fix(shell-api): add toBSON overrides to MinKey/MaxKey ctors MONGOSH-1024 (#1154)

Add `.toBSON` overrides so that sending `MinKey` or `MaxKey`
over the wire results in the same document that `MinKey()` or
`MaxKey()` would have generated, for compatibility with the
legacy shell.

Author: addaleax

packages/cli-repl/test/e2e-bson.spec.ts

@@ -317,6 +317,19 @@ describe('BSON e2e', function() {
       shell.assertNoErrors();
     });
   });
+  describe('MaxKey/MinKey special handling', () => {
+    it('inserts and retrieves MaxKey/MinKey regardless of whether they have been called as functions', async() => {
+      await shell.executeLine(`use ${dbName}`);
+      await shell.executeLine(`db.test.insertOne({
+        maxfn: MaxKey, maxval: MaxKey(), minfn: MinKey, minval: MinKey()
+      })`);
+      const output = await shell.executeLine('db.test.findOne()');
+      expect(output).to.include('maxfn: MaxKey()');
+      expect(output).to.include('maxval: MaxKey()');
+      expect(output).to.include('minfn: MinKey()');
+      expect(output).to.include('minval: MinKey()');
+    });
+  });
   describe('help methods', () => {
     it('ObjectId has help when returned from the server', async() => {
       const value = new bson.ObjectId();

packages/shell-api/src/shell-bson.spec.ts

@@ -1,6 +1,7 @@
 /* eslint camelcase: 0, new-cap: 0 */
 import { CommonErrors, MongoshInvalidInputError } from '@mongosh/errors';
 import { bson } from '@mongosh/service-provider-core';
+import { serialize as bsonSerialize, deserialize as bsonDeserialize } from 'bson';
 import { expect } from 'chai';
 import sinon from 'ts-sinon';
 import { ALL_SERVER_VERSIONS } from './enums';
@@ -77,6 +78,10 @@ describe('Shell BSON', () => {
       const s = new (shellBson.MaxKey as any)();
       expect(s._bsontype).to.equal('MaxKey');
     });
+    it('using toBSON', () => {
+      const s = (shellBson.MaxKey as any).toBSON();
+      expect(s._bsontype).to.equal('MaxKey');
+    });
     it('has help and other metadata', async() => {
       const s = shellBson.MaxKey();
       expect((await toShellResult(s.help)).type).to.equal('Help');
@@ -93,13 +98,31 @@ describe('Shell BSON', () => {
       const s = new (shellBson.MinKey as any)();
       expect(s._bsontype).to.equal('MinKey');
     });
+    it('using toBSON', () => {
+      const s = (shellBson.MinKey as any).toBSON();
+      expect(s._bsontype).to.equal('MinKey');
+    });
     it('has help and other metadata', async() => {
       const s = shellBson.MinKey();
       expect((await toShellResult(s.help)).type).to.equal('Help');
       expect((await toShellResult(s.help())).type).to.equal('Help');
       expect(s.serverVersions).to.deep.equal(ALL_SERVER_VERSIONS);
     });
   });
+  describe('MinKey & MaxKey constructor special handling', () => {
+    it('round-trips through bson as expected', () => {
+      const { MinKey, MaxKey } = shellBson as any;
+      const expected = { a: { $minKey: 1 }, b: { $maxKey: 1 } };
+      function roundtrip(value: any): any {
+        return bson.EJSON.serialize(bsonDeserialize(bsonSerialize(value)));
+      }
+
+      expect(roundtrip({ a: new MinKey(), b: new MaxKey() })).to.deep.equal(expected);
+      expect(roundtrip({ a: MinKey(), b: MaxKey() })).to.deep.equal(expected);
+      expect(roundtrip({ a: MinKey.toBSON(), b: MaxKey.toBSON() })).to.deep.equal(expected);
+      expect(roundtrip({ a: MinKey, b: MaxKey })).to.deep.equal(expected);
+    });
+  });
   describe('ObjectId', () => {
     it('without new', () => {
       const s = shellBson.ObjectId('5ebbe8e2905bb493d6981b6b');
@@ -615,6 +638,7 @@ describe('Shell BSON', () => {
         delete bsonProperties.length;
         delete shellProperties.index; // ObjectId.index is a random number
         delete bsonProperties.index; // ObjectId.index is a random number
+        delete shellProperties.toBSON; // toBSON is something we add for MaxKey/MinKey as a shell-specific extension
         try {
           expect(shellProperties).to.deep.equal(bsonProperties);
         } catch (err) {

packages/shell-api/src/shell-bson.ts

@@ -94,12 +94,13 @@ export default function constructShellBson(bson: typeof BSON, printWarning: (msg
       assertArgsDefinedType([object], ['object'], 'bsonsize');
       return bson.calculateObjectSize(object);
     },
+    // See https://jira.mongodb.org/browse/MONGOSH-1024 for context on the toBSON additions
     MaxKey: Object.assign(function MaxKey(): typeof bson.MaxKey.prototype {
       return new bson.MaxKey();
-    }, { ...bson.MaxKey, prototype: bson.MaxKey.prototype }),
+    }, { ...bson.MaxKey, toBSON: () => new bson.MaxKey(), prototype: bson.MaxKey.prototype }),
     MinKey: Object.assign(function MinKey(): typeof bson.MinKey.prototype {
       return new bson.MinKey();
-    }, { ...bson.MinKey, prototype: bson.MinKey.prototype }),
+    }, { ...bson.MinKey, toBSON: () => new bson.MinKey(), prototype: bson.MinKey.prototype }),
     ObjectId: Object.assign(function ObjectId(id?: string | number | typeof bson.ObjectId.prototype | Buffer): typeof bson.ObjectId.prototype {
       assertArgsDefinedType([id], [[undefined, 'string', 'number', 'object']], 'ObjectId');
       return new bson.ObjectId(id);