Address review comments

client/client.go

@@ -37,7 +37,6 @@ import (
 	enumspb "go.temporal.io/api/enums/v1"
 	historypb "go.temporal.io/api/history/v1"
 	"go.temporal.io/api/operatorservice/v1"
-	"go.temporal.io/api/temporalproto"
 	"go.temporal.io/api/workflowservice/v1"
 
 	"go.temporal.io/sdk/converter"
@@ -750,23 +749,5 @@ type HistoryJSONOptions struct {
 // HistoryFromJSON deserializes history from a reader of JSON bytes. This does
 // not close the reader if it is closeable.
 func HistoryFromJSON(r io.Reader, options HistoryJSONOptions) (*historypb.History, error) {
-	hist := &historypb.History{}
-	// We set DiscardUnknown here because the history may have been created by a previous
-	// version of our protos
-	dec := temporalproto.NewJSONDecoder(r, true)
-	if err := dec.Decode(hist); err != nil {
-		return nil, err
-	}
-
-	// If there is a last event ID, slice the rest off
-	if options.LastEventID > 0 {
-		for i, event := range hist.Events {
-			if event.EventId == options.LastEventID {
-				// Inclusive
-				hist.Events = hist.Events[:i+1]
-				break
-			}
-		}
-	}
-	return hist, nil
+	return internal.HistoryFromJSON(r, options.LastEventID)
 }

internal/internal_worker.go

@@ -222,6 +222,12 @@ type (
 
 		capabilities *workflowservice.GetSystemInfoResponse_Capabilities
 	}
+
+	// HistoryJSONOptions are options for HistoryFromJSON.
+	HistoryJSONOptions struct {
+		// LastEventID, if set, will only load history up to this ID (inclusive).
+		LastEventID int64
+	}
 )
 
 var debugMode = os.Getenv("TEMPORAL_DEBUG") != ""
@@ -1421,6 +1427,30 @@ func (aw *WorkflowReplayer) replayWorkflowHistory(logger log.Logger, service wor
 	return fmt.Errorf("replay workflow doesn't return the same result as the last event, resp: %[1]T{%[1]v}, last: %[2]T{%[2]v}", resp, resp, last)
 }
 
+// HistoryFromJSON deserializes history from a reader of JSON bytes. This does
+// not close the reader if it is closeable.
+func HistoryFromJSON(r io.Reader, lastEventID int64) (*historypb.History, error) {
+	hist := &historypb.History{}
+	// We set DiscardUnknown here because the history may have been created by a previous
+	// version of our protos
+	dec := temporalproto.NewJSONDecoder(r, true)
+	if err := dec.Decode(hist); err != nil {
+		return nil, err
+	}
+
+	// If there is a last event ID, slice the rest off
+	if lastEventID > 0 {
+		for i, event := range hist.Events {
+			if event.EventId == lastEventID {
+				// Inclusive
+				hist.Events = hist.Events[:i+1]
+				break
+			}
+		}
+	}
+	return hist, nil
+}
+
 func extractHistoryFromFile(jsonfileName string, lastEventID int64) (*historypb.History, error) {
 	reader, err := os.Open(jsonfileName)
 	if err != nil {

internal/internal_worker_test.go

@@ -2789,6 +2789,24 @@ func TestWorkerBuildIDAndSessionPanic(t *testing.T) {
 	require.Equal(t, "cannot set both EnableSessionWorker and UseBuildIDForVersioning", recovered)
 }
 
+func TestHistoryFromJSON(t *testing.T) {
+	// Load sample history and just make sure it has the right event count
+	r, err := os.Open("testdata/sampleHistory.json")
+	require.NoError(t, err)
+	hist, err := HistoryFromJSON(r, 0)
+	require.NoError(t, err)
+	require.NoError(t, r.Close())
+	require.Len(t, hist.Events, 11)
+
+	// Only load up through event 5 and confirm
+	r, err = os.Open("testdata/sampleHistory.json")
+	require.NoError(t, err)
+	hist, err = HistoryFromJSON(r, 5)
+	require.NoError(t, err)
+	require.NoError(t, r.Close())
+	require.Len(t, hist.Events, 5)
+}
+
 func aliasNameClash1(context.Context) (string, error) { return "func1", nil }
 func aliasNameClash2(context.Context) (string, error) { return "func2", nil }