Handles missing payment via PaymentField state validation

Author: jbarnsley10

src/server/forms/payment-test.yaml

@@ -3,6 +3,17 @@ schema: 2
 name: Payment Test Form
 declaration: "<p class=\"govuk-body\">All the answers you have provided are true to the best of your knowledge.</p>"
 pages:
+  - title: What is your name?
+    path: '/person'
+    components:
+      - name: personName
+        title: What is your name?
+        type: TextField
+        shortDescription: Your name
+        options:
+          required: true
+    next:
+      - path: '/pay-for-your-licence'
   - title: A page title
     path: '/pay-for-your-licence'
     components:
@@ -28,4 +39,4 @@ pages:
 conditions: []
 sections: []
 lists: []
-startPage: '/pay-for-your-licence'
+startPage: '/person'

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

@@ -68,7 +68,10 @@ export class PaymentField extends FormComponent {
       .label(this.label)
 
     this.formSchema = paymentStateSchema
-    this.stateSchema = paymentStateSchema.default(null).allow(null)
+    // 'required()' forces the payment page to be invalid until we have valid payment state
+    // i.e. the user will automatically be directed back to the payment page
+    // if they attempt to access future pages wen no payment entered yet
+    this.stateSchema = paymentStateSchema.required()
   }
 
   /**

src/server/plugins/engine/models/FormModel.ts

@@ -29,7 +29,6 @@ import { Parser, type Value } from 'expr-eval-fork'
 import joi from 'joi'
 
 import { createLogger } from '~/src/server/common/helpers/logging/logger.js'
-import { type ComponentCollection } from '~/src/server/plugins/engine/components/ComponentCollection.js'
 import { type ListFormComponent } from '~/src/server/plugins/engine/components/ListFormComponent.js'
 import {} from '~/src/server/plugins/engine/components/YesNoField.js'
 import {
@@ -521,30 +520,15 @@ export class FormModel {
     }
   }
 
-  private isUnpaidPayment(
-    context: FormContext,
-    collection: ComponentCollection
-  ) {
-    const paymentField = collection.fields.find(
-      (field) => field.type === ComponentType.PaymentField
-    )
-    if (paymentField) {
-      const fieldVal = paymentField.getFormValueFromState(context.state)
-      return fieldVal === undefined
-    }
-    return false
-  }
-
   private assignPaths(context: FormContext) {
-    for (const { keys, path, collection } of context.relevantPages) {
+    for (const { keys, path } of context.relevantPages) {
       context.paths.push(path)
 
       // Stop at page with errors
       if (
         context.errors?.some(({ name, path }) => {
           return keys.includes(name) || keys.some((key) => path.includes(key))
-        }) ||
-        this.isUnpaidPayment(context, collection)
+        })
       ) {
         break
       }