Fix off-by-one error in fulfillment code

order/activities.go

@@ -45,7 +45,7 @@ func (a *Activities) FulfillOrder(ctx context.Context, input FulfillOrderInput)
 			fulfillments,
 			Fulfillment{
 				Location: "Warehouse B",
-				Items:    input.Items[1 : len(input.Items)-1],
+				Items:    input.Items[1 : len(input.Items)],
 			},
 		)
 	}

order/activities_test.go

@@ -0,0 +1,85 @@
+package order_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/temporalio/orders-reference-app-go/order"
+	"go.temporal.io/sdk/testsuite"
+)
+
+func TestFulfillOrderOneItem(t *testing.T) {
+	testSuite := testsuite.WorkflowTestSuite{}
+
+	var a *order.Activities
+
+	env := testSuite.NewTestActivityEnvironment()
+	env.RegisterActivity(a.FulfillOrder)
+
+	input := order.FulfillOrderInput{
+		Items: []order.Item{
+			{SKU: "Hiking Boots", Quantity: 2},
+		},
+	}
+
+	future, err := env.ExecuteActivity(a.FulfillOrder, input)
+	require.NoError(t, err)
+
+	var result order.FulfillOrderResult
+	require.NoError(t, future.Get(&result))
+
+	fulfillments := result.Fulfillments
+	require.Equal(t, 1, len(fulfillments))
+
+	fulfillment := fulfillments[0]
+	require.Equal(t, "Warehouse A", fulfillment.Location)
+
+	require.Equal(t, 1, len(fulfillment.Items))
+
+	item := fulfillment.Items[0]
+	require.Equal(t, "Hiking Boots", item.SKU)
+	require.Equal(t, int32(2), item.Quantity)
+}
+
+func TestFulfillOrderTwoItems(t *testing.T) {
+	testSuite := testsuite.WorkflowTestSuite{}
+
+	var a *order.Activities
+
+	env := testSuite.NewTestActivityEnvironment()
+	env.RegisterActivity(a.FulfillOrder)
+
+	input := order.FulfillOrderInput{
+		Items: []order.Item{
+			{SKU: "Hiking Boots", Quantity: 2},
+			{SKU: "Tennis Shoes", Quantity: 1},
+		},
+	}
+
+	future, err := env.ExecuteActivity(a.FulfillOrder, input)
+	require.NoError(t, err)
+
+	var result order.FulfillOrderResult
+	require.NoError(t, future.Get(&result))
+
+	fulfillments := result.Fulfillments
+	require.Equal(t, 2, len(fulfillments))
+
+	fulfillmentA := fulfillments[0]
+	require.Equal(t, "Warehouse A", fulfillmentA.Location)
+
+	require.Equal(t, 1, len(fulfillmentA.Items))
+
+	itemOne := fulfillmentA.Items[0]
+	require.Equal(t, "Hiking Boots", itemOne.SKU)
+	require.Equal(t, int32(2), itemOne.Quantity)
+
+	fulfillmentB := fulfillments[1]
+	require.Equal(t, "Warehouse B", fulfillmentB.Location)
+
+	require.Equal(t, 1, len(fulfillmentB.Items))
+
+	itemTwo := fulfillmentB.Items[0]
+	require.Equal(t, "Tennis Shoes", itemTwo.SKU)
+	require.Equal(t, int32(1), itemTwo.Quantity)
+}