Testsuite.TestUpdateCallback Method Should Be Given No-ops When Not Provided

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

Expected Behavior

When using the testsuite.TestUpdateCallbacks in the Temporal SDK, it should be possible to provide a callback for OnComplete without having to provide all other callbacks. Alternatively, the test suite should provide a meaningful error message when a callback is missing, rather than a nil pointer exception.

Actual Behavior

Currently, the testsuite.TestUpdateCallbacks does not check if each callback is provided, which can lead to nil pointer exceptions when the test suite is run. This makes testing brittle and difficult to understand, especially when using the UpdateWorkflow method.

Recommendations

To fix this issue, we can either:

  1. Catch the error and provide a more meaningful error message.
  2. (Better) Provide no-op stubs for callbacks that are not provided, such as OnAccept: func() {}.

Steps to Reproduce the Problem

To reproduce the problem, we can create a test workflow that uses the UpdateWorkflow method without providing all the necessary callbacks. In this example, we will create a test workflow that uses the UpdateWorkflow method without providing the OnAccept callback.

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: Temporal SDK Go
  • Platform: Go
  • Description: The testsuite.TestUpdateCallback method should provide no-op stubs for callbacks that are not provided, rather than panicking with a nil pointer exception.

Solution

To fix this issue, we can modify the testsuite.TestUpdateCallbacks to provide no-op stubs for callbacks that are not provided. We can do this by adding a default implementation for each callback that does nothing.

func (ts *TestUpdateCallbacks) OnAccept() {
	// do nothing
}

func (ts *TestUpdateCallbacks) OnReject(err error) {
	// do nothing
}

func (ts *TestUpdateCallbacks) OnComplete(i interface{}, err error) {
	// do nothing
}

With this change, the testsuite.TestUpdateCallbacks will provide no-op stubs for callbacks that are not provided, rather than panicking with a nil pointer exception.

Benefits

By providing no-op stubs for callbacks that are not provided, we can make the testsuite.TestUpdateCallbacks more robust and easier to use. This will make it easier for developers to write tests for their workflows and reduce the likelihood of nil pointer exceptions.

Conclusion

In conclusion, the testsuite.TestUpdateCallback method should provide no-op stubs for callbacks that are not provided, rather than panicking with a nil pointer exception. By making this change, we can make the testsuite.TestUpdateCallbacks more robust and easier to use, which will make it easier for developers to write tests for their workflows.
Q&A: testsuite.TestUpdateCallback method should be given no-ops when not provided

Q: What is the expected behavior of the testsuite.TestUpdateCallbacks?

A: The expected behavior of the testsuite.TestUpdateCallbacks is that it should be possible to provide a callback for OnComplete without having to provide all other callbacks. Alternatively, the test suite should provide a meaningful error message when a callback is missing, rather than a nil pointer exception.

Q: What is the actual behavior of the testsuite.TestUpdateCallbacks?

A: The actual behavior of the testsuite.TestUpdateCallbacks is that it does not check if each callback is provided, which can lead to nil pointer exceptions when the test suite is run. This makes testing brittle and difficult to understand, especially when using the UpdateWorkflow method.

Q: Why is it a problem to have nil pointer exceptions in the test suite?

A: Nil pointer exceptions in the test suite can make testing brittle and difficult to understand. They can also make it harder to identify the root cause of the issue, which can lead to wasted time and resources.

Q: What are the recommendations for fixing this issue?

A: There are two recommendations for fixing this issue:

  1. Catch the error and provide a more meaningful error message.
  2. (Better) Provide no-op stubs for callbacks that are not provided, such as OnAccept: func() {}.

Q: Why is providing no-op stubs a better solution?

A: Providing no-op stubs is a better solution because it makes the test suite more robust and easier to use. It also reduces the likelihood of nil pointer exceptions, which can make testing more difficult.

Q: How can I implement no-op stubs for callbacks that are not provided?

A: To implement no-op stubs for callbacks that are not provided, you can add a default implementation for each callback that does nothing. For example:

func (ts *TestUpdateCallbacks) OnAccept() {
	// do nothing
}

func (ts *TestUpdateCallbacks) OnReject(err error) {
	// do nothing
}

func (ts *TestUpdateCallbacks) OnComplete(i interface{}, err error) {
	// do nothing
}

Q: What are the benefits of providing no-op stubs for callbacks that are not provided?

A: The benefits of providing no-op stubs for callbacks that are not provided include:

  • Making the test suite more robust and easier to use
  • Reducing the likelihood of nil pointer exceptions
  • Making it easier to identify the root cause of issues

Q: How can I use the testsuite.TestUpdateCallbacks with no-op stubs?

A: To use the testsuite.TestUpdateCallbacks with no-op stubs, you can create a test workflow that uses the UpdateWorkflow method without providing all the necessary callbacks. For example:

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())
}

Q: What are the specifications for this solution?

A: The specifications for this solution are:

  • Version: Temporal SDK Go
  • Platform: Go
  • Description: The testsuite.TestUpdateCallback method should provide no-op stubs for callbacks that are not provided, rather than panicking with a nil pointer exception.