not after the software has been integrated into the system  A system level black box test will ensure all software modules behave correctly when integrated together  A unit test in the development stage would not catch these defects since modules are usually developed independent from each other

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Black Box Testing   Black Box testing is just observation no need Internal Knowledge or structure of software product  just putting valid and Invalid data input and expecting the correct result  here tester find the defect but unable to Find the Location of defect black box testing done in all testing level   Black box testing tecniques are  1  Equivalance partition 2  Boundary Value Analysis 3  Decision table 4  State Transition Diagram 4  Use case diagram  White Box Testing  White box is testing it requires the knowledge of internal logic and structure of software product  here we will check the loop  condition and  branch  here we find not only the  defect  but also and location of defect   White box Testing Techniques  1  Statement Coverage 2  Decision Coverage 3  Branch Coverage 4  Path Coverage

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Black Box Testing is a software testing method in which the internal structure  design  implementation of the item being tested is NOT known to the tester  White Box Testing is a software testing method in which the internal structure  design  implementation of the item being tested is known to the tester

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Simple   Blackbox testing is otherwise known as Integration testing or smoke-screen testing   This is mostly applied in a distributed environment which rely on event-driven architecture  You test a service based on another service to see all possible scenarios  Here you cannot completely forecast all possible output because each component of the SOA Enterprise app are meant to function autonomously  This can be referred to as High-Level testing  while  White box testing refers to unit-testing  where all expected scenarios and output can be effectively forecasted  i e Input and expected output This can be referred to as Low-level testing

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Both  has been stated above  and is the obvious answer   but IMO  white box testing goes far beyond developer unit testing  althoughI suppose it could depend on where you draw the line between white and black   For example  code coverage analysis is a common white box approach - i e  run some scenarios or tests  and examine the results looking for holes in testing  Even if unit tests have 100  cc  measuring cc on common user scenarios can reveal code that may potentially need even more testing   Another place where white box testing helps is examining data types  constants and other information to look for boundaries  special values  etc  For example  if an application has an input that takes a numeric input  a bb only approach could require the tester to  guess  at what values would be good for testing  whereas a wb approach may reveal that all values between 1-256 are treated one way  while larger values are treated another way   and perhaps the number 42 has yet another code path   So  to answer the original question - both bb and wb are essential for good testing

User · Answer

Black box testing should be the emphasis for testers QA  White box testing should be the emphasis for developers  i e  unit tests   The other folks who answered this question seemed to have interpreted the question as Which is more important  white box testing or black box testing  I  too  believe that they are both important but you might want to check out this IEEE article which claims that white box testing is more important

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Here is my 5 cents   As a developer  I mostly write tests for methods  in a class  as white box tests  simple because I do not want my test to break just because I change the inner works of my code    I only want to my tests to break if my method behavior changes  e g  returns a different result than before    Over the last 20 years of development  I simple got tired of doing up-to double work just because my unit tests was strongly tied to the code and I need to maintain both application code and test code    I think making decoupling code  also when you code tests  is a very good practice   Another 5 cents  I hardly never use mocking frameworks  because when I find it necessarily to mock something I prefer to decouple my code instead - and yes in many cases that is very possible  especially if you are not working in legacy code   -

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Black Box  1  Focuses on the functionality of the system  Focuses on the structure  Program  of the system  2  Techniques used are              Equivalence partitioning                 Boundary-value analysis               Error guessing                  Race conditions                  Cause-effect graphing              Syntax testing              State transition testing              Graph matrix    Tester can be non technical  Helps to identify the vagueness and contradiction in functional specifications  White Box  Techniques used are             Basis Path Testing            Flow Graph Notation               Control Structure Testing         Condition Testing Data Flow testing             Loop Testing   Simple Loops Nested Loops Concatenated Loops Unstructured Loops  Tester should be technical  Helps to identify the logical and coding issues

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In my experience most developers naturally migrate towards white box testing   Since we need to ensure that the underlying algorithm is  correct   we tend to focus more on the internals   But  as has been pointed out  both white and black box testing is important   Therefore  I prefer to have testers focus more on the Black Box tests  to cover for the fact that most developers don t really do it  and frequently aren t very good at it   That isn t to say that testers should be kept in the dark about how the system works  just that I prefer them to focus more on the problem domain and how actual users interact with the system  not whether the function SomeMethod int x  will correctly throw an exception if x is equal to 5

