用于覆盖MC DC的测试用例的可能组合数

Question

例如表达式Z：=（A而不是B）或（C xor D）; 以下是唯一可能的测试用例组合吗？

   testCaseNO  1 2 3 4 5
      Input A  T T F F F 
      Input B  T F T T T 
      Input C  F F F F T 
      Input D  F F F T F 
     Output Z  F T F T T 

或者以下给出MCDC也可以正常工作？

   testCaseNO  1 2 3 4 5
      Input A  T T T F F 
      Input B  T F T T F 
      Input C  F F T F T 
      Input D  F F T T T 
     Output Z  F T F T F

Answer 1

我不认为第二个适用于MCDC。您没有说明输入A独立地影响输出。在测试用例1中，A是T，输出Z是F.在测试用例4A中，A是F，输入D也变化。所以你不知道哪一个将输出改为T。

Answer 2

Neither of your examples satisfies MC/DC.

To evaluate whether test cases satisfy MC/DC, a good approach is to pair up test cases, so that each pair:

• Differs only in one value
• Gives different results

There should be one such pair for every condition. So, for the first example:

• case 1 and case 3 toggles A, but does not produce a different result
• case 1 and case 2 toggles B, producing a different result
• case 3 and case 5 toggles C, producing a different result
• case 3 and case 4 toggles D, producing a different result

In the second example, the only pair that changes a single input value is cases 1 and 2. All other pairs change two or more values.

A test set that does provide full MC/DC in this case is:

test case No 1 2 3 4 5
Input A      T T F F F
Input B      T F F F F
Input C      F F F T F
Input D      F F F F T
Output Z     F T F T T

• A is satisfied by 2 and 3
• B is satisfied by 1 and 2
• C is satisfied by 3 and 4
• D is satisfied by 3 and 5