doc: fix default maxBuffer size

Correctly document the default maxBuffer size for execSync,
execFileSync, and spawnSync. It is 200 * 1024, not Infinity.
Add tests to verify behaviour is as documented.

PR-URL: https://github.com/nodejs/node/pull/22894
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/test/parallel/test-child-process-execfile-maxbuf.js b/test/parallel/test-child-process-execfile-maxbuf.js
new file mode 100644
index 0000000000..ba074630a1
--- /dev/null
+++ b/test/parallel/test-child-process-execfile-maxbuf.js
@@ -0,0 +1,94 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { execFile } = require('child_process');
+
+function checkFactory(streamName) {
+  return common.mustCall((err) => {
+    assert(err instanceof RangeError);
+    assert.strictEqual(err.message, `${streamName} maxBuffer length exceeded`);
+    assert.strictEqual(err.code, 'ERR_CHILD_PROCESS_STDIO_MAXBUFFER');
+  });
+}
+
+// default value
+{
+  execFile(
+    process.execPath,
+    ['-e', 'console.log("a".repeat(200 * 1024))'],
+    checkFactory('stdout')
+  );
+}
+
+// default value
+{
+  execFile(
+    process.execPath,
+    ['-e', 'console.log("a".repeat(200 * 1024 - 1))'],
+    common.mustCall((err, stdout, stderr) => {
+      assert.ifError(err);
+      assert.strictEqual(stdout.trim(), 'a'.repeat(200 * 1024 - 1));
+      assert.strictEqual(stderr, '');
+    })
+  );
+}
+
+{
+  const options = { maxBuffer: Infinity };
+
+  execFile(
+    process.execPath,
+    ['-e', 'console.log("hello world");'],
+    options,
+    common.mustCall((err, stdout, stderr) => {
+      assert.ifError(err);
+      assert.strictEqual(stdout.trim(), 'hello world');
+      assert.strictEqual(stderr, '');
+    })
+  );
+}
+
+{
+  execFile('echo', ['hello world'], { maxBuffer: 5 }, checkFactory('stdout'));
+}
+
+const unicode = '中文测试'; // length = 4, byte length = 12
+
+{
+  execFile(
+    process.execPath,
+    ['-e', `console.log('${unicode}');`],
+    { maxBuffer: 10 },
+    checkFactory('stdout'));
+}
+
+{
+  execFile(
+    process.execPath,
+    ['-e', `console.error('${unicode}');`],
+    { maxBuffer: 10 },
+    checkFactory('stderr')
+  );
+}
+
+{
+  const child = execFile(
+    process.execPath,
+    ['-e', `console.log('${unicode}');`],
+    { encoding: null, maxBuffer: 10 },
+    checkFactory('stdout')
+  );
+
+  child.stdout.setEncoding('utf-8');
+}
+
+{
+  const child = execFile(
+    process.execPath,
+    ['-e', `console.error('${unicode}');`],
+    { encoding: null, maxBuffer: 10 },
+    checkFactory('stderr')
+  );
+
+  child.stderr.setEncoding('utf-8');
+}