Add a few testing conveniences (#9447)

## What changed?
- Add AdminClient to testcore.Env interface
- Add taskpoller.CompleteWorkflowHandler - simple handler to always
complete a workflow
- Add metricstest.CaptureSnapshot type alias - this makes it easier to
pass snapshots to helper functions

## Why?
Make tests easier to write.

## How did you test it?
- [ ] built
- [x] run locally and tested manually
- [ ] covered by existing tests
- [ ] added new unit test(s)
- [x] added new functional test(s) - these are used by functional tests
to be sent in future PRs

common/metrics/metricstest/capture_handler.go

@@ -1,6 +1,8 @@
 package metricstest
 
 import (
+	"maps"
+	"slices"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -18,19 +20,19 @@ type CapturedRecording struct {
 
 // Capture is a specific capture instance.
 type Capture struct {
-	recordings     map[string][]*CapturedRecording
+	recordings     CaptureSnapshot
 	recordingsLock sync.RWMutex
 }
 
+type CaptureSnapshot = map[string][]*CapturedRecording
+
 // Snapshot returns a copy of all metrics recorded, keyed by name.
-func (c *Capture) Snapshot() map[string][]*CapturedRecording {
+func (c *Capture) Snapshot() CaptureSnapshot {
 	c.recordingsLock.RLock()
 	defer c.recordingsLock.RUnlock()
-	ret := make(map[string][]*CapturedRecording, len(c.recordings))
-	for k, v := range c.recordings {
-		recs := make([]*CapturedRecording, len(v))
-		copy(recs, v)
-		ret[k] = recs
+	ret := maps.Clone(c.recordings)
+	for k, v := range ret {
+		ret[k] = slices.Clone(v)
 	}
 	return ret
 }
@@ -63,7 +65,7 @@ func NewCaptureHandler() *CaptureHandler {
 // StartCapture returns a started capture. StopCapture should be called on
 // complete.
 func (c *CaptureHandler) StartCapture() *Capture {
-	capture := &Capture{recordings: map[string][]*CapturedRecording{}}
+	capture := &Capture{recordings: make(CaptureSnapshot)}
 	c.capturesLock.Lock()
 	defer c.capturesLock.Unlock()
 

common/testing/taskpoller/taskpoller.go

@@ -9,6 +9,7 @@ import (
 	"github.com/nexus-rpc/sdk-go/nexus"
 	nexuspb "go.temporal.io/api/nexus/v1"
 
+	commandpb "go.temporal.io/api/command/v1"
 	enumspb "go.temporal.io/api/enums/v1"
 	failurepb "go.temporal.io/api/failure/v1"
 	historypb "go.temporal.io/api/history/v1"
@@ -55,6 +56,17 @@ var (
 	DrainWorkflowTask = func(task *workflowservice.PollWorkflowTaskQueueResponse) (*workflowservice.RespondWorkflowTaskCompletedRequest, error) {
 		return &workflowservice.RespondWorkflowTaskCompletedRequest{}, nil
 	}
+	// CompleteWorkflowHandler is a workflow task handler that always completes the workflow.
+	CompleteWorkflowHandler = func(task *workflowservice.PollWorkflowTaskQueueResponse) (*workflowservice.RespondWorkflowTaskCompletedRequest, error) {
+		return &workflowservice.RespondWorkflowTaskCompletedRequest{
+			Commands: []*commandpb.Command{{
+				CommandType: enumspb.COMMAND_TYPE_COMPLETE_WORKFLOW_EXECUTION,
+				Attributes: &commandpb.Command_CompleteWorkflowExecutionCommandAttributes{
+					CompleteWorkflowExecutionCommandAttributes: &commandpb.CompleteWorkflowExecutionCommandAttributes{},
+				},
+			}},
+		}, nil
+	}
 	// CompleteActivityTask returns a RespondActivityTaskCompletedRequest with an auto-generated `Result` from `tv.Any().Payloads()`.
 	CompleteActivityTask = func(tv *testvars.TestVars) func(task *workflowservice.PollActivityTaskQueueResponse) (*workflowservice.RespondActivityTaskCompletedRequest, error) {
 		return func(task *workflowservice.PollActivityTaskQueueResponse) (*workflowservice.RespondActivityTaskCompletedRequest, error) {

tests/testcore/test_env.go

@@ -17,6 +17,7 @@ import (
 	"go.temporal.io/api/workflowservice/v1"
 	sdkclient "go.temporal.io/sdk/client"
 	sdkworker "go.temporal.io/sdk/worker"
+	"go.temporal.io/server/api/adminservice/v1"
 	"go.temporal.io/server/common/debug"
 	"go.temporal.io/server/common/dynamicconfig"
 	"go.temporal.io/server/common/log"
@@ -45,6 +46,7 @@ type Env interface {
 	Namespace() namespace.Name
 	NamespaceID() namespace.ID
 	FrontendClient() workflowservice.WorkflowServiceClient
+	AdminClient() adminservice.AdminServiceClient
 	GetTestCluster() *TestCluster
 	CloseShard(namespaceID string, workflowID string)
 	OverrideDynamicConfig(setting dynamicconfig.GenericSetting, value any) (cleanup func())