fix: empty newline printed to stderr

Starting in v7.7.0 running `npm` (no args) is printing an empty newline
to stderr.

This fixes that by correctly exiting via errorHandler and avoiding
hitting the cb() never called error and adds a test to make sure we
avoid that regression moving forward.

Fixes: https://github.com/nodejs/node/pull/37678#issuecomment-808734374

Co-authored-by: Gar <gar+gh@danger.computer>

1 files changed, 25 insertions, 4 deletions

diff --git a/test/lib/cli.js b/test/lib/cli.js
index 40da77bf4..28e44394e 100644
--- a/test/lib/cli.js
+++ b/test/lib/cli.js
@@ -172,17 +172,37 @@ t.test('gracefully handles error printing usage', t => {
   t.teardown(() => {
     npmock.output = output
     errorHandlerCb = null
+    errorHandlerCalled = null
   })
   const proc = {
-    argv: ['node', 'npm', 'asdf'],
+    argv: ['node', 'npm'],
     on: () => {},
   }
   npmock.argv = []
-  npmock.output = (msg) => {
-    throw new Error('test exception')
+  errorHandlerCb = () => {
+    t.match(errorHandlerCalled, [], 'should call errorHandler with no args')
+    t.end()
+  }
+  cli(proc)
+})
+
+t.test('handles output error', t => {
+  const { output } = npmock
+  t.teardown(() => {
+    npmock.output = output
+    errorHandlerCb = null
+    errorHandlerCalled = null
+  })
+  const proc = {
+    argv: ['node', 'npm'],
+    on: () => {},
+  }
+  npmock.argv = []
+  npmock.output = () => {
+    throw new Error('ERR')
   }
   errorHandlerCb = () => {
-    t.match(errorHandlerCalled, /test exception/)
+    t.match(errorHandlerCalled, /ERR/, 'should call errorHandler with error')
     t.end()
   }
   cli(proc)
@@ -191,6 +211,7 @@ t.test('gracefully handles error printing usage', t => {
 t.test('load error calls error handler', t => {
   t.teardown(() => {
     errorHandlerCb = null
+    errorHandlerCalled = null
     LOAD_ERROR = null
   })