test: test snapshotting TypeScript compiler

PR-URL: https://github.com/nodejs/node/pull/38905
Refs: https://github.com/nodejs/node/issues/35711
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

test/fixtures/snapshot/ts-example.js

@@ -0,0 +1,8 @@
+var VirtualPoint = /** @class */ (function () {
+    function VirtualPoint(x, y) {
+        this.x = x;
+        this.y = y;
+    }
+    return VirtualPoint;
+}());
+var newVPoint = new VirtualPoint(13, 56);

test/fixtures/snapshot/ts-example.ts

@@ -0,0 +1,11 @@
+class VirtualPoint {
+  x: number;
+  y: number;
+ 
+  constructor(x: number, y: number) {
+    this.x = x;
+    this.y = y;
+  }
+}
+ 
+const newVPoint = new VirtualPoint(13, 56);

test/fixtures/snapshot/typescript-main.js

@@ -0,0 +1,28 @@
+// This file is to be concatenated with
+// https://github.com/microsoft/TypeScript/blob/main/lib/typescript.js
+// to produce a snapshot that reads a file path from the command
+// line and compile it into JavaScript, then write the
+// result into another file.
+
+const fs = require('fs');
+const v8 = require('v8');
+const assert = require('assert');
+
+v8.startupSnapshot.setDeserializeMainFunction(( { ts }) => {
+  const input = process.argv[1];
+  const output = process.argv[2];
+  console.error(`Compiling ${input} to ${output}`);
+  assert(input);
+  assert(output);
+  const source = fs.readFileSync(input, 'utf8');
+
+  let result = ts.transpileModule(
+    source,
+    {
+      compilerOptions: {
+        module: ts.ModuleKind.CommonJS
+      }
+    });
+
+  fs.writeFileSync(output, result.outputText, 'utf8');
+}, { ts });

test/parallel/test-snapshot-typescript.js

@@ -0,0 +1,69 @@
+'use strict';
+
+// This tests the TypeScript compiler in the snapshot.
+
+const common = require('../common');
+
+if (process.features.debug) {
+  common.skip('V8 snapshot does not work with mutated globals yet: ' +
+              'https://bugs.chromium.org/p/v8/issues/detail?id=12772');
+}
+
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+const tmpdir = require('../common/tmpdir');
+const fixtures = require('../common/fixtures');
+const path = require('path');
+const fs = require('fs');
+
+tmpdir.refresh();
+const blobPath = path.join(tmpdir.path, 'snapshot.blob');
+
+// Concat test/fixtures/snapshot/typescript.js with
+// test/fixtures/snapshot/typescript.js into
+// tmpdir/snapshot.js.
+const file = path.join(tmpdir.path, 'snapshot.js');
+fs.copyFileSync(fixtures.path('snapshot', 'typescript.js'), file);
+fs.appendFileSync(file,
+                  fs.readFileSync(fixtures.path('snapshot', 'typescript-main.js')));
+
+{
+  const child = spawnSync(process.execPath, [
+    '--snapshot-blob',
+    blobPath,
+    '--build-snapshot',
+    file,
+  ], {
+    cwd: tmpdir.path
+  });
+  const stderr = child.stderr.toString();
+  const stdout = child.stdout.toString();
+  console.log(stderr);
+  console.log(stdout);
+  assert.strictEqual(child.status, 0);
+
+  const stats = fs.statSync(path.join(tmpdir.path, 'snapshot.blob'));
+  assert(stats.isFile());
+}
+
+{
+  const outPath = path.join(tmpdir.path, 'ts-example.js');
+  const child = spawnSync(process.execPath, [
+    '--snapshot-blob',
+    blobPath,
+    fixtures.path('snapshot', 'ts-example.ts'),
+    outPath,
+  ], {
+    cwd: tmpdir.path,
+  });
+  const stderr = child.stderr.toString();
+  const snapshotOutput = child.stdout.toString();
+  console.log(stderr);
+  console.log(snapshotOutput);
+
+  assert.strictEqual(child.status, 0);
+  const result = fs.readFileSync(outPath, 'utf8');
+  const expected = fs.readFileSync(
+    fixtures.path('snapshot', 'ts-example.js'), 'utf8');
+  assert.strictEqual(result, expected);
+}