test: allow tests to pass without internet

PR-URL: https://github.com/nodejs/node/pull/21909
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Lance Ball <lball@redhat.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/test/internet/test-dns-promises-resolve.js b/test/internet/test-dns-promises-resolve.js
new file mode 100644
index 0000000000..430f425137
--- /dev/null
+++ b/test/internet/test-dns-promises-resolve.js
@@ -0,0 +1,42 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+
+const dnsPromises = require('dns').promises;
+
+// Error when rrtype is invalid.
+{
+  const rrtype = 'DUMMY';
+  common.expectsError(
+    () => dnsPromises.resolve('example.org', rrtype),
+    {
+      code: 'ERR_INVALID_OPT_VALUE',
+      type: TypeError,
+      message: `The value "${rrtype}" is invalid for option "rrtype"`
+    }
+  );
+}
+
+// Error when rrtype is a number.
+{
+  const rrtype = 0;
+  common.expectsError(
+    () => dnsPromises.resolve('example.org', rrtype),
+    {
+      code: 'ERR_INVALID_ARG_TYPE',
+      type: TypeError,
+      message: 'The "rrtype" argument must be of type string. ' +
+               `Received type ${typeof rrtype}`
+    }
+  );
+}
+
+// rrtype is undefined, it's same as resolve4
+{
+  (async function() {
+    const rrtype = undefined;
+    const result = await dnsPromises.resolve('example.org', rrtype);
+    assert.ok(result !== undefined);
+    assert.ok(result.length > 0);
+  })();
+}