Support testing activities

Author: cschleiden

README.md

@@ -486,6 +486,8 @@ workflow.Select(
 
 ### Unit testing
 
+#### Workflows
+
 go-workflows includes support for testing workflows, a simple example using mocked activities:
 
 ```go
@@ -514,6 +516,27 @@ func TestWorkflow(t *testing.T) {
 - Timers are automatically fired by advancing a mock workflow clock that is used for testing workflows
 - You can register callbacks to fire at specific times (in mock-clock time). Callbacks can send signals, cancel workflows etc.
 
+#### Activities
+
+Activities can be tested like any other function. If you make use of
+
+
+```go
+func Activity(ctx context.Context, a int, b int) (int, error) {
+	activity.Logger(ctx).Debug("Activity is called", "a", a)
+
+	return a + b, nil
+}
+
+func TestActivity(t *testing.T) {
+	ctx := activitytester.WithActivityTestState(context.Background(), "activityID", "instanceID", nil)
+
+	r, err := Activity(ctx, 35, 12)
+	require.Equal(t, 47, r)
+	require.NoError(t, err)
+}
+```
+
 ### Logging
 
 For logging, you can pass a type to the backend via the `WithLogger` option to set a custom logger. The type has to implement this simple interface:

activitytester/activitytester.go

@@ -0,0 +1,18 @@
+package activitytester
+
+import (
+	"context"
+
+	"github.com/cschleiden/go-workflows/internal/activity"
+	"github.com/cschleiden/go-workflows/internal/core"
+	dlogger "github.com/cschleiden/go-workflows/internal/logger"
+	"github.com/cschleiden/go-workflows/log"
+)
+
+func WithActivityTestState(ctx context.Context, activityID, instanceID string, logger log.Logger) context.Context {
+	if logger == nil {
+		logger = dlogger.NewDefaultLogger()
+	}
+
+	return activity.WithActivityState(ctx, activity.NewActivityState(activityID, core.NewWorkflowInstance(instanceID, ""), logger))
+}

activitytester/activitytester_test.go

@@ -0,0 +1,23 @@
+package activitytester
+
+import (
+	"context"
+	"testing"
+
+	"github.com/cschleiden/go-workflows/activity"
+	"github.com/stretchr/testify/require"
+)
+
+func Activity(ctx context.Context, a int, b int) (int, error) {
+	activity.Logger(ctx).Debug("Activity is called", "a", a)
+
+	return a + b, nil
+}
+
+func TestActivityTester(t *testing.T) {
+	ctx := WithActivityTestState(context.Background(), "activityID", "instanceID", nil)
+
+	r, err := Activity(ctx, 35, 12)
+	require.Equal(t, 47, r)
+	require.NoError(t, err)
+}

tester/tester_activity_test.go

@@ -1,9 +1,11 @@
 package tester
 
 import (
+	"context"
 	"testing"
 	"time"
 
+	"github.com/cschleiden/go-workflows/activity"
 	"github.com/cschleiden/go-workflows/workflow"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
@@ -103,3 +105,26 @@ func Test_ActivityRaceWithSignal(t *testing.T) {
 	require.Equal(t, "signal", wr)
 	tester.AssertExpectations(t)
 }
+
+func Test_ActivityWithLogger(t *testing.T) {
+	activity1 := func(ctx context.Context) (string, error) {
+		activity.Logger(ctx).Debug("hello from test")
+
+		return "activity", nil
+	}
+
+	wf := func(ctx workflow.Context) error {
+		workflow.ExecuteActivity[string](ctx, workflow.DefaultActivityOptions, activity1).Get(ctx)
+
+		return nil
+	}
+
+	tester := NewWorkflowTester[string](wf, WithTestTimeout(time.Second*3))
+
+	tester.Registry().RegisterActivity(activity1)
+
+	tester.Execute()
+
+	require.True(t, tester.WorkflowFinished())
+	tester.AssertExpectations(t)
+}