fix(NODE-3681): Typescript error in Collection.findOneAndModify UpdateFilter $currentDate

src/mongo_types.ts

@@ -219,7 +219,7 @@ export type NotAcceptedFields<TSchema, FieldType> = {
 /** @public */
 export type OnlyFieldsOfType<TSchema, FieldType = any, AssignableType = FieldType> = IsAny<
   TSchema[keyof TSchema],
-  Record<string, FieldType>,
+  AssignableType extends FieldType ? Record<string, FieldType> : Record<string, AssignableType>,
   AcceptedFields<TSchema, FieldType, AssignableType> &
     NotAcceptedFields<TSchema, FieldType> &
     Record<string, AssignableType>

test/types/community/collection/updateX.test-d.ts

@@ -60,6 +60,13 @@ expectAssignable<UpdateFilter<Document>>({ $inc: { anyKeyWhatsoever: 2 } });
 // But this no longer asserts anything about what the original keys map to
 expectNotType<UpdateFilter<Document>>({ $inc: { numberField: '2' } });
 
+expectAssignable<UpdateFilter<Document>>({
+  $currentDate: { anyKeyWhatsoever: { $type: 'timestamp' } }
+});
+expectAssignable<UpdateFilter<Document>>({ $currentDate: { anyKeyWhatsoever: { $type: 'date' } } });
+expectAssignable<UpdateFilter<Document>>({ $currentDate: { anyKeyWhatsoever: true } });
+expectNotType<UpdateFilter<Document>>({ $currentDate: { anyKeyWhatsoever: 'true' } });
+expectNotType<UpdateFilter<Document>>({ $currentDate: { anyKeyWhatsoever: { key2: true } } });
 // collection.updateX tests
 const client = new MongoClient('');
 const db = client.db('test');

test/types/helper_types.test-d.ts

@@ -69,6 +69,9 @@ expectAssignable<OnlyFieldsOfType<{ a: number; b: string }, number>>({ a: 2 });
 expectAssignable<OnlyFieldsOfType<{ a: number; b: string }, string>>({ b: 'hello' });
 expectAssignable<OnlyFieldsOfType<{ a: number; b: string }, string, boolean>>({ b: true });
 
+// test the case in which AssignableType does not inherit from FieldType, and AssignableType is provided
+expectAssignable<OnlyFieldsOfType<any, string, boolean>>({ b: false });
+
 // test generic schema, essentially we expect nearly no safety here
 expectAssignable<OnlyFieldsOfType<Document, NumericType | undefined>>({ someKey: 2 });
 // We can still at least enforce the type that the keys map to