test: add lib/utils/error-handler.js tests

Add unit tests to `lib/utils/error-handler.js`, these are very special
since the module handles some internal state through variables which are
not exposed and binds itself to multiple global `process` events.

Also two minor tweaks/fixes to the original implementation:
- Refactored unused param in `reallyExit()`
- Fixed String.prototype.match group capture usage

PR-URL: https://github.com/npm/cli/pull/1742
Credit: @ruyadorno
Close: #1742
Reviewed-by: @isaacs

1 files changed, 4 insertions, 6 deletions

diff --git a/lib/utils/error-handler.js b/lib/utils/error-handler.js
index f713bf021..16abcd67c 100644
--- a/lib/utils/error-handler.js
+++ b/lib/utils/error-handler.js
@@ -90,9 +90,7 @@ const exit = (code, noLog) => {
   log.verbose('exit', code)
   if (log.level === 'silent') noLog = true
 
-  const reallyExit = (er) => {
-    if (er && !code) code = typeof er.errno === 'number' ? er.errno : 1
-
+  const reallyExit = () => {
     itWorked = !code
 
     // Exit directly -- nothing in the CLI should still be running in the
@@ -141,9 +139,9 @@ const errorHandler = (er) => {
     return exit(1, true)
   }
 
-  const m = er.code || er.message.match(/^(?:Error: )?(E[A-Z]+)/)
-  if (m && !er.code) {
-    er.code = m
+  if (!er.code) {
+    const matchErrorCode = er.message.match(/^(?:Error: )?(E[A-Z]+)/)
+    er.code = matchErrorCode && matchErrorCode[1]
   }
 
   for (const k of ['type', 'stack', 'statusCode', 'pkgid']) {