About test cases

Test column

• The basic concept of software testing
• About software testing
• As a tester , These basic knowledge are essential

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One . The basic elements of test cases

1. What is a test case

This has already been said before , For details, see The basic concept of software testing This blog , Here is a brief introduction : A test case is a set of sets initiated to the system under test , Include Test environment , testing procedure , Test data , Expected results !

2. Why do software testers write test cases ?

Here are several reasons :

• The test case is Basis for test execution ;
• The test case You can reuse , There is no need to rewrite it when doing regression testing ;
• Test cases can Measure demand coverage ;
• Future generations can learn from ;
• The manual test case is The basis of automated testing

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Two . Design method of test case

1. Design test cases based on requirements

Requirements are the basis for testers to test , Testers analyze requirements , Verify the rationality and correctness of the requirements , No ambiguity , Extract test items from requirements , Further subdivide according to the test items , Extract the test data , To write test cases , There can be the following considerations :

• from The interface starts to test ( accord with UI Design draft );
• Verify the function of the software , Wear business-related functions for testing ( Relevant functions ), Instead of focusing on an isolated function ;
• A different function Input Different from the corresponding Output ;
• Interaction between functions ( The interaction between different roles in the same system is similar to that between sellers and buyers );
• Abnormal function test ;
• Functions used Verification of Algorithm ( This needs to look at the code level );
• from Ease of use , Compatibility performance Wait for several aspects to consider .
• Non functional testing : Non functional testing is to make some restrictions on the functions of the software itself , Non functional tests mainly include Ease of use , Compatibility , performance , Security , Portability , reliability , Maintainability ; In addition, different applications have different requirements for these non functionality :
  Suppose it's client-side software , Be similar to Word, For performance , Security requirements are generally not too high , For compatibility , Portability , The stability will be relatively high ;
  Suppose it's software for the enterprise , Similar to flying book , Its compatibility with , Performance requirements are not very high , But for functionality , Reliability requirements will be very high ;
  Suppose it is large-scale commercial software , Similar to wechat ,QQ, Its impact on performance , Compatibility , reliability , Portability , Security requirements will be very high !
  So for different software , Its non functionality is also different !

2. Methods of designing test cases

2.1. Equivalence class

We can input ( Output is considered only under special circumstances ), Divide the input into several equivalent classes , Then select one or more test cases from each equivalent class to test , If this test case passes , Let's say that the equivalence class represented by this test case passes ! In this way , We can solve the situation that the test cases cannot be exhausted !
In addition, equivalence classes can also be divided into effective equivalence classes ( A data set that meets the data specifications of user needs ) And invalid equivalence classes ( Data sets that do not meet the data specifications of user needs ), And if you test , Both valid equivalence classes and invalid equivalence classes need to be tested , Guarantee " Be on the safe side "!

Do a simple exercise : Suppose a user name is required 6-15 Its character type is A-Z Case insensitive :
Effective equivalence class :6~15 Upper case characters ,6 ~15 Lowercase letters .6 ~ 15 Mixed case
Invalid equivalence class : Less than 6 Characters , Greater than 15 Characters ,6 ~ 15 Other characters , Numbers + Letter , Numbers + Special characters , Special characters + Letter

2.2. The boundary value

in the light of The boundary between input and output is used to design test cases , The assumption is 6 ~ 15 position ,5 unqualified ,6,7 qualified ,14,15 qualified ,16 unqualified ; Therefore, the boundary value is not only the value on the boundary of the region , And take the values on both sides of the boundary , In addition, boundary values and equivalence classes are combined to design for testing !

2.3. Wrong guess

This method is mainly According to the tester's experience , And the accumulation of knowledge , guess Is there a problem with a certain function , Write targeted test cases , This is a detective test , More targeted , Rely more on the personal level of the tester , For example, the space problem in the search box , You need testers to do guessing tests !

2.4. Scene method

Many different scenarios of software , Is based on the triggering of different events , Triggering of different events , Lead the scene to different event flows , and Different function points are strung together to form a scene , Different function points have different outputs , Different outputs lead to different test scenarios , Here we can simulate a ATM Withdrawal scenario : Card insertion – Input password – Enter the withdrawal amount – Withdraw money – Withdraw card , Then there can be many test cases according to each function :

• Card insertion : Insert the wrong card ( Various other cards , Non bank card ), The card is inserted backwards , Non bank card , The magnetic stripe of the bank card cannot be recognized , The card is damaged , Card number is frozen , The account is locked , The network is not good , Can't recognize …
• Input password : Confirm directly without entering the password , Enter the wrong password , Enter the wrong password , The password was entered incorrectly more than three times , The account , Whether the password input box supports deleting input , Test whether the password is encrypted …
• Enter the withdrawal amount : Enter the amount of money less than the card balance , Enter the amount of money greater than the card balance , Enter the amount of money equal to the card balance , Do not enter whether the withdrawal button can be executed …
• Withdraw money : Enter the amount of money less than or equal to the card balance, and the withdrawal is successful , Enter the amount of money greater than the card balance, and the withdrawal fails and the balance is insufficient , Exceed the upper limit of daily withdrawal balance , Exceed the maximum number of withdrawals per day …
• Withdraw card : Return the card normally after withdrawing money , Operation timeout swallowing card …
• ATM machine :ATM Everything is all right ,ATM The machine is abnormal (ATM Lack of balance ,ATM The machine is powered off , Broken net , Hardware failure , The software system crashed ) Unable to perform the above functions , Abnormal situation ATM Whether the machine supports transaction rollback …

The above are just some simple test points , Not specific test cases , If test cases , Need to be more specific , And this is the specific use of the scene method !

2.5. Cause and effect diagram

Cause and effect diagram is a kind of Logic diagram , Identity , And , or , Not , Use cause and effect diagram to design test cases , It's called cause and effect diagram , Its usage scenarios : When we have a lot of input , Different inputs or different combinations of inputs have different outputs , At this point, we can use the cause and effect diagram method to design test cases , Let's take a look at various cause and effect diagrams :

• Identity :
  

• And : When multiple different inputs are true , The output is true ( It is similar to having a car and a house -> Marriage is not allowed in other situations , But other situations also need to be considered ):
  

• or : Multiple inputs, one of which is true , The output is true ( It's similar to having a car and a house. If one of them is true, he can get married , But other situations also need to be considered )
  

• Not :
  

And cause and effect diagram Steps for designing test cases :

1. Analyze all inputs and outputs ;
2. Find the relationship between input and output ;
3. Draw a cause and effect diagram according to the relationship picture ;
4. Draw a decision diagram according to the causal picture ;
5. Write test cases according to the decision diagram ~

2.6. Orthogonal method

Design test cases according to the orthogonal method , It's from A lot of experimental data ( Test data ) To get the best combination of data according to the orthogonal principle , According to the results of the optimal data combination test , To analyze the results of the whole test , This is not used much , Therefore, there is no more introduction !

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That's all about test cases , Test cases are very important for testers , Therefore, we must practice more , Use these methods to construct test cases !!!