DF-951: MonthYearField to support absolute date range options

package.json

@@ -87,7 +87,7 @@
   },
   "license": "SEE LICENSE IN LICENSE",
   "dependencies": {
-    "@defra/forms-model": "^3.0.676",
+    "@defra/forms-model": "^3.0.678",
     "@defra/hapi-tracing": "^1.29.0",
     "@defra/interactive-map": "^0.0.22-alpha",
     "@elastic/ecs-pino-format": "^1.5.0",

src/server/plugins/engine/components/MonthYearField.test.ts

@@ -1,5 +1,5 @@
 import { ComponentType, type MonthYearFieldComponent } from '@defra/forms-model'
-import { startOfDay } from 'date-fns'
+import { addMonths, format, startOfDay, startOfMonth } from 'date-fns'
 
 import { ComponentCollection } from '~/src/server/plugins/engine/components/ComponentCollection.js'
 import {
@@ -401,6 +401,13 @@ describe('MonthYearField', () => {
 
   describe('Validation', () => {
     const date = new Date('2001-01-01')
+    const today = startOfDay(new Date())
+    const thisMonth = startOfMonth(today)
+
+    const OneMonthInPast = addMonths(thisMonth, -1)
+    const TwoMonthsInPast = addMonths(thisMonth, -2)
+    const OneMonthInFuture = addMonths(thisMonth, 1)
+    const TwoMonthsInFuture = addMonths(thisMonth, 2)
 
     describe.each([
       {
@@ -517,6 +524,62 @@ describe('MonthYearField', () => {
           }
         ]
       },
+      {
+        description: 'Earliest month/year option',
+        component: {
+          title: 'Example month/year field',
+          name: 'myComponent',
+          type: ComponentType.MonthYearField,
+          options: {
+            earliestMonthYear: format(OneMonthInPast, 'yyyy-MM')
+          }
+        } satisfies MonthYearFieldComponent,
+        assertions: [
+          {
+            input: getFormData(TwoMonthsInPast),
+            output: {
+              value: getFormData(TwoMonthsInPast),
+              errors: [
+                expect.objectContaining({
+                  text: `Example month/year field must be the same as or after ${format(OneMonthInPast, 'd MMMM yyyy')}`
+                })
+              ]
+            }
+          },
+          {
+            input: getFormData(today),
+            output: { value: getFormData(today) }
+          }
+        ]
+      },
+      {
+        description: 'Latest month/year option',
+        component: {
+          title: 'Example month/year field',
+          name: 'myComponent',
+          type: ComponentType.MonthYearField,
+          options: {
+            latestMonthYear: format(OneMonthInFuture, 'yyyy-MM')
+          }
+        } satisfies MonthYearFieldComponent,
+        assertions: [
+          {
+            input: getFormData(TwoMonthsInFuture),
+            output: {
+              value: getFormData(TwoMonthsInFuture),
+              errors: [
+                expect.objectContaining({
+                  text: `Example month/year field must be the same as or before ${format(OneMonthInFuture, 'd MMMM yyyy')}`
+                })
+              ]
+            }
+          },
+          {
+            input: getFormData(today),
+            output: { value: getFormData(today) }
+          }
+        ]
+      },
       {
         description: 'Optional fields',
         component: {

src/server/plugins/engine/components/MonthYearField.ts

@@ -1,5 +1,5 @@
 import { ComponentType, type MonthYearFieldComponent } from '@defra/forms-model'
-import { format, isValid } from 'date-fns'
+import { format, isValid, parse } from 'date-fns'
 import {
   type Context,
   type CustomValidator,
@@ -259,6 +259,34 @@ export function getValidatorMonthYear(component: MonthYearField) {
         : payload
     }
 
+    const date = parse(
+      `${values.year}-${values.month}-01`,
+      'yyyy-MM-dd',
+      new Date()
+    )
+
+    if (!isValid(date)) {
+      return helpers.error('date.format', context)
+    }
+
+    // Minimum date from today
+    const earliestDate = options.earliestMonthYear
+      ? new Date(`${options.earliestMonthYear}-01`)
+      : undefined
+
+    if (earliestDate && date < earliestDate) {
+      return helpers.error('date.min', { ...context, limit: earliestDate })
+    }
+
+    // Maximum date from today
+    const latestDate = options.latestMonthYear
+      ? new Date(`${options.latestMonthYear}-01`)
+      : undefined
+
+    if (latestDate && date > latestDate) {
+      return helpers.error('date.max', { ...context, limit: latestDate })
+    }
+
     return payload
   }