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Here is my 5 cents   As a developer  I mostly write tests for methods  in a class  as white box tests  simple because I do not want my test to break just because I change the inner works of my code    I only want to my tests to break if my method behavior changes  e g  returns a different result than before    Over the last 20 years of development  I simple got tired of doing up-to double work just because my unit tests was strongly tied to the code and I need to maintain both application code and test code    I think making decoupling code  also when you code tests  is a very good practice   Another 5 cents  I hardly never use mocking frameworks  because when I find it necessarily to mock something I prefer to decouple my code instead - and yes in many cases that is very possible  especially if you are not working in legacy code   -

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In my experience most developers naturally migrate towards white box testing   Since we need to ensure that the underlying algorithm is  correct   we tend to focus more on the internals   But  as has been pointed out  both white and black box testing is important   Therefore  I prefer to have testers focus more on the Black Box tests  to cover for the fact that most developers don t really do it  and frequently aren t very good at it   That isn t to say that testers should be kept in the dark about how the system works  just that I prefer them to focus more on the problem domain and how actual users interact with the system  not whether the function SomeMethod int x  will correctly throw an exception if x is equal to 5

User · Answer

Black box testing should be the emphasis for testers QA  White box testing should be the emphasis for developers  i e  unit tests   The other folks who answered this question seemed to have interpreted the question as Which is more important  white box testing or black box testing  I  too  believe that they are both important but you might want to check out this IEEE article which claims that white box testing is more important

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Black-Box testing  If the source code is not available then test data is based on the function of the software without regard to how it was implemented   -strong textExamples of black-box testing are  boundary value testing and equivalence partitioning    White-Box testing  If the source code of the system under test is available then the test data is based on the structure of this source code  -Examples of white-box testing are  path testing and data flow testing

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QA should focus on Black box testing  The main goal of QA is to test what the system does  do features meet requirements     not how it does it   Anyway it should be hard for QA to do white box testing as most of QA guys aren t tech guys  so they usually test features through the UI  like users    A step further  I think developpers too should focus on Black box testing  I disagree with this widespread association between Unit testing and White box testing but it may be just a question a vocabulary scale  At the scale of a Unit test  the System Under Test is a class method which has contract  through its signature  and the important point is to test what it does  not how  Moreover White box testing implies you know how the method will fill its contract  that seems incompatile with TDD to me   IMHO if your SUT is so complex that you need to do white box testing  it s usually time for refactoring

User · Answer

White Box Testing equals Software Unit Test  The developer or a development level tester  e g  another developer  ensures that the code he has written is working properly according to the detailed level requirements before integrating it in the system   Black Box Testing equals Integration Testing  The tester ensures that the system works according to the requirements on a functional level    Both test approaches are equally important in my opinion    A thorough unit test will catch defects in the development stage and not after the software has been integrated into the system  A system level black box test will ensure all software modules behave correctly when integrated together  A unit test in the development stage would not catch these defects since modules are usually developed independent from each other

User · Answer

Black box testing you dont see the system under test inner workings  White box testing you have full view into the system under test  Here are a few pictures showing this    Testers need to focus on the testing pyramid   You will want to understand unit tests  integration tests  and end to end tests  Each of these can be performed both with black box and white box testing  Start small and work your way up learning the different types and when to use each  remember you cant always test everything

User · Answer

What constitutes   internal knowledge    Does knowing that such-and-such algorithm was used to solve a problem qualify or does the tester have to see every line of code for it to be  internal    I think in any test case  there should be expected results given by the specification used and not determined by how the tester decides to interpret the specification as this can lead to issues where each thinks they are right and blaming the other for the problem

User · Answer

What constitutes   internal knowledge    Does knowing that such-and-such algorithm was used to solve a problem qualify or does the tester have to see every line of code for it to be  internal    I think in any test case  there should be expected results given by the specification used and not determined by how the tester decides to interpret the specification as this can lead to issues where each thinks they are right and blaming the other for the problem

User · Answer

Black box testing  Is the test at system level to check the functionality of the system  to ensure that the system performs all the functions that it was designed for  Its mainly to uncover defects found at the user point  Its better to hire a professional tester to black box your system   coz the developer usually tests with a perspective that the codes he had written is good and meets the functional requirements of the clients so he could miss out a lot of things  I don t mean to offend anybody  Whitebox is the first test that is done in the SDLC This is to uncover bugs like runtime errors and compilation errrors  It can be done either by testers or by Developer himself  But I think its always better that the person who wrote the code tests it He understands them more than another person

User · Answer

Black Box Testing is a software testing method in which the internal structure  design  implementation of the item being tested is NOT known to the tester  White Box Testing is a software testing method in which the internal structure  design  implementation of the item being tested is known to the tester

User · Answer

In my experience most developers naturally migrate towards white box testing   Since we need to ensure that the underlying algorithm is  correct   we tend to focus more on the internals   But  as has been pointed out  both white and black box testing is important   Therefore  I prefer to have testers focus more on the Black Box tests  to cover for the fact that most developers don t really do it  and frequently aren t very good at it   That isn t to say that testers should be kept in the dark about how the system works  just that I prefer them to focus more on the problem domain and how actual users interact with the system  not whether the function SomeMethod int x  will correctly throw an exception if x is equal to 5

User · Answer

White Box Testing equals Software Unit Test  The developer or a development level tester  e g  another developer  ensures that the code he has written is working properly according to the detailed level requirements before integrating it in the system   Black Box Testing equals Integration Testing  The tester ensures that the system works according to the requirements on a functional level    Both test approaches are equally important in my opinion    A thorough unit test will catch defects in the development stage and not after the software has been integrated into the system  A system level black box test will ensure all software modules behave correctly when integrated together  A unit test in the development stage would not catch these defects since modules are usually developed independent from each other

User · Answer

Simple   Blackbox testing is otherwise known as Integration testing or smoke-screen testing   This is mostly applied in a distributed environment which rely on event-driven architecture  You test a service based on another service to see all possible scenarios  Here you cannot completely forecast all possible output because each component of the SOA Enterprise app are meant to function autonomously  This can be referred to as High-Level testing  while  White box testing refers to unit-testing  where all expected scenarios and output can be effectively forecasted  i e Input and expected output This can be referred to as Low-level testing

User · Answer

It s a bit of an open door  but in the end both are about equally important   What s worse    software that does what it needs to do  but internally has problems  software that is supposed to work if you look at the sources  but doesn t    My answer  Neither is totally acceptable  but software cannot be proven to be 100  bugfree  So  you re going to have to make some trade-offs  Option two is more directly noticable to clients  so you re going to get problems with that sooner  On the long run  option one is going to be problematic

User · Answer

It s a bit of an open door  but in the end both are about equally important   What s worse    software that does what it needs to do  but internally has problems  software that is supposed to work if you look at the sources  but doesn t    My answer  Neither is totally acceptable  but software cannot be proven to be 100  bugfree  So  you re going to have to make some trade-offs  Option two is more directly noticable to clients  so you re going to get problems with that sooner  On the long run  option one is going to be problematic

User · Answer

In my experience most developers naturally migrate towards white box testing   Since we need to ensure that the underlying algorithm is  correct   we tend to focus more on the internals   But  as has been pointed out  both white and black box testing is important   Therefore  I prefer to have testers focus more on the Black Box tests  to cover for the fact that most developers don t really do it  and frequently aren t very good at it   That isn t to say that testers should be kept in the dark about how the system works  just that I prefer them to focus more on the problem domain and how actual users interact with the system  not whether the function SomeMethod int x  will correctly throw an exception if x is equal to 5

User · Answer

Black-Box testing  If the source code is not available then test data is based on the function of the software without regard to how it was implemented   -strong textExamples of black-box testing are  boundary value testing and equivalence partitioning    White-Box testing  If the source code of the system under test is available then the test data is based on the structure of this source code  -Examples of white-box testing are  path testing and data flow testing

User · Answer

It s a bit of an open door  but in the end both are about equally important   What s worse    software that does what it needs to do  but internally has problems  software that is supposed to work if you look at the sources  but doesn t    My answer  Neither is totally acceptable  but software cannot be proven to be 100  bugfree  So  you re going to have to make some trade-offs  Option two is more directly noticable to clients  so you re going to get problems with that sooner  On the long run  option one is going to be problematic

[testing] Should black box or white box testing be the emphasis for testers?

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