feat(typescript): upgrade to TypeScript 5 (#4315)

This upgrades the version of TypeScript bundled with Stencil to 5.0.4. In order to support the upgrade we have to do a few things:

- edit the Rollup plugin we use to bundle typescript to account for changes in how typescript is bundled now (this changed for the 5.0.0 release)
- fix tests which assert on e.g. transformer output to account for small, mostly one-character differences in output with the strings we have in tests
- move the location where we prevent `.d.ts` files being written to disk during `stencil build` for test files
See also a documentation PR here: stenciljs/site#1117

It was also necessary to make a few tweaks to how the Karma tests are run to account for some changes in how TypeScript resolves modules.

Author: alicewriteswrongs

jest.config.js

@@ -11,6 +11,7 @@ module.exports = {
     '@stencil/core/mock-doc': '<rootDir>/mock-doc/index.cjs',
     '@stencil/core/testing': '<rootDir>/testing/index.js',
     '@utils': '<rootDir>/src/utils',
+    '^typescript$': '<rootDir>/scripts/build/typescript-modified-for-jest.js',
   },
   coverageDirectory: './coverage/',
   coverageReporters: ['json', 'lcov', 'text', 'clover'],

package-lock.json

@@ -122,7 +122,7 @@
     "semver": "^7.3.7",
     "sizzle": "^2.3.6",
     "terser": "5.17.4",
-    "typescript": "4.9.5",
+    "typescript": "~5.0.4",
     "webpack": "^5.75.0",
     "ws": "8.13.0"
   },

package.json

@@ -62,57 +62,107 @@ async function bundleTypeScriptSource(tsPath: string, opts: BuildOptions): Promi
 
   // remove the default ts.getDefaultLibFilePath because it uses some
   // node apis and we'll be replacing it with our own anyways
-  code = removeFromSource(code, `ts.getDefaultLibFilePath = getDefaultLibFilePath;`);
+  // TODO(STENCIL-816): remove in-browser compilation
+  code = removeFromSource(code, `getDefaultLibFilePath: () => getDefaultLibFilePath,`);
 
   // remove the CPUProfiler since it uses node apis
-  code = removeFromSource(code, `enableCPUProfiler: enableCPUProfiler,`);
-  code = removeFromSource(code, `disableCPUProfiler: disableCPUProfiler,`);
+  // TODO(STENCIL-816): remove in-browser compilation
+  code = removeFromSource(code, `enableCPUProfiler,`);
+  // TODO(STENCIL-816): remove in-browser compilation
+  code = removeFromSource(code, `disableCPUProfiler,`);
+
+  // As of 5.0, because typescript is now bundled with esbuild the structure of
+  // the file we're dealing with here (`lib/typescript.js`) has changed.
+  // Previously there was an iife which got an object as an argument and just
+  // stuck properties onto it, something like
+  //
+  // ```js
+  // var ts = (function (ts) {
+  //   ts.someMethod = () => { ... };
+  // })(ts || ts = {});
+  // ```
+  //
+  // as of 5.0 it instead looks (conceptually) something like:
+  //
+  // ```js
+  // var ts = (function () {
+  //   const ts = {}
+  //   const define = (name, value) => {
+  //     Object.defineProperty(ts, name, value, { enumerable: true })
+  //   }
+  //   define('someMethod', () => { ... })
+  //   return ts;
+  // })();
+  // ```
+  //
+  // Note that the call to `Object.defineProperty` does not set `configurable` to `true`
+  // (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#description)
+  // which means that later calls to do something like
+  //
+  // ```ts
+  // import ts from 'typescript';
+  //
+  // ts.someMethod = function myReplacementForSomeMethod () {
+  //   ...
+  // };
+  // ```
+  //
+  // will fail because without `configurable: true` you can't re-assign
+  // properties.
+  //
+  // All well and good, except for the fact that our patching of typescript to
+  // use for instance the in-memory file system depends on us being able to
+  // monkey-patch typescript in exactly this way. So in order to retain our
+  // current approach to patching TypeScript we need to edit this file in order
+  // to add `configurable: true` to the options passed to
+  // `Object.defineProperty`:
+  const TS_PROP_DEFINER = `__defProp(target, name, { get: all[name], enumerable: true });`;
+  const TS_PROP_DEFINER_RECONFIGURABLE = `__defProp(target, name, { get: all[name], enumerable: true, configurable: true });`;
+
+  code = code.replace(TS_PROP_DEFINER, TS_PROP_DEFINER_RECONFIGURABLE);
+
+  const jestTypesciptFilename = join(opts.scriptsBuildDir, 'typescript-modified-for-jest.js');
+  await fs.writeFile(jestTypesciptFilename, code);
+
+  // Here we transform the TypeScript source from a commonjs to an ES module.
+  // We do this so that we can add an import from the `@environment` module.
 
