test,net: add tests for server.connections

There were no tests confirming situations where server.connections
should return `null`. Add a test for that situation.

Expand existing server.connection test slightly to check value.

Refactor (mostly spacing) code for server.connections setter.

PR-URL: https://github.com/nodejs/node/pull/10762
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/test/parallel/test-net-server-connections-child-null.js b/test/parallel/test-net-server-connections-child-null.js
new file mode 100644
index 0000000000..a8a1346fec
--- /dev/null
+++ b/test/parallel/test-net-server-connections-child-null.js
@@ -0,0 +1,44 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const fork = require('child_process').fork;
+const net = require('net');
+
+if (process.argv[2] === 'child') {
+
+  process.on('message', (msg, socket) => {
+    socket.end('goodbye');
+  });
+
+  process.send('hello');
+
+} else {
+
+  const child = fork(process.argv[1], ['child']);
+
+  const runTest = common.mustCall(() => {
+
+    const server = net.createServer();
+
+    // server.connections should start as 0
+    assert.strictEqual(server.connections, 0);
+    server.on('connection', (socket) => {
+      child.send({what: 'socket'}, socket);
+    });
+    server.on('close', () => {
+      child.kill();
+    });
+
+    server.listen(0, common.mustCall(() => {
+      const connect = net.connect(server.address().port);
+
+      connect.on('close', common.mustCall(() => {
+        // now server.connections should be null
+        assert.strictEqual(server.connections, null);
+        server.close();
+      }));
+    }));
+  });
+
+  child.on('message', runTest);
+}