(DO NOT MERGE) Fix workflow registration alias handling in the test environment

CHANGELOG.md

@@ -68,6 +68,16 @@ to docs, or any other relevant information.
 
 ### Fixed
 
+- Changed how test suites resolve workflow types for `ExecuteWorkflow` and `ExecuteChildWorkflow` when
+  registration aliasing is enabled (the default). Previously, implementation lookup used the workflow
+  type directly; it now performs an additional alias lookup, matching production workers. If `WorkflowA`
+  is registered as `"WorkflowB"` and `WorkflowB` as `"WorkflowC"`, executing `"WorkflowB"` now runs
+  function `WorkflowB` instead of `WorkflowA`. This unintuitive behavior brings test execution in line
+  with production.
+- Fixed how `TestWorkflowEnvironment.OnWorkflow` resolves workflow types when registration aliasing is
+  enabled. If your test suite registered workflow `WorkflowA` as `"WorkflowB"` and registered `WorkflowB`
+  under another name, `OnWorkflow(WorkflowA, ...)` could incorrectly install the mock under that second
+  name. It now installs the mock under `"WorkflowB"`.
 - Local activity mock lookup in `TestWorkflowEnvironment` no longer tries re-resolving the activity name.
   This fixes a bug where two closures with different registered names would alias each other.
 - mTLS client setup and schedule creation no longer modify caller-owned TLS

internal/internal_workflow_testsuite.go

@@ -835,10 +835,14 @@ func (env *testWorkflowEnvironmentImpl) executeWorkflowInternal(delayStart time.
 }
 
 func (env *testWorkflowEnvironmentImpl) getWorkflowDefinition(wt WorkflowType) (WorkflowDefinition, error) {
-	wf, ok := env.registry.getWorkflowFn(wt.Name)
+	lookup := wt.Name
+	if alias, ok := env.registry.getWorkflowAlias(lookup); ok {
+		lookup = alias
+	}
+	wf, ok := env.registry.getWorkflowFn(lookup)
 	if !ok {
 		supported := strings.Join(env.registry.getRegisteredWorkflowTypes(), ", ")
-		return nil, fmt.Errorf("unable to find workflow type: %v. Supported types: [%v]", wt.Name, supported)
+		return nil, fmt.Errorf("unable to find workflow type: %v. Supported types: [%v]", lookup, supported)
 	}
 	var dynamic bool
 	if d, ok := wf.(string); ok && d == "dynamic" {

internal/workflow_testsuite.go

@@ -514,9 +514,6 @@ func (e *TestWorkflowEnvironment) OnWorkflow(workflow any, args ...any) *MockCal
 			panic(err)
 		}
 		fnName, _ := GetWorkflowFunctionName(e.impl.registry, workflow)
-		if alias, ok := e.impl.registry.getWorkflowAlias(fnName); ok {
-			fnName = alias
-		}
 		e.impl.registry.RegisterWorkflowWithOptions(workflow, RegisterWorkflowOptions{DisableAlreadyRegisteredCheck: true})
 		call = e.workflowMock.On(fnName, args...)
 	case reflect.String: