test: Add comprehensive tests for mongoFieldToParseSchemaField type validation and clear error message

- Add tests for valid field type conversions
- Add tests for invalid type handling (null, undefined, non-string values)
- Ensure Parse.Error code is thrown for invalid inputs
- Test coverage for the type validation improvements
- Add a clear error explanation

Author: rgunindi

spec/MongoSchemaCollectionAdapter.spec.js

@@ -96,4 +96,107 @@ describe('MongoSchemaCollection', () => {
     });
     done();
   });
+
+  describe('mongoFieldToParseSchemaField function', () => {
+    // Test successful type conversions
+    it('should convert valid mongo field types to parse schema fields', () => {
+      const testCases = [
+        { input: 'string', expected: { type: 'String' } },
+        { input: 'number', expected: { type: 'Number' } },
+        { input: 'boolean', expected: { type: 'Boolean' } },
+        { input: 'date', expected: { type: 'Date' } },
+        { input: 'map', expected: { type: 'Object' } },
+        { input: 'object', expected: { type: 'Object' } },
+        { input: 'array', expected: { type: 'Array' } },
+        { input: 'geopoint', expected: { type: 'GeoPoint' } },
+        { input: 'file', expected: { type: 'File' } },
+        { input: 'bytes', expected: { type: 'Bytes' } },
+        { input: 'polygon', expected: { type: 'Polygon' } },
+        { input: '*_User', expected: { type: 'Pointer', targetClass: '_User' } },
+        { input: '*Post', expected: { type: 'Pointer', targetClass: 'Post' } },
+        { input: 'relation<_User>', expected: { type: 'Relation', targetClass: '_User' } },
+        { input: 'relation<Post>', expected: { type: 'Relation', targetClass: 'Post' } },
+      ];
+
+      testCases.forEach(({ input, expected }) => {
+        const result = MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+          _id: 'TestClass',
+          testField: input,
+        });
+
+        expect(result.fields.testField).toEqual(expected);
+      });
+    });
+
+    // Test error handling for invalid types (non-string values)
+    it('should throw error for invalid field types', () => {
+      const invalidInputs = [
+        null,
+        undefined,
+        123,
+        true,
+        false,
+        {},
+        [],
+        '',
+      ];
+
+      invalidInputs.forEach(invalidInput => {
+        expect(() => {
+          MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+            _id: 'TestClass',
+            testField: invalidInput,
+          });
+        }).toThrow();
+      });
+    });
+
+    it('should throw error with correct message for null input', () => {
+      try {
+        MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+          _id: 'TestClass',
+          testField: null,
+        });
+      } catch (error) {
+        expect(error.code).toBe(255);
+        expect(error.message).toContain('Invalid field type');
+      }
+    });
+
+    it('should throw error with correct message for undefined input', () => {
+      try {
+        MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+          _id: 'TestClass',
+          testField: undefined,
+        });
+      } catch (error) {
+        expect(error.code).toBe(255);
+        expect(error.message).toContain('Invalid field type');
+      }
+    });
+
+    it('should throw error with correct message for non-string input', () => {
+      try {
+        MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+          _id: 'TestClass',
+          testField: 123,
+        });
+      } catch (error) {
+        expect(error.code).toBe(255);
+        expect(error.message).toContain('Invalid field type');
+      }
+    });
+
+    it('should throw error with correct message for empty string input', () => {
+      try {
+        MongoSchemaCollection._TESTmongoSchemaToParseSchema({
+          _id: 'TestClass',
+          testField: '',
+        });
+      } catch (error) {
+        expect(error.code).toBe(255);
+        expect(error.message).toContain('Invalid field type');
+      }
+    });
+  });
 });

src/Adapters/Storage/Mongo/MongoSchemaCollection.js

@@ -6,7 +6,7 @@ function mongoFieldToParseSchemaField(type) {
   if (!type || typeof type !== 'string') {
     throw new Parse.Error(
       Parse.Error.INVALID_SCHEMA_OPERATION,
-      `Invalid field type: ${type}. Expected a string. Field type must be one of: string, number, boolean, date, map, object, array, geopoint, file, bytes, polygon, or a valid relation/pointer format.`
+      `Invalid field type: ${type}. Expected a string. Fix the type mismatch in your schema configuration.`
     );
   }