test(DataType): Add tests for handling undefined and null fields in copy

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'
+        ]
+      */
+    });
   });
 });