More protobufjs migration

ts/test-both/util/dropNull_test.ts

@@ -2,7 +2,12 @@
 // SPDX-License-Identifier: AGPL-3.0-only
 import { assert } from 'chai';
 
-import { dropNull } from '../../util/dropNull';
+import { dropNull, shallowDropNull } from '../../util/dropNull';
+
+type Test = {
+  a: number | null;
+  b: number | undefined;
+};
 
 describe('dropNull', () => {
   it('swaps null with undefined', () => {
@@ -16,4 +21,42 @@ describe('dropNull', () => {
   it('non-null values undefined be', () => {
     assert.strictEqual(dropNull('test'), 'test');
   });
+
+  describe('shallowDropNull', () => {
+    it('return undefined with given null', () => {
+      assert.strictEqual(shallowDropNull<Test>(null), undefined);
+    });
+
+    it('return undefined with given undefined', () => {
+      assert.strictEqual(shallowDropNull<Test>(undefined), undefined);
+    });
+
+    it('swaps null with undefined', () => {
+      const result:
+        | {
+            a: number | undefined;
+            b: number | undefined;
+          }
+        | undefined = shallowDropNull<Test>({
+        a: null,
+        b: 1,
+      });
+
+      assert.deepStrictEqual(result, { a: undefined, b: 1 });
+    });
+
+    it('leaves undefined be', () => {
+      const result:
+        | {
+            a: number | undefined;
+            b: number | undefined;
+          }
+        | undefined = shallowDropNull<Test>({
+        a: 1,
+        b: undefined,
+      });
+
+      assert.deepStrictEqual(result, { a: 1, b: undefined });
+    });
+  });
 });