Replace ts-node with the TypeScript language service

CHANGELOG

@@ -1,86 +1,134 @@
 # Changelog
+
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+## [3.0.0-beta.1]
+
+### Changed
+
+- Remove dependency on `ts-node` to avoid memory issues when compiling many snippets.
+  - [BREAKING] Compilation errors are now `CompilationError` instances, not `TSNode.TSError` instances
+- Compile snippets in series to avoid memory issues.
+
+### Removed
+
+- [BREAKING] Support for TypeScript versions <4.7.2
+- [BREAKING] Support for Node.js <20
+- Production dependency on `tsconfig` and `strip-ansi` and `fