快考试了，发现几个名词还是很有意思的。
DD Path：全称是Decision-to-decision_path，在wikipedia上说得很明白，决策路径，可能有人听过决策树，决策树是一种深层次的表现形式，而决策路径表示（引用wikipedia上的原文如下）：
DD Path：全称是Decision-to-decision_path，在wikipedia上说得很明白，决策路径，可能有人听过决策树，决策树是一种深层次的表现形式，而决策路径表示（引用wikipedia上的原文如下）：
A decision-to-decision path, or DD-Path, is a path of execution (usually through a graph representing a program, such as a flow-chart) that does not include any conditional nodes. That is, it is the path of execution between two decisions.
DD (decision-decision)' path is a path of nodes in a directed graph. A chain is a path in which:
- Initial and terminal nodes are distinct
- All interior nodes have in-degree = 1 and out-degree = 1
A DD-path is a chain in a program graph such that:
- It consists of a single node with in-degree = 0 (initial node)
- It consists of a single node with out-degree = 0 (terminal node)
- It consists of a single node with in-deg ≥ 2 or out-deg ≥ 2
- It consists of a single node with in-deg = 1 and out-deg = 1
It is a maximal chain of length ≥ 1.
MM-Path：在google搜索了半天，也找不到其含义，翻阅历来试卷，全称是Message-Module-Path，查阅论文资料找到一篇文章《一个基于UML协作图的集成测试用例生成方法》，上面提到“方法／消息路径(MM-path)”，应该表述有误。在测试里面，MM-路径是功能性测试和结构性测试的一种混合。
