testsuite.TestUpdateCallback method should be given no-ops when not provided

[mnichols]

Expected Behavior

I should be able to just provide a callback for OnComplete in the testsuite.TestUpdateCallbacks.
Either that, or I should get an error that tells me what is really wrong (not nil pointer).

Actual Behavior

This doesn't seem to check that each callback is provided so will panic when invoked downstream. These nil pointer exceptions are super hard to understand coming out of this test suite and make testing brittle with UpdateWorkflow.

I recommend we either:

1. catch the error and provided a more meaningful error
2. (better) provide no-op stubs when a particular callback is not provided (eg OnAccept: func() {})

Somewhere in here probably:
https://github.com/temporalio/sdk-go/blob/master/internal/internal_workflow_testsuite.go#L2986

Steps to Reproduce the Problem

This will fail because I don't have OnAccept provided as a noop.
IMO this should be an opt-in facility.

package myworkflow

import (
	"fmt"
	"github.com/google/uuid"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"go.temporal.io/sdk/testsuite"
	"go.temporal.io/sdk/workflow"
	"testing"
)

func MyWorkflow(ctx workflow.Context) error {

	if err := workflow.SetUpdateHandler(
		ctx,
		"add",
		func(ctx workflow.Context) (int, error) {
			fmt.Printf("UpdateHandler called")
			return 42, nil
		}); err != nil {

		return fmt.Errorf("could not set update: %w", err)
	}
	return nil
}

func TestUpdateReturnsAppropriateResponse(t *testing.T) {
	A := assert.New(t)
	R := require.New(t)

	s := &testsuite.WorkflowTestSuite{}

	env := s.NewTestWorkflowEnvironment()

	env.RegisterWorkflow(StandaloneScreening)
	env.RegisterDelayedCallback(func() {
		env.UpdateWorkflow("add", uuid.New().String(), &testsuite.TestUpdateCallback{
			//  uncomment this callback to let it pass
                         // OnAccept: func() {},
			OnReject: func(err error) {
				R.NoError(err)
			},
			OnComplete: func(i interface{}, err error) {
				fmt.Printf("OnComplete: %v\n", i)
			},
		})
	}, 0)
	env.ExecuteWorkflow(MyWorkflow)
	err := env.GetWorkflowError()
	R.NoError(err)
	A.True(env.IsWorkflowCompleted())
	A.NoError(env.GetWorkflowError())
}

Specifications

• Version:
• Platform: