收集代码覆盖率

¥Collecting code coverage

当 Node.js 以 --experimental-test-coverage 命令行标志启动时，代码覆盖率将被收集并在所有测试完成后报告统计信息。如果使用 NODE_V8_COVERAGE 环境变量指定代码覆盖目录，则生成的 V8 覆盖文件写入该目录。默认情况下，node_modules/ 目录中的 Node.js 核心模块和文件不包含在覆盖率报告中。但是，它们可以通过 --test-coverage-include 标志明确包含。如果启用覆盖，覆盖报告将通过 'test:coverage' 事件发送到任何 测试报告器。

¥When Node.js is started with the --experimental-test-coverage command-line flag, code coverage is collected and statistics are reported once all tests have completed. If the NODE_V8_COVERAGE environment variable is used to specify a code coverage directory, the generated V8 coverage files are written to that directory. Node.js core modules and files within node_modules/ directories are, by default, not included in the coverage report. However, they can be explicity included via the --test-coverage-include flag. If coverage is enabled, the coverage report is sent to any test reporters via the 'test:coverage' event.

可以使用以下注释语法在一系列行上禁用覆盖：

¥Coverage can be disabled on a series of lines using the following comment syntax:

/* node:coverage disable */
if (anAlwaysFalseCondition) {
  // Code in this branch will never be executed, but the lines are ignored for
  // coverage purposes. All lines following the 'disable' comment are ignored
  // until a corresponding 'enable' comment is encountered.
  console.log('this is never executed');
}
/* node:coverage enable */ 拷贝

也可以针对指定行数禁用覆盖。在指定的行数之后，将自动重新启用覆盖。如果未明确提供行数，则忽略单行。

¥Coverage can also be disabled for a specified number of lines. After the specified number of lines, coverage will be automatically reenabled. If the number of lines is not explicitly provided, a single line is ignored.

/* node:coverage ignore next */
if (anAlwaysFalseCondition) { console.log('this is never executed'); }

/* node:coverage ignore next 3 */
if (anAlwaysFalseCondition) {
  console.log('this is never executed');
} 拷贝