Export SetContinuedAsNewRunID in the TestWorkflowEnvironment

When building "actor" workflows, you sometimes want to be able to
distinguish when a workflow is starting and when it's being continued as
new. This allows you to execute different behavior like restoring some
state from an external system.

One way to check if your current workflow execution has been continued
as new is to inspect the workflow info ContinuedAsNewRunID field. When
it's set, then you now you are not starting fresh.

When testing such workflows though, you may want to test behavior only
after a first ContinueAsNew call. The easiest way to do that is to
setup the test environment to fill up the workflow info
ContinuedAsNewRunID field.

This is what this commit is doing, it extends the
TestWorkflowEnvironment to expose a SetContinuedExecutionID field to an
arbitrary value.

This way in workflow unit tests, we can skip the code paths we don't
care about and don't resort to mocking activities and child workflows
for nothing leading to easier to implement and easier to read tests.

internal/internal_workflow_testsuite.go

@@ -353,6 +353,10 @@ func (env *testWorkflowEnvironmentImpl) setContinueAsNewSuggested(suggest bool)
 	env.workflowInfo.continueAsNewSuggested = suggest
 }
 
+func (env *testWorkflowEnvironmentImpl) setContinuedExecutionID(rid string) {
+	env.workflowInfo.ContinuedExecutionRunID = rid
+}
+
 func (env *testWorkflowEnvironmentImpl) newTestWorkflowEnvironmentForChild(params *ExecuteWorkflowParams, callback ResultHandler, startedHandler func(r WorkflowExecution, e error)) (*testWorkflowEnvironmentImpl, error) {
 	// create a new test env
 	childEnv := newTestWorkflowEnvironmentImpl(env.testSuite, env.registry)

internal/internal_workflow_testsuite_test.go

@@ -3747,6 +3747,12 @@ func (s *WorkflowTestSuiteUnitTest) Test_SetWorkerStopChannel() {
 	s.NotNil(env.workerStopChannel)
 }
 
+func (s *WorkflowTestSuiteUnitTest) Test_SetContinuedExecutionRunID() {
+	env := newTestWorkflowEnvironmentImpl(&s.WorkflowTestSuite, nil)
+	env.setContinuedExecutionID("some-run-id")
+	s.NotNil(env.workflowInfo.ContinuedExecutionRunID)
+}
+
 func (s *WorkflowTestSuiteUnitTest) Test_ActivityTimeoutWithDetails() {
 	count := 0
 	timeoutFn := func() error {

internal/workflow_testsuite.go

@@ -318,6 +318,12 @@ func (e *TestWorkflowEnvironment) SetContinueAsNewSuggested(suggest bool) {
 	e.impl.setContinueAsNewSuggested(suggest)
 }
 
+// SetContinuedExecutionID sets the value that is returned from
+// GetInfo(ctx).ContinuedExecutionRunID
+func (e *TestWorkflowEnvironment) SetContinuedAsNewRunID(rid string) {
+	e.impl.setContinuedExecutionID(rid)
+}
+
 // OnActivity setup a mock call for activity. Parameter activity must be activity function (func) or activity name (string).
 // You must call Return() with appropriate parameters on the returned *MockCallWrapper instance. The supplied parameters to
 // the Return() call should either be a function that has exact same signature as the mocked activity, or it should be