From 94d0bd53433d88d2e4c3b9e952587b14f44ce166 Mon Sep 17 00:00:00 2001
From: Shaun Cooley <scooley@mapped.com>
Date: Sat, 20 Nov 2021 15:13:40 -0800
Subject: [PATCH 1/2] fix: handling of nil passed as an arg to a typed
 interface parameter for #160

---
 handler.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/handler.go b/handler.go
index 783823a..aec375f 100644
--- a/handler.go
+++ b/handler.go
@@ -104,7 +104,11 @@ func (h *reflectFunc) fnArgs(msg *Message) ([]reflect.Value, error) {
 			inType := h.ft.In(inStart + i)
 
 			if inType.Kind() == reflect.Interface {
-				if !v.Type().Implements(inType) {
+				// If the input value is an untyped nil, simply create a new
+				// typed nil so that the subsequent .Call() works
+				if !v.IsValid() {
+					v = reflect.Zero(inType)
+				} else if !v.Type().Implements(inType) {
 					hasWrongType = true
 					break
 				}

From ffdc989d3511c7005e0b7c717c0f6a7f1ba8fe2f Mon Sep 17 00:00:00 2001
From: Shaun Cooley <scooley@mapped.com>
Date: Fri, 26 Nov 2021 10:59:21 -0800
Subject: [PATCH 2/2] Unit test for interface args on memqueue

---
 memqueue/memqueue_test.go | 45 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/memqueue/memqueue_test.go b/memqueue/memqueue_test.go
index 5b3876e..01bc8c0 100644
--- a/memqueue/memqueue_test.go
+++ b/memqueue/memqueue_test.go
@@ -62,6 +62,51 @@ var _ = Describe("message with args", func() {
 	})
 })
 
+type testInterface interface {
+	TestFunction() int
+}
+
+type testInterfaceImpl struct {
+	x int
+}
+
+func (t *testInterfaceImpl) TestFunction() int {
+	return t.x
+}
+
+var _ = Describe("message with interface args", func() {
+	ctx := context.Background()
+	ch := make(chan bool, 10)
+
+	BeforeEach(func() {
+		q := memqueue.NewQueue(&taskq.QueueOptions{
+			Name:    "test",
+			Storage: taskq.NewLocalStorage(),
+		})
+		expected := 7
+		task := taskq.RegisterTask(&taskq.TaskOptions{
+			Name: "test",
+			Handler: func(notNilArg testInterface, nilArg testInterface) {
+				Expect(notNilArg).ToNot(BeNil())
+				Expect(nilArg).To(BeNil())
+				Expect(notNilArg.TestFunction()).To(Equal(expected))
+				ch <- true
+			},
+		})
+		notNilInput := testInterface(&testInterfaceImpl{x: expected})
+		err := q.Add(task.WithArgs(ctx, notNilInput, nil))
+		Expect(err).NotTo(HaveOccurred())
+
+		err = q.Close()
+		Expect(err).NotTo(HaveOccurred())
+	})
+
+	It("handler is called with args", func() {
+		Expect(ch).To(Receive())
+		Expect(ch).NotTo(Receive())
+	})
+})
+
 var _ = Describe("context.Context", func() {
 	ctx := context.Background()
 	ch := make(chan bool, 10)