From 3f509196b91304e7d618542d5894a17fe7fd98a5 Mon Sep 17 00:00:00 2001
From: Copilot <223556219+Copilot@users.noreply.github.com>
Date: Fri, 13 Mar 2026 02:55:29 +0000
Subject: [PATCH] fix: move activity input JSON.parse inside try-catch for
 proper error handling
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The JSON.parse call for deserializing activity input was positioned outside
the try-catch block in ActivityExecutor.execute(). When encodedInput contained
malformed JSON, the SyntaxError bypassed the activityFailed log (EventId 605)
and propagated with no activity context (name, orchestrationId).

Move JSON.parse inside the existing try-catch so all activity execution
failures — including input deserialization errors — are logged consistently
and re-thrown with proper context.

Add unit tests for malformed JSON input, undefined input, and empty string
input edge cases.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 .../src/worker/activity-executor.ts           |  6 ++-
 .../test/activity_executor.spec.ts            | 54 ++++++++++++++++++-
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/packages/durabletask-js/src/worker/activity-executor.ts b/packages/durabletask-js/src/worker/activity-executor.ts
index 10ba9a9..f4ad151 100644
--- a/packages/durabletask-js/src/worker/activity-executor.ts
+++ b/packages/durabletask-js/src/worker/activity-executor.ts
@@ -32,10 +32,14 @@ export class ActivityExecutor {
     // Log activity start (EventId 603)
     WorkerLogs.activityStarted(this._logger, orchestrationId, name);
 
-    const activityInput = encodedInput ? JSON.parse(encodedInput) : undefined;
     const ctx = new ActivityContext(orchestrationId, taskId);
 
     try {
+      // Deserialize the input inside the try-catch so that malformed JSON
+      // is reported through the same activityFailed log path (EventId 605)
+      // as any other activity execution error.
+      const activityInput = encodedInput ? JSON.parse(encodedInput) : undefined;
+
       // Execute the activity function
       let activityOutput = fn(ctx, activityInput);
 
diff --git a/packages/durabletask-js/test/activity_executor.spec.ts b/packages/durabletask-js/test/activity_executor.spec.ts
index cbf8236..bafe8ee 100644
--- a/packages/durabletask-js/test/activity_executor.spec.ts
+++ b/packages/durabletask-js/test/activity_executor.spec.ts
@@ -53,12 +53,62 @@ describe("Activity Executor", () => {
     expect(caughtException).not.toBeNull();
     expect(caughtException?.message).toMatch(/Bogus/);
   });
+
+  it("should throw and log activityFailed when input is malformed JSON", async () => {
+    const testActivity = (_: ActivityContext, input: any) => {
+      return input;
+    };
+
+    const loggerSpy = createSpyLogger();
+    const [executor, name] = getActivityExecutor(testActivity, loggerSpy);
+
+    const malformedJson = "{not valid json";
+
+    await expect(executor.execute(TEST_INSTANCE_ID, name, TEST_TASK_ID, malformedJson))
+      .rejects.toThrow(SyntaxError);
+
+    // Verify the activityFailed log (EventId 605) was emitted
+    expect(loggerSpy.error).toHaveBeenCalled();
+    const errorCall = loggerSpy.error.mock.calls[0][0];
+    expect(errorCall).toContain(name);
+    expect(errorCall).toContain(TEST_INSTANCE_ID);
+    expect(errorCall).toContain("failed");
+  });
+
+  it("should handle undefined input without error", async () => {
+    const testActivity = (_: ActivityContext, input: any) => {
+      return input;
+    };
+
+    const [executor, name] = getActivityExecutor(testActivity);
+    const result = await executor.execute(TEST_INSTANCE_ID, name, TEST_TASK_ID, undefined);
+    expect(result).toBeUndefined();
+  });
+
+  it("should handle empty string input without error", async () => {
+    const testActivity = (_: ActivityContext, input: any) => {
+      return input;
+    };
+
+    const [executor, name] = getActivityExecutor(testActivity);
+    const result = await executor.execute(TEST_INSTANCE_ID, name, TEST_TASK_ID, "");
+    expect(result).toBeUndefined();
+  });
 });
 
 // Activity = Callable[[ActivityContext, TInput], TOutput]
-function getActivityExecutor(fn: TActivity<any, any>): [ActivityExecutor, string] {
+function getActivityExecutor(fn: TActivity<any, any>, logger?: any): [ActivityExecutor, string] {
   const registry = new Registry();
   const name = registry.addActivity(fn);
-  const executor = new ActivityExecutor(registry, testLogger);
+  const executor = new ActivityExecutor(registry, logger ?? testLogger);
   return [executor, name];
 }
+
+function createSpyLogger() {
+  return {
+    error: jest.fn(),
+    warn: jest.fn(),
+    info: jest.fn(),
+    debug: jest.fn(),
+  };
+}