Software testing and quality learning notes 3 -- white box testing

1. Two kinds of white box test Common technology :
Coverage test : During the test , Tests that aim to cover certain program elements .
Path test : Speaking from the flow chart , One execution of the program corresponds to a path from entry to exit , Path tests are path tests . In a broad sense , Any test related to path analysis can be called path test .
2. White box testing -- The basic path method
On the premise that all paths cannot be covered , If every independent path of a program has been tested , Then it can be considered that every statement in the program has been verified , That is, the statement coverage . This test method is commonly known as Basic path test method .
3. The control flow chart
It can be abbreviated as flow graph , It is obtained by simplifying the program flow chart , It can more prominently represent the structure of program control flow .
The control flow diagram includes two graphical symbols : Nodes and control flow lines .
node Represented by a marked circle , It can represent one or more statements 、 A sequence of processing boxes and A condition decision box .
Control flow line Represented by an arc or line with an arrow , Can be called edge . It represents the control flow in the program .
Be careful ： Every circle Representing control flow graph node , It can represent one or more statements . The number in the circle corresponds to the number of a line in the program （ That is, you can write multiple numbers ）. The arrow represents the direction of the edge , That is, control the flow direction
See the picture for details

  among , Nodes that contain conditions are called decision nodes （ Also called predicate node ), The edge from the decision node must end at a node , The range bounded by edges and nodes is called a region .
4. Graph matrix
The graph matrix is Matrix of control flow graph Representation form .
The graph matrix is a square matrix , Its dimension is equal to the number of nodes of the control flow graph . Each column and row in the matrix corresponds to the identified node , Matrix elements correspond to edges between nodes .
Usually , In the control flow diagram Nodes are identified by numbers , The side is marked with letters . If in the control flow diagram, from i Node to j Nodes have an ID of x The edges of are connected , Then in the corresponding graph matrix The first i Xing di j Column There is a non empty element x.
5. Ring complexity and its calculation method
Ring complexity is also called cycle complexity , Based on graph theory , It provides us with very useful software metrics . The ring complexity can be calculated by one of the following two methods :
Method 1： Given control flow diagram G Ring complexity 1 v(G), Defined as
v(G)=E-N+2       Ring complexity = The number of sides - Number of nodes +2
among ,E Is the number of edges in the control flow graph ,N Is the number of nodes in the control flow graph .
Method 2： Given control flow diagram G Ring complexity 1 v(G), It can also be defined as
v(G)= P+1         Ring complexity = Determine the number of nodes +1
among ,P Is the control flow diagram G Determine the number of nodes in .
6. Independent path
It refers to the program path in which at least a new set of processing statements or a new condition is introduced into the program .
Adopt the terminology of flow graph , That is, the independent path must Include at least one edge that has not been used before defining the path this time .
Be careful :“..." Indicates that the remaining paths are optional , The reason is that there is a circular structure .
7. Basic path test method test steps
· Basic path test steps :
1. Draw the control flow diagram of the program
2. Computational flow graph G The complexity of the loop V(G)
3. Determine the basic path set that contains only independent paths
4. According to the independent path above , Design test cases , Make the program follow the above
Independent path execution .