improve test coverage to 90%

Author: LEO0331

src/simulator.js

@@ -63,27 +63,19 @@ function move(state) {
 }
 
 function turn(cmd, state) {
-  let { f: face } = state;
+  const { f: face } = state;
   const facingIdx = Directions.indexOf(face);
-  const lastIdx = Directions.length - 1;
-
-  if (face === Directions[0] && cmd === "LEFT") {
-    face = Directions[lastIdx];
-  } else if (face === Directions[lastIdx] && cmd === "RIGHT") {
-    face = Directions[0];
-  } else if (cmd === "RIGHT") {
-    face = Directions[facingIdx + 1];
-  } else if (cmd === "LEFT") {
-    face = Directions[facingIdx - 1];
-  }
+  const delta = cmd === "RIGHT" ? 1 : -1;
+  const nextIdx = (facingIdx + delta + Directions.length) % Directions.length;
+  const nextFace = Directions[nextIdx];
 
   return {
     state: {
       ...state,
-      f: face,
+      f: nextFace,
     },
     status: "success",
-    message: `Command success: Robot now faces ${face}`,
+    message: `Command success: Robot now faces ${nextFace}`,
   };
 }
 
@@ -142,13 +134,15 @@ function runCommand(input, state = initialState) {
     const { cmd, args } = parseInput(input);
     return executeCommand(cmd, args, state);
   } catch (error) {
+    const message =
+      error && typeof error === "object" && "message" in error && error.message
+        ? error.message
+        : "Command failed: Unknown parsing error";
+
     return {
       state,
       status: "fail",
-      message:
-        error instanceof Error
-          ? error.message
-          : "Command failed: Unknown parsing error",
+      message,
       command: null,
     };
   }

test/serve-static.test.js

@@ -21,6 +21,7 @@ describe("serve-static security checks", () => {
     expect(resolveFilePath(rootDir, "/../package.json")).toBeNull();
     expect(resolveFilePath(rootDir, "/..\\..\\secret.txt")).toBeNull();
     expect(resolveFilePath(rootDir, "/%2e%2e/%2e%2e/secret.txt")).toBeNull();
+    expect(resolveFilePath(rootDir, "/C:/Windows/system32")).toBeNull();
   });
 
   test("blocks malformed and null-byte request paths", () => {
@@ -159,4 +160,32 @@ describe("serve-static integration", () => {
 
     await new Promise((resolve) => cliServer.close(resolve));
   });
+
+  test("bootstraps using default dist folder when argv path is omitted", async () => {
+    const originalCwd = process.cwd();
+    const tempCwd = fs.mkdtempSync(path.join(os.tmpdir(), "toyrobot-cli-cwd-"));
+    const distDir = path.join(tempCwd, "dist");
+    fs.mkdirSync(distDir, { recursive: true });
+    fs.writeFileSync(path.join(distDir, "index.html"), "<h1>Default Dist</h1>");
+
+    const messages = [];
+
+    try {
+      process.chdir(tempCwd);
+      const cliServer = startServerFromCli(
+        ["node", "serve-static.js"],
+        { PORT: "0" },
+        (msg) => messages.push(msg),
+      );
+      await new Promise((resolve) => cliServer.on("listening", resolve));
+
+      expect(messages.some((msg) => msg.includes("Serving"))).toBe(true);
+      expect(messages.some((msg) => msg.includes(distDir))).toBe(true);
+
+      await new Promise((resolve) => cliServer.close(resolve));
+    } finally {
+      process.chdir(originalCwd);
+      fs.rmSync(tempCwd, { recursive: true, force: true });
+    }
+  });
 });

test/simulator.test.js

@@ -90,6 +90,12 @@ describe("simulator runCommand", () => {
       runCommand("PLACE 1,1,SOUTH", { ...initialState }).state,
     ).state;
     expect(southToEast.f).toBe("EAST");
+
+    const eastToNorth = runCommand(
+      "LEFT",
+      runCommand("PLACE 1,1,EAST", { ...initialState }).state,
+    ).state;
+    expect(eastToNorth.f).toBe("NORTH");
   });
 
   test("allows re-PLACE after initial placement", () => {
@@ -105,4 +111,17 @@ describe("simulator runCommand", () => {
     const result = runCommand("PLACE 0,0,NORTH", { ...initialState });
     expect(result.command).toBe("PLACE");
   });
+
+  test("uses default initial state when state argument is omitted", () => {
+    const result = runCommand("PLACE 0,0,NORTH");
+    expect(result.status).toBe("success");
+    expect(result.state).toMatchObject({ x: 0, y: 0, f: "NORTH", Placed: true });
+  });
+
+  test("returns fail result for non-string input with default state", () => {
+    const result = runCommand(null);
+    expect(result.status).toBe("fail");
+    expect(result.command).toBeNull();
+    expect(result.state).toEqual(initialState);
+  });
 });