[IntelliJ] Create custom code snippet

To standardize code style among different project and teams, snippet is one of the tools to implement coding standard.

However, snippet is the two-side blade for developer. It will introduce duplicate code and result difficult to maintain if abuse. The recommend place to use snippets are:

1. Unit test for high level format;
2. DTO / DAO with specific handling in getter / setter method;
3. Predefined markup (e.g. XML / HTML, JSON, YAML);

In this demo, it will use JUnit parameter test as sample to create snippet.Steps:

1. Create Live Template
   Highlight code would like to add into snippet, press Control + Shift + A, and input save as live template, then click Enter.
2. Add snippet abbreviation and variables.
   In Save as Live Template dialog, in Abbreviation, input name ptest, and variables are format like $variableName$.
   
3. Configure snippet variables.
   Click Edit Variables, in expression, input default value. You can use method provided to customize value (e.g. upper case, camelCase, etc) to fit your need.
   
4. Test snippet.
   In project, type snippet abbreviation, expected it will show in intelli-sense, after press enter, snippet will be render.