child_process: spawn ignores options in case args is undefined

spawn method ignores 3-d argument 'options' in case
the second one 'args' equals to 'undefined'.

Fixes: https://github.com/nodejs/node/issues/24912

PR-URL: https://github.com/nodejs/node/pull/24913
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/test/parallel/test-child-process-spawn-args.js b/test/parallel/test-child-process-spawn-args.js
new file mode 100644
index 0000000000..35a1ea4020
--- /dev/null
+++ b/test/parallel/test-child-process-spawn-args.js
@@ -0,0 +1,53 @@
+'use strict';
+
+// This test confirms that `undefined`, `null`, and `[]`
+// can be used as a placeholder for the second argument (`args`) of `spawn()`.
+// Previously, there was a bug where using `undefined` for the second argument
+// caused the third argument (`options`) to be ignored.
+// See https://github.com/nodejs/node/issues/24912.
+
+const assert = require('assert');
+const { spawn } = require('child_process');
+
+const common = require('../common');
+const tmpdir = require('../common/tmpdir');
+
+const command = common.isWindows ? 'cd' : 'pwd';
+const options = { cwd: tmpdir.path };
+
+if (common.isWindows) {
+  // This test is not the case for Windows based systems
+  // unless the `shell` options equals to `true`
+
+  options.shell = true;
+}
+
+const testCases = [
+  undefined,
+  null,
+  [],
+];
+
+const expectedResult = tmpdir.path.trim().toLowerCase();
+
+(async () => {
+  const results = await Promise.all(
+    testCases.map((testCase) => {
+      return new Promise((resolve) => {
+        const subprocess = spawn(command, testCase, options);
+
+        let accumulatedData = Buffer.alloc(0);
+
+        subprocess.stdout.on('data', common.mustCall((data) => {
+          accumulatedData = Buffer.concat([accumulatedData, data]);
+        }));
+
+        subprocess.stdout.on('end', () => {
+          resolve(accumulatedData.toString().trim().toLowerCase());
+        });
+      });
+    })
+  );
+
+  assert.deepStrictEqual([...new Set(results)], [expectedResult]);
+})();