bin-wrap.js

var sw = require('spawn-wrap')
var NYC = require('../index.js')

var config = {}
if (process.env.NYC_CONFIG) config = JSON.parse(process.env.NYC_CONFIG)
config.isChildProcess = true

config._processInfo = {
  pid: process.pid,
  ppid: process.ppid,
  parent: process.env.NYC_PROCESS_ID || null,
  root: process.env.NYC_ROOT_ID
}
if (process.env.NYC_PROCESSINFO_EXTERNAL_ID) {
  config._processInfo.externalId = process.env.NYC_PROCESSINFO_EXTERNAL_ID
  delete process.env.NYC_PROCESSINFO_EXTERNAL_ID
}

if (process.env.NYC_CONFIG_OVERRIDE) {
  var override = JSON.parse(process.env.NYC_CONFIG_OVERRIDE)
  config = Object.assign(config, override)
  process.env.NYC_CONFIG = JSON.stringify(config)
}

;(new NYC(config)).wrap()

sw.runMain()

config-override.diff

diff --git a/bin/wrap.js b/bin/wrap.js
index 1cff275..4e64c2b 100644
--- a/bin/wrap.js
+++ b/bin/wrap.js
@@ -16,6 +16,12 @@ if (process.env.NYC_PROCESSINFO_EXTERNAL_ID) {
   delete process.env.NYC_PROCESSINFO_EXTERNAL_ID
 }
 
+if (process.env.NYC_CONFIG_OVERRIDE) {
+  var override = JSON.parse(process.env.NYC_CONFIG_OVERRIDE)
+  config = Object.assign(config, override)
+  process.env.NYC_CONFIG = JSON.stringify(config)
+}
+
 ;(new NYC(config)).wrap()
 
 sw.runMain()

dump-config.js

const config = JSON.parse(process.env.NYC_CONFIG || /* istanbul ignore next */ '{}')
console.log('in dumper', {include: config.include})

dump-root.js

#!/usr/local/bin/node ./bin/nyc.js --no-exclude-after-remap --include=dump-root.js node

const config = JSON.parse(process.env.NYC_CONFIG || /* istanbul ignore next */ '{}')
const {include,exclude} = config

const dumper = require.resolve('./dump-config.js')
if (process.argv[2] !== 'child') {
  console.error('in parent', {include})
  require('child_process').spawn(process.execPath, [__filename, 'child'], {
    env: {
      ...process.env,
      NYC_CONFIG_OVERRIDE: JSON.stringify({
        include: 'dump-config.js',
      }),
    },
    stdio: 'inherit',
  })
} else {
  // this should run, but not be covered, even though the shebang says to
  // the child run ONLY covers the child file, not the dump-root.js
  console.error('in child', {include})
  require(dumper)
}

output

$ ./dump-root.js
in parent { include: 'dump-root.js' }
in child { include: 'dump-config.js' }
in dumper { include: 'dump-config.js' }
----------------|----------|----------|----------|----------|-------------------|
File            |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------------|----------|----------|----------|----------|-------------------|
All files       |       80 |       75 |      100 |       80 |                   |
 dump-config.js |      100 |      100 |      100 |      100 |                   |
 dump-root.js   |       75 |    66.67 |      100 |       75 |             21,22 |
----------------|----------|----------|----------|----------|-------------------|