From c2fe3f152059b5c0323190e57ffed8f762efd4b7 Mon Sep 17 00:00:00 2001
From: Harminder Virk <virk.officials@gmail.com>
Date: Tue, 22 Apr 2025 16:27:15 +0530
Subject: [PATCH] fix: steps to return undefined and still chain the config
 method (#12255)

Fixes: FRMW-2946
---
 .changeset/popular-windows-agree.md           |  5 +++
 .../workflows-sdk/src/utils/_playground.ts    | 14 ++++++
 .../src/utils/composer/__tests__/compose.ts   | 44 +++++--------------
 .../workflows-sdk/src/utils/composer/type.ts  |  6 ++-
 4 files changed, 36 insertions(+), 33 deletions(-)
 create mode 100644 .changeset/popular-windows-agree.md

diff --git a/.changeset/popular-windows-agree.md b/.changeset/popular-windows-agree.md
new file mode 100644
index 0000000000..d3657ba0d4
--- /dev/null
+++ b/.changeset/popular-windows-agree.md
@@ -0,0 +1,5 @@
+---
+"@medusajs/workflows-sdk": patch
+---
+
+fix: steps to return undefined and still chain the config method
diff --git a/packages/core/workflows-sdk/src/utils/_playground.ts b/packages/core/workflows-sdk/src/utils/_playground.ts
index fdca4027ce..70ee2ecca9 100644
--- a/packages/core/workflows-sdk/src/utils/_playground.ts
+++ b/packages/core/workflows-sdk/src/utils/_playground.ts
@@ -21,6 +21,14 @@ const step3 = createStep("step3", async function (_, context) {
   return new StepResponse({ step3: "step3" })
 })
 
+const step4 = createStep("step4", async function (_, context) {
+  return new StepResponse<undefined | { id: number }>({ id: 1 })
+})
+
+const step5 = createStep("step5", async function (_, context) {
+  return new StepResponse(void 0)
+})
+
 const workflow = createWorkflow(
   "sub-workflow",
   function (input: WorkflowData<{ outsideWorkflowData: string }>) {
@@ -37,6 +45,12 @@ const workflow = createWorkflow(
       }
     )
 
+    const step4Result = step4().config({ name: "foo" })
+    step4Result
+
+    const step5Result = step5().config({ name: "foo" })
+    step5Result
+
     return new WorkflowResponse(
       { r: somethingHook.getResult(), step3: step3() },
       { hooks: [somethingHook] }
diff --git a/packages/core/workflows-sdk/src/utils/composer/__tests__/compose.ts b/packages/core/workflows-sdk/src/utils/composer/__tests__/compose.ts
index 276071f2d4..21a5f3ce75 100644
--- a/packages/core/workflows-sdk/src/utils/composer/__tests__/compose.ts
+++ b/packages/core/workflows-sdk/src/utils/composer/__tests__/compose.ts
@@ -852,7 +852,7 @@ describe("Workflow composer", function () {
       )
       const step4 = createStep(
         "step4",
-        mockStep4Fn as unknown as StepFunction<never, never>,
+        mockStep4Fn as unknown as StepFunction<never, StepResponse<void>>,
         step4CompensationFn
       )
 
@@ -923,7 +923,7 @@ describe("Workflow composer", function () {
       )
       const step4 = createStep(
         "step4",
-        mockStep4Fn as unknown as StepFunction<never, never>,
+        mockStep4Fn as unknown as StepFunction<never, StepResponse<void>>,
         step4CompensationFn
       )
 
@@ -2002,14 +2002,10 @@ describe("Workflow composer", function () {
         mockStep3Fn as unknown as StepFunction<never, StepResponse<string>>,
         step3CompensationFn
       )
-      const step4 = createStep(
-        "step4",
-        mockStep4Fn as unknown as StepFunction<never, never>,
-        step4CompensationFn
-      )
+      const step4 = createStep("step4", mockStep4Fn, step4CompensationFn)
 
       const workflow = createWorkflow("workflow1", function (input) {
-        const [step1Res] = parallelize(step1(), step2(), step3(), step4())
+        const [step1Res] = parallelize(step1(), step2(), step3(), step4({}))
         return new WorkflowResponse(step1Res)
       })
 
@@ -2058,33 +2054,17 @@ describe("Workflow composer", function () {
         throw new Error("An error occured in step 4.")
       })
 
-      const step1 = createStep(
-        "step1",
-        mockStep1Fn as unknown as StepFunction<never, StepResponse<string>>,
-        step1CompensationFn
-      )
-      const step2 = createStep(
-        "step2",
-        mockStep2Fn as unknown as StepFunction<never, StepResponse<string>>,
-        step2CompensationFn
-      )
-      const step3 = createStep(
-        "step3",
-        mockStep3Fn as unknown as StepFunction<never, StepResponse<string>>,
-        step3CompensationFn
-      )
-      const step4 = createStep(
-        "step4",
-        mockStep4Fn as unknown as StepFunction<never, never>,
-        step4CompensationFn
-      )
+      const step1 = createStep("step1", mockStep1Fn, step1CompensationFn)
+      const step2 = createStep("step2", mockStep2Fn, step2CompensationFn)
+      const step3 = createStep("step3", mockStep3Fn, step3CompensationFn)
+      const step4 = createStep("step4", mockStep4Fn, step4CompensationFn)
 
       const workflow = createWorkflow("workflow1", function (input) {
         const [step1Res] = parallelize(
-          step1().config({ name: "newStep1Name" }),
-          step2(),
-          step3(),
-          step4()
+          step1({}).config({ name: "newStep1Name" }),
+          step2({}),
+          step3({}),
+          step4({})
         )
         return new WorkflowResponse(step1Res)
       })
diff --git a/packages/core/workflows-sdk/src/utils/composer/type.ts b/packages/core/workflows-sdk/src/utils/composer/type.ts
index 9c7ef06b1e..843418ac74 100644
--- a/packages/core/workflows-sdk/src/utils/composer/type.ts
+++ b/packages/core/workflows-sdk/src/utils/composer/type.ts
@@ -50,6 +50,8 @@ type ConvertHooksToFunctions<THooks extends any[]> = THooks extends [
   ? ConvertHookToObject<A> & ConvertHooksToFunctions<R>
   : {}
 
+export type Void = { " $$type": "void" }
+
 /**
  * A step function to be used in a workflow.
  *
@@ -62,7 +64,9 @@ export type StepFunction<
 > = (KeysOfUnion<TInput> extends []
   ? // Function that doesn't expect any input
     {
-      (): WorkflowData<TOutput> & StepFunctionReturnConfig<TOutput>
+      (): TOutput & {} extends never
+        ? WorkflowData<Void> & StepFunctionReturnConfig<TOutput>
+        : WorkflowData<TOutput> & StepFunctionReturnConfig<TOutput>
     }
   : // function that expects an input object
     {