test: check that --insecure-http-parser works

Test that using --insecure-http-parser will disable validation of
invalid characters in HTTP headers.

See:
- nodejs#30567

Backport-PR-URL: nodejs#30471
PR-URL: nodejs#31253
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-http-insecure-parser.js

@@ -0,0 +1,35 @@
+// Flags: --insecure-http-parser
+
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+const net = require('net');
+
+const server = http.createServer(function(req, res) {
+  assert.strictEqual(req.headers['content-type'], 'text/te\bt');
+  req.pipe(res);
+});
+
+server.listen(0, common.mustCall(function() {
+  const bufs = [];
+  const client = net.connect(
+    this.address().port,
+    function() {
+      client.write(
+        'GET / HTTP/1.1\r\n' +
+        'Content-Type: text/te\x08t\r\n' +
+        'Connection: close\r\n\r\n');
+    }
+  );
+  client.on('data', function(chunk) {
+    bufs.push(chunk);
+  });
+  client.on('end', common.mustCall(function() {
+    const head = Buffer.concat(bufs)
+      .toString('latin1')
+      .split('\r\n')[0];
+    assert.strictEqual(head, 'HTTP/1.1 200 OK');
+    server.close();
+  }));
+}));