Fix: get state should not return the number 0 as null

src/state_machine.ts

@@ -174,7 +174,7 @@ export class DurableExecutionStateMachine<I, O> implements RestateContext {
 
     const msg = GetStateEntryMessage.create({ key: Buffer.from(name) });
 
-    const promise = this.storePendingMsg(
+    const promise = this.storePendingMsg<Buffer | Empty>(
       this.currentJournalIndex,
       GET_STATE_ENTRY_MESSAGE_TYPE,
       msg
@@ -193,10 +193,15 @@ export class DurableExecutionStateMachine<I, O> implements RestateContext {
 
     const result = await promise;
 
-    if (result == null || JSON.stringify(result) === "{}") {
-      return null;
+    if (result instanceof Buffer) {
+      const resultString = result.toString();
+      if (resultString === "0") {
+        return resultString as T;
+      }
+
+      return JSON.parse(resultString) as T;
     } else {
-      return JSON.parse(result.toString()) as T;
+      return null;
     }
   }
 

test/get_state.test.ts

@@ -1,3 +1,5 @@
+"use strict";
+
 import { describe, expect } from "@jest/globals";
 import * as restate from "../src/public_api";
 import { TestDriver } from "./testdriver";
@@ -25,12 +27,44 @@ class GetStateGreeter implements TestGreeter {
     const ctx = restate.useContext(this);
 
     // state
-    const state = (await ctx.get<string>("STATE")) || "nobody";
+    let state = await ctx.get<string>("STATE");
+    if (state === null) {
+      state = "nobody";
+    }
+
+    return TestResponse.create({ greeting: `Hello ${state}` });
+  }
+}
+
+class NumberGetStateGreeter implements TestGreeter {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  async greet(request: TestRequest): Promise<TestResponse> {
+    const ctx = restate.useContext(this);
+
+    // state
+    const state = (await ctx.get<number>("STATE")) || 0;
 
     return TestResponse.create({ greeting: `Hello ${state}` });
   }
 }
 
+class NumberListGetStateGreeter implements TestGreeter {
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  async greet(request: TestRequest): Promise<TestResponse> {
+    const ctx = restate.useContext(this);
+
+    // state
+    const state = await ctx.get<number[]>("STATE");
+    if (state) {
+      return TestResponse.create({
+        greeting: `Hello index 0: ${state[0]} - index 1: ${state[1]}`,
+      });
+    } else {
+      return TestResponse.create({ greeting: `Hello no state found` });
+    }
+  }
+}
+
 describe("GetStateGreeter: With GetStateEntry already complete", () => {
   it("should call greet", async () => {
     const result = await new TestDriver(
@@ -127,3 +161,112 @@ describe("GetStateGreeter: Without GetStateEntry and completed with later Comple
     ]);
   });
 });
+
+describe("GetStateGreeter: Without GetStateEntry and completed with later CompletionFrame with empty string", () => {
+  it("should call greet", async () => {
+    const result = await new TestDriver(
+      protoMetadata,
+      "TestGreeter",
+      new GetStateGreeter(),
+      "/test.TestGreeter/Greet",
+      [
+        startMessage(1),
+        inputMessage(greetRequest("Till")),
+        completionMessage(1, Buffer.from(JSON.stringify(""))),
+      ]
+    ).run();
+
+    expect(result).toStrictEqual([
+      getStateMessage("STATE"),
+      outputMessage(greetResponse("Hello ")),
+    ]);
+  });
+});
+
+describe("NumberGetStateGreeter: Without GetStateEntry and completed with later CompletionFrame with numeric value 70", () => {
+  it("should call greet", async () => {
+    const result = await new TestDriver(
+      protoMetadata,
+      "TestGreeter",
+      new NumberGetStateGreeter(),
+      "/test.TestGreeter/Greet",
+      [
+        startMessage(1),
+        inputMessage(greetRequest("Till")),
+        completionMessage(1, Buffer.from(JSON.stringify(70))),
+      ]
+    ).run();
+
+    expect(result).toStrictEqual([
+      getStateMessage("STATE"),
+      outputMessage(greetResponse("Hello 70")),
+    ]);
+  });
+});
+
+describe("NumberGetStateGreeter: Without GetStateEntry and completed with later CompletionFrame with value 0", () => {
+  it("should call greet", async () => {
+    const result = await new TestDriver(
+      protoMetadata,
+      "TestGreeter",
+      new NumberGetStateGreeter(),
+      "/test.TestGreeter/Greet",
+      [
+        startMessage(1),
+        inputMessage(greetRequest("Till")),
+        completionMessage(1, Buffer.from(JSON.stringify(0))),
+      ]
+    ).run();
+
+    expect(result).toStrictEqual([
+      getStateMessage("STATE"),
+      outputMessage(greetResponse("Hello 0")),
+    ]);
+  });
+});
+
+describe("NumberListGetStateGreeter: Without GetStateEntry and completed with later CompletionFrame with list state", () => {
+  it("should call greet", async () => {
+    const result = await new TestDriver(
+      protoMetadata,
+      "TestGreeter",
+      new NumberListGetStateGreeter(),
+      "/test.TestGreeter/Greet",
+      [
+        startMessage(1),
+        inputMessage(greetRequest("Till")),
+        completionMessage(1, Buffer.from(JSON.stringify([5, 4]))),
+      ]
+    ).run();
+
+    expect(result).toStrictEqual([
+      getStateMessage("STATE"),
+      outputMessage(greetResponse("Hello index 0: 5 - index 1: 4")),
+    ]);
+  });
+});
+
+describe("NumberListGetStateGreeter: Without GetStateEntry and completed with later CompletionFrame with empty list state", () => {
+  it("should call greet", async () => {
+    const result = await new TestDriver(
+      protoMetadata,
+      "TestGreeter",
+      new NumberListGetStateGreeter(),
+      "/test.TestGreeter/Greet",
+      [
+        startMessage(1),
+        inputMessage(greetRequest("Till")),
+        completionMessage(1, Buffer.from(JSON.stringify([]))),
+      ]
+    ).run();
+
+    // For an empty list it will print undefined values for the first two indices
+    // but still recognize it as a list
+    expect(result).toStrictEqual([
+      getStateMessage("STATE"),
+      outputMessage(
+        greetResponse("Hello index 0: undefined - index 1: undefined")
+      ),
+    ]);
+  });
+});