lib: fix event race condition with -e

Commit c5b07d4 ("lib: fix beforeExit not working with -e") runs the
to-be-evaluated code at a later time than before because it switches
from `process.nextTick()` to `setImmediate()`.

It affects `-e 'process.on("message", ...)'` because there is now a
larger time gap between startup and attaching the event listener,
increasing the chances of missing early messages.  I'm reasonably
sure `process.nextTick()` was also susceptible to that, only less
pronounced.

Avoid the problem altogether by evaluating the code synchronously.
Harmonizes the logic with `Module.runMain()` from lib/module.js
which also calls `process._tickCallback()` afterwards.

PR-URL: https://github.com/nodejs/node/pull/11958
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/test/parallel/test-cli-eval.js b/test/parallel/test-cli-eval.js
index 6d21b5d50b..34681bd235 100644
--- a/test/parallel/test-cli-eval.js
+++ b/test/parallel/test-cli-eval.js
@@ -171,6 +171,25 @@ child.exec(`${nodejs} --use-strict -p process.execArgv`,
   assert.strictEqual(proc.stdout, 'start\nbeforeExit\nexit\n');
 }
 
+// Regression test for https://github.com/nodejs/node/issues/11948.
+{
+  const script = `
+      process.on('message', (message) => {
+        if (message === 'ping') process.send('pong');
+        if (message === 'exit') process.disconnect();
+      });
+  `;
+  const proc = child.fork('-e', [script]);
+  proc.on('exit', common.mustCall((exitCode, signalCode) => {
+    assert.strictEqual(exitCode, 0);
+    assert.strictEqual(signalCode, null);
+  }));
+  proc.on('message', (message) => {
+    if (message === 'pong') proc.send('exit');
+  });
+  proc.send('ping');
+}
+
 [ '-arg1',
   '-arg1 arg2 --arg3',
   '--',