From 17d88a740bf3478219c25e1f7c6d712a59bdcafa Mon Sep 17 00:00:00 2001
From: Robin Bolscher <robinbolscher@gmail.com>
Date: Mon, 6 Oct 2025 15:51:21 +0200
Subject: [PATCH] test(DataType): Add tests for handling undefined and null
 fields in copy

Added tests to demonstrate issues with copying maps that contain
undefined or null fields. These tests are currently skipped as they
fail.
---
 test/DataTypes.test.js | 62 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/test/DataTypes.test.js b/test/DataTypes.test.js
index 23371a4..15b71a3 100644
--- a/test/DataTypes.test.js
+++ b/test/DataTypes.test.js
@@ -26,5 +26,67 @@ describe('DataType', function() {
       testMap.constructor.toBuffer(buffer, bufferOffset, testMap.length, bits, testMap);
       assert.deepEqual(buffer, expectedBuffer, 'Static toBuffer failed');
     });
+
+    // This test demonstrates an issue with copying maps with undefined/null fields
+    // The copy operation throws an error when copying if there are undefined fields
+    // This test is skipped as it currently fails, but shows the issue
+    // eslint-disable-next-line mocha/no-skipped-tests
+    it.skip('copy undefined field type error issue', async function() {
+      const Map8 = DataTypes.map8('first', 'second', 'third', undefined, 'fourth');
+      const brokenMap = Map8.fromBuffer(Buffer.from([0b11111]));
+
+      // This throws because `setBits` tries to map `null` or `undefined` to a field name which
+      // does not exist therefore it has no way of knowing what index to set and throws an error
+      // as expected.
+      brokenMap.copy();
+
+      /*
+     TypeError: undefined is an invalid field
+      at /Users/robinbolscher/development/node-data-types/lib/DataTypes.js:77:44
+      at Array.map (<anonymous>)
+      at Bitmap.setBits (lib/DataTypes.js:76:10)
+      at new Bitmap (lib/DataTypes.js:39:23)
+      at Bitmap.copy (lib/DataTypes.js:129:12)
+      at Context.<anonymous> (test/DataTypes.test.js:41:17)
+      at process.processImmediate (node:internal/timers:476:21)
+      */
+    });
+
+    // This test demonstrates an issue with copying maps with null/undefined fields
+    // The copied map can lose null fields in the toArray representation
+    // This test is skipped as it currently fails, but shows the issue
+    // eslint-disable-next-line mocha/no-skipped-tests
+    it.skip('copy inequality issue', async function() {
+      const Map8 = DataTypes.map8('first', 'second', 'third', null, 'fourth', undefined, 'fifth');
+      const brokenMap = Map8.fromBuffer(Buffer.from([0b1111111]));
+      const brokenMapArray = brokenMap.toArray();
+      const copiedBrokenMap = brokenMap.copy();
+      const copiedBrokenMapArray = copiedBrokenMap.toArray();
+
+      assert.deepEqual(brokenMapArray, copiedBrokenMapArray);
+      /*
+        AssertionError [ERR_ASSERTION]: Expected values to be loosely deep-equal:
+        [
+          'first',
+          'second',
+          'third',
+          null,
+          'fourth',
+          null,
+          'fifth'
+        ]
+
+        should loosely deep-equal
+
+        [
+          'first',
+          'second',
+          'third',
+          null,
+          'fourth',
+          'fifth'
+        ]
+      */
+    });
   });
 });