Software testing and quality learning notes 2 - black box testing

1. Black box testing - Cause and effect diagram
We know , When the input conditions of the tested object are interdependent 、 When they restrict each other , fit Decision table method .
When Too many input conditions when , Using the decision table will produce a large number of test cases , And it cannot cover the conditions
The sequential relationship between ----- Cause and effect diagram
2. What is a cause and effect diagram
It's a kind of Using graphic method Analyze various combinations of inputs , So the way to design test cases .
The final result of causality diagram is the judgment table
3. Cause and effect diagram composition
Simple relationship symbols are used in the cause and effect diagram , Connect the left and right nodes in a straight line .
Left node Express Input status （ reason ), Right node Express Output status ( result ).
0 Indicates that a state does not appear ,1 Indicates that a state appears .
4. Relationship symbols of cause and effect diagram
Identity
Indicates the one-to-one correspondence between cause and result . If the cause appears , The result appears ; If the cause does not appear , Then the result does not appear
Not
Indicates a negative relationship between cause and result . If the cause appears , Then the result does not appear ; If the cause does not appear , Instead, the result appears .
or
It means if one of several reasons appears , The result appears ; Only when ‘ When these reasons do not appear , The result doesn't appear .
And
If several reasons occur , The result is ; If one of several reasons doesn't appear , The result doesn't appear .

5. Constraint symbol of cause and effect diagram
In practical problems , There may also be some dependencies between input states , It's called constraint . for example , Some input conditions cannot appear at the same time .
E constraint （ different / Mutually exclusive ）exclusive
It means that several reasons will not be established at the same time ;
Maybe they are not established , But at most one is true .
I constraint ( or / contain )in
At least one of the several reasons must be true , Of course, it may all be true .
O constraint （ only )only
It means that only one of several reasons must be true .
R constraint （ requirement )requst
Said when a When it appears ,b Must also appear .
M constraint （ shielding )mandate
Said when a yes 1 when ,b Must be 0; And when a by 0 when ,b The value of is not necessarily .

6. Cause and effect diagram design use case steps
Find out the input and output and identify -> Analyze the relationship between input and output -> Draw a cause and effect diagram -> The causality diagram is transformed into a decision table -> Generate test cases