Add cancel option to form wizard

This adds a cancel url local that can be used by the template to
the form wizard so that the form journey can be cancelled by the user.

app/move/controllers/new.form.js

@@ -10,6 +10,16 @@ class FormController extends Controller {
     this.use(this.checkCurrentLocation)
   }
 
+  middlewareLocals() {
+    super.middlewareLocals()
+    this.use(this.setCancelUrl)
+  }
+
+  setCancelUrl(req, res, next) {
+    res.locals.cancelUrl = `/moves${res.locals.MOVES_QUERY_STRING || ''}`
+    next()
+  }
+
   checkCurrentLocation(req, res, next) {
     if (!req.session.currentLocation) {
       const error = new Error(

app/move/controllers/new.form.test.js

@@ -28,6 +28,66 @@ describe('Move controllers', function() {
       })
     })
 
+    describe('#middlewareLocals()', function() {
+      beforeEach(function() {
+        sinon.stub(FormController.prototype, 'middlewareLocals')
+        sinon.stub(controller, 'use')
+
+        controller.middlewareLocals()
+      })
+
+      it('should call parent method', function() {
+        expect(FormController.prototype.middlewareLocals).to.have.been
+          .calledOnce
+      })
+
+      it('should call set cancel url method', function() {
+        expect(controller.use).to.have.been.calledWith(controller.setCancelUrl)
+      })
+    })
+
+    describe('#setCancelUrl()', function() {
+      let res, nextSpy
+
+      beforeEach(function() {
+        nextSpy = sinon.spy()
+        res = {
+          locals: {},
+        }
+      })
+
+      context('with empty moves query', function() {
+        beforeEach(function() {
+          controller.setCancelUrl({}, res, nextSpy)
+        })
+
+        it('should set cancel url correctly', function() {
+          expect(res.locals).to.have.property('cancelUrl')
+          expect(res.locals.cancelUrl).to.equal('/moves')
+        })
+
+        it('should call next', function() {
+          expect(nextSpy).to.be.calledOnceWithExactly()
+        })
+      })
+
+      context('with moves query', function() {
+        beforeEach(function() {
+          res.locals.MOVES_QUERY_STRING = '?move-date=2019-10-10'
+          controller.setCancelUrl({}, res, nextSpy)
+        })
+
+        it('should set cancel url correctly', function() {
+          expect(res.locals).to.have.property('cancelUrl')
+          expect(res.locals.cancelUrl).to.equal('/moves?move-date=2019-10-10')
+        })
+
+        it('should call next', function() {
+          expect(nextSpy).to.be.calledOnceWithExactly()
+        })
+      })
+    })
+
     describe('#checkCurrentLocation()', function() {
       let req, nextSpy
 

common/templates/form-wizard.njk

@@ -47,5 +47,9 @@
     {{ govukButton({
       text: t(options.buttonText or "actions::continue")
     }) }}
+
+    {% if cancelUrl %}
+      <a href="{{ cancelUrl }}" class="govuk-button govuk-button--text">Cancel</a>
+    {% endif %}
   </form>
 {% endblock %}