test(formUtils): add unit tests for getFormFieldById

src/app/modules/form/__tests__/form.utils.spec.ts

@@ -1,6 +1,11 @@
-import { Permission } from 'src/types'
+import { ObjectId } from 'bson-ext'
+import { Types } from 'mongoose'
 
-import { getCollabEmailsWithPermission } from '../form.utils'
+import { BasicField, IFieldSchema, Permission } from 'src/types'
+
+import { generateDefaultField } from 'tests/unit/backend/helpers/generate-form-data'
+
+import { getCollabEmailsWithPermission, getFormFieldById } from '../form.utils'
 
 const MOCK_EMAIL_1 = '[email protected]'
 const MOCK_EMAIL_2 = '[email protected]'
@@ -42,4 +47,63 @@ describe('form.utils', () => {
       expect(result).toEqual([MOCK_EMAIL_2])
     })
   })
+
+  describe('getFormFieldById', () => {
+    it('should return form field with valid id when form fields given is a primitive array', async () => {
+      // Arrange
+      const fieldToFind = generateDefaultField(BasicField.HomeNo)
+      const formFields = [generateDefaultField(BasicField.Date), fieldToFind]
+
+      // Act
+      const result = getFormFieldById(formFields, fieldToFind._id)
+
+      // Assert
+      expect(result).toEqual(fieldToFind)
+    })
+
+    it('should return form field with valid id when form fields given is a mongoose document array', async () => {
+      // Arrange
+      const fieldToFind = generateDefaultField(BasicField.Number)
+      // Should not turn this unit test into an integration test, so mocking return and leaving responsibility to mongoose.
+      const mockDocArray = ({
+        0: generateDefaultField(BasicField.LongText),
+        1: fieldToFind,
+        isMongooseDocumentArray: true,
+        id: jest.fn().mockReturnValue(fieldToFind),
+      } as unknown) as Types.DocumentArray<IFieldSchema>
+
+      // Act
+      const result = getFormFieldById(mockDocArray, fieldToFind._id)
+
+      // Assert
+      expect(result).toEqual(fieldToFind)
+      expect(mockDocArray.id).toHaveBeenCalledWith(fieldToFind._id)
+    })
+
+    it('should return null when given form fields are undefined', async () => {
+      // Arrange
+      const someFieldId = new ObjectId()
+
+      // Act
+      const result = getFormFieldById(undefined, someFieldId)
+
+      // Assert
+      expect(result).toEqual(null)
+    })
+
+    it('should return null when no fields correspond to given field id', async () => {
+      // Arrange
+      const invalidFieldId = new ObjectId()
+      const formFields = [
+        generateDefaultField(BasicField.Date),
+        generateDefaultField(BasicField.Date),
+      ]
+
+      // Act
+      const result = getFormFieldById(formFields, invalidFieldId)
+
+      // Assert
+      expect(result).toEqual(null)
+    })
+  })
 })

src/app/modules/form/form.utils.ts

@@ -102,7 +102,7 @@ export const isMongooseDocumentArray = <T extends Document>(
  */
 export const getFormFieldById = (
   formFields: IFormSchema['form_fields'],
-  fieldId: string,
+  fieldId: IFieldSchema['_id'],
 ): IFieldSchema | null => {
   if (!formFields) {
     return null