fix(query-parser): provide stringify handler for BSONRegExp COMPASS-7008 (#353)

Author: Anemy

packages/query-parser/src/index.spec.ts

@@ -521,6 +521,75 @@ e  s`,
         const stringified = stringify(res);
         assert.equal(stringified, '{name: RegExp("\'")}');
       });
+
+      it('handles $regex object format (keeps format)', function () {
+        const res = parseFilter(
+          '{"name": {"$regex": "pineapple", "$options": "i"}}'
+        );
+        const stringified = stringify(res);
+        assert.equal(
+          stringified,
+          "{name: {$regex: 'pineapple',$options: 'i'}}"
+        );
+      });
+
+      it('handles /regex/ format', function () {
+        const res = {
+          name: /pineapple/,
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: RegExp("pineapple")}');
+      });
+    });
+
+    context('when provided a BSONRegExp', function () {
+      it('stringifies correctly with options', function () {
+        const res = {
+          name: new bson.BSONRegExp('pineapple', 'i'),
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: RegExp("pineapple", \'i\')}');
+      });
+
+      it('stringifies correctly with quotes', function () {
+        const res = {
+          name: new bson.BSONRegExp('"\'', 'i'),
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: RegExp("\\"\'", \'i\')}');
+      });
+
+      it('stringifies correctly without options', function () {
+        const res = {
+          name: new bson.BSONRegExp('pineapple'),
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: RegExp("pineapple")}');
+      });
+
+      it('stringifies into BSONRegExp when js RegExp cannot handle an option', function () {
+        const res = {
+          name: new bson.BSONRegExp(
+            'pineapple',
+            'x' /* x flag is not valid in js but valid in BSONRegExp*/
+          ),
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: BSONRegExp("pineapple", \'x\')}');
+      });
+
+      it('stringifies into BSONRegExp when js RegExp cannot handle the regex', function () {
+        const res = {
+          name: new bson.BSONRegExp(
+            // Perl Compatible Regular Expressions supported feature that isn't in regular
+            // js RegExp: case-insensitive match.
+            '(?i)a(?-i)cme',
+            'i'
+          ),
+        };
+        const stringified = stringify(res);
+        assert.equal(stringified, '{name: BSONRegExp("(?i)a(?-i)cme", \'i\')}');
+      });
     });
 
     context('when provided a Binary', function () {

packages/query-parser/src/stringify.ts

@@ -3,6 +3,7 @@
  */
 import type {
   Binary,
+  BSONRegExp,
   BSONValue,
   Code,
   DBRef,
@@ -134,6 +135,18 @@ const BSON_TO_JS_STRING = {
 
     return `RegExp(${JSON.stringify(v.source)}${hasOptions ? `, '${o}'` : ''})`;
   },
+  BSONRegExp: function (v: BSONRegExp) {
+    const hasOptions = v.options && v.options?.length > 0;
+    let ctor = 'RegExp';
+    try {
+      RegExp(v.pattern, v.options || undefined);
+    } catch {
+      ctor = 'BSONRegExp';
+    }
+    return `${ctor}(${JSON.stringify(v.pattern)}${
+      hasOptions ? `, '${v.options}'` : ''
+    })`;
+  },
 };
 
 /** @public */