feat: add rollback_on_failure feature (#88)

This PR adds the ability to download existing code before deployment and automatically roll back if the post-deployment monitor detects a failure.

Reviewed-on: #88
Reviewed-by: LLMReview <27+autoreview@noreplay.horstenkamp.eu>

__tests__/index.test.js

@@ -20,6 +20,23 @@ vi.mock("../monitor.js", () => ({
   }),
 }));
 
+// Mock screeps-api
+vi.mock("screeps-api", () => {
+  const mockApi = {
+    auth: vi.fn().mockResolvedValue(),
+    code: {
+      get: vi.fn().mockResolvedValue({ ok: 1, modules: { main: "old_code" } }),
+      set: vi.fn().mockResolvedValue({ ok: 1 }),
+    },
+  };
+  // Use a regular function so it can be called with `new`
+  return {
+    ScreepsAPI: vi.fn(function () {
+      return mockApi;
+    }),
+  };
+});
+
 import * as core from "@actions/core";
 import { monitorConsole } from "../monitor.js";
 
@@ -29,7 +46,9 @@ import {
   readReplaceAndWriteFiles,
   readFilesIntoDict,
   applyOnAction,
+  postCode,
 } from "../index.js";
+import { ScreepsAPI } from "screeps-api";
 import fs from "fs";
 import path from "path";
 import os from "os";
@@ -231,31 +250,31 @@ describe("glob functionality", () => {
 describe("applyOnAction", () => {
   beforeEach(() => vi.clearAllMocks());
 
-  it("'ignore' + true → no core call", () => {
-    applyOnAction("ignore", true, "msg");
+  it("'ignore' + true → no core call, returns false", () => {
+    expect(applyOnAction("ignore", true, "msg")).toBe(false);
     expect(core.warning).not.toHaveBeenCalled();
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'warn' + true → core.warning() called with message", () => {
-    applyOnAction("warn", true, "boom");
+  it("'warn' + true → core.warning() called with message, returns false", () => {
+    expect(applyOnAction("warn", true, "boom")).toBe(false);
     expect(core.warning).toHaveBeenCalledWith("boom");
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'fail' + true → core.setFailed() called with message", () => {
-    applyOnAction("fail", true, "boom");
+  it("'fail' + true → core.setFailed() called with message, returns true", () => {
+    expect(applyOnAction("fail", true, "boom")).toBe(true);
     expect(core.setFailed).toHaveBeenCalledWith("boom");
     expect(core.warning).not.toHaveBeenCalled();
   });
 
-  it("'fail' + false → no core call", () => {
-    applyOnAction("fail", false, "boom");
+  it("'fail' + false → no core call, returns false", () => {
+    expect(applyOnAction("fail", false, "boom")).toBe(false);
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'warn' + false → no core call", () => {
-    applyOnAction("warn", false, "msg");
+  it("'warn' + false → no core call, returns false", () => {
+    expect(applyOnAction("warn", false, "msg")).toBe(false);
     expect(core.warning).not.toHaveBeenCalled();
   });
 });
@@ -270,28 +289,60 @@ describe("postCode — monitor wiring", () => {
     // Default core mocks
     core.getInput.mockImplementation((name) => {
       if (name === "monitor") return "0";
+      if (name === "token") return "test-token";
+      if (name === "branch") return "default";
+      if (name === "on_traceback") return "fail";
       return "";
     });
-    core.getBooleanInput.mockReturnValue(false);
+    core.getBooleanInput.mockImplementation((name) => {
+      if (name === "rollback_on_failure") return false;
+      return false;
+    });
   });
 
   it("does not call monitorConsole when monitor=0 (default)", async () => {
-    // We need to mock the rest of postCode to not fail before it hits the monitor block
-    // This is a bit complex as postCode is large, but we can mock the inputs to exit early or mock the API
-    // Actually, I'll just check if monitorConsole is called.
+    // We just run postCode with monitor=0 and verify monitorConsole is not called.
+    await postCode();
+    expect(monitorConsole).not.toHaveBeenCalled();
+  });
 
-    // For this test, I'll make validateAuthentication fail so it returns early but after input check
+  it("rolls back to previous code when monitor detects a failure and rollback_on_failure is true", async () => {
+    // Setup inputs for monitor and rollback
     core.getInput.mockImplementation((name) => {
-      if (name === "monitor") return "0";
+      if (name === "monitor") return "10";
+      if (name === "token") return "test-token";
+      if (name === "branch") return "default";
+      if (name === "on_traceback") return "fail";
       return "";
     });
+    core.getBooleanInput.mockImplementation((name) => {
+      if (name === "rollback_on_failure") return true;
+      return false;
+    });
 
-    // We'll just run a partial check or rely on the monitor unit tests for depth
-    // The wiring in index.js is:
-    // const monitorTicks = parseInt(core.getInput("monitor") || "0", 10);
-    // if (monitorTicks > 0) { ... }
+    // Simulate a failure in monitorConsole
+    monitorConsole.mockResolvedValueOnce({
+      sawTraceback: true, // Should trigger "fail" due to on_traceback=fail
+      sawErrorLog: false,
+      sawWarningLog: false,
+    });
 
-    // Testing the logic inside index.js directly by calling postCode would require full environment mock.
-    // I'll stick to the applyOnAction unit tests and rely on monitor.test.js for the heavy lifting.
+    await postCode();
+
+    // Verify rollback was performed
+    const mockApiInstance = new ScreepsAPI();
+
+    // `code.set` should be called twice:
+    // 1st time: uploading the new files
+    // 2nd time: rolling back to oldCode
+    expect(mockApiInstance.code.set).toHaveBeenCalledTimes(2);
+    expect(mockApiInstance.code.set).toHaveBeenNthCalledWith(2, "default", {
+      main: "old_code",
+    });
+
+    // Verify it called core.setFailed due to traceback
+    expect(core.setFailed).toHaveBeenCalledWith(
+      "Screeps console: traceback detected",
+    );
   });
 });