fix: report CLI read/write errors instead of crashing

spec/cli_spec.js

@@ -0,0 +1,40 @@
+"use strict";
+
+import { spawnSync } from "child_process";
+import path from "path";
+import { fileURLToPath } from "url";
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const cliPath = path.join(__dirname, "../src/cli/cli.js");
+const missingPath = path.join(__dirname, "assets/does-not-exist.xml");
+
+function runCli(args, input) {
+  return spawnSync(process.execPath, [cliPath, ...args], { input, encoding: "utf8" });
+}
+
+describe("CLI", function() {
+
+  it("should parse xml from stdin", function() {
+    const result = runCli([], "<a>1</a>");
+
+    expect(result.status).toBe(0);
+    expect(JSON.parse(result.stdout)).toEqual({ a: 1 });
+  });
+
+  it("should report a missing input file instead of crashing", function() {
+    const result = runCli([missingPath]);
+
+    expect(result.status).toBe(1);
+    expect(result.stdout).toContain("Seems an invalid file or stream.");
+    expect(result.stdout).toContain("ENOENT");
+    expect(result.stderr).not.toContain("throw err");
+  });
+
+  it("should report an unwritable output file instead of crashing", function() {
+    const result = runCli(["-o", path.join(missingPath, "out.json")], "<a>1</a>");
+
+    expect(result.status).toBe(1);
+    expect(result.stdout).toContain("Seems an invalid file or stream.");
+    expect(result.stderr).not.toContain("throw err");
+  });
+});

src/cli/cli.js

@@ -70,27 +70,37 @@ if (process.argv[2] === '--help' || process.argv[2] === '-h') {
     if (!fileName) {
       ReadToEnd.readToEnd(process.stdin, function(err, data) {
         if (err) {
-          throw err;
+          onError(err);
+          return;
         }
         callback(data.toString());
       });
     } else {
       fs.readFile(fileName, function(err, data) {
         if (err) {
-          throw err;
+          onError(err);
+          return;
         }
         callback(data.toString());
       });
     }
   } catch (e) {
-    console.log('Seems an invalid file or stream.' + e);
+    onError(e);
   }
 }
 
+// errors raised inside async callbacks are not caught by the try/catch above,
+// so they are reported here instead of being thrown
+function onError(err) {
+  console.log('Seems an invalid file or stream.' + err);
+  process.exitCode = 1;
+}
+
 function writeToFile(fileName, data) {
   fs.writeFile(fileName, data, function(err) {
     if (err) {
-      throw err;
+      onError(err);
+      return;
     }
     console.log('JSON output has been written to ' + fileName);
   });