v8.takeCoverage()

v8.takeCoverage()方法允许用户按需将 NODE_V8_COVERAGE 开始的覆盖写入磁盘。 此方法可以在进程的生命周期内多次调用。 每次执行计数器将被重置，并且新的覆盖报告将写入 NODE_V8_COVERAGE 指定的目录。

当进程即将退出时，除非在进程退出前调用 v8.stopCoverage()，否则最后一个覆盖仍会写入磁盘。

The v8.takeCoverage() method allows the user to write the coverage started by NODE_V8_COVERAGE to disk on demand. This method can be invoked multiple times during the lifetime of the process. Each time the execution counter will be reset and a new coverage report will be written to the directory specified by NODE_V8_COVERAGE.

When the process is about to exit, one last coverage will still be written to disk unless v8.stopCoverage() is invoked before the process exits.