   // trim off the last part that sets module.exports and polyfills globalThis since
   // we don't want typescript to add itself to module.exports when in a node env
-  const tsEnding = `})(ts || (ts = {}));`;
+  const tsEnding = `if (typeof module !== "undefined" && module.exports) { module.exports = ts; }`;
+
   if (!code.includes(tsEnding)) {
     throw new Error(`"${tsEnding}" not found`);
   }
   const lastEnding = code.lastIndexOf(tsEnding);
-  code = code.slice(0, lastEnding + tsEnding.length);
-
-  // there's a billion unnecessary "var ts;" for namespaces
-  // but we'll be using the top level "const ts" instead
-  code = code.replace(/var ts;/g, '');
+  code = code.slice(0, lastEnding);
 
-  // minification is crazy better if it doesn't use typescript's
-  // namespace closures, like (function(ts) {...})(ts = ts || {});
-  code = code.replace(/ \|\| \(ts \= \{\}\)/g, '');
-
-  // make a nice clean default export
-  // "process.browser" is used by typescript to know if it should use the node sys or not
   const o: string[] = [];
   o.push(`// TypeScript ${opts.typescriptVersion}`);
   o.push(`import { IS_NODE_ENV } from '@environment';`);
   o.push(`process.browser = !IS_NODE_ENV;`);
-  o.push(`const ts = {};`);
   o.push(code);
   o.push(`export default ts;`);
   code = o.join('\n');
 
-  const { minify } = await import('terser');
-
-  if (opts.isProd) {
-    const minified = await minify(code, {
-      ecma: 2018,
-      module: true,
-      compress: {
-        ecma: 2018,
-        passes: 2,
-      },
-      format: {
-        ecma: 2018,
-        comments: false,
-      },
-    });
-    code = minified.code;
-  }
+  // TODO(STENCIL-839): investigate minification issue w/ typescript 5.0
+  // const { minify } = await import('terser');
+
+  // if (opts.isProd) {
+  //   const minified = await minify(code, {
+  //     ecma: 2018,
+  //     // module: true,
+  //     compress: {
+  //       ecma: 2018,
+  //       passes: 2,
+  //     },
+  //     format: {
+  //       ecma: 2018,
+  //       comments: false,
+  //     },
+  //   });
+  //   code = minified.code;
+  // }
 
   await fs.writeFile(cacheFile, code);
 

scripts/bundles/plugins/typescript-source-plugin.ts

@@ -198,7 +198,6 @@ export const patchTypescript = (config: d.Config, inMemoryFs: InMemoryFileSystem
       patchTsSystemWatch(config.sys, ts.sys);
     }
     patchTypeScriptResolveModule(config, inMemoryFs);
-    patchTypeScriptGetParsedCommandLineOfConfigFile();
     (ts as any).__patched = true;
   }
 };
@@ -243,26 +242,3 @@ export const getTypescriptPathFromUrl = (config: d.Config, tsExecutingUrl: strin
   }
   return url;
 };
-
-export const patchTypeScriptGetParsedCommandLineOfConfigFile = () => {
-  const orgGetParsedCommandLineOfConfigFile = ts.getParsedCommandLineOfConfigFile;
-
-  ts.getParsedCommandLineOfConfigFile = (configFileName, optionsToExtend, host, extendedConfigCache) => {
-    const results = orgGetParsedCommandLineOfConfigFile(configFileName, optionsToExtend, host, extendedConfigCache);
-
-    // manually filter out any .spec or .e2e files
-    results.fileNames = results.fileNames.filter((f) => {
-      // filter e2e tests
-      if (f.includes('.e2e.') || f.includes('/e2e.')) {
-        return false;
-      }
-      // filter spec tests
-      if (f.includes('.spec.') || f.includes('/spec.')) {
-        return false;
-      }
-      return true;
-    });
-
-    return results;
-  };
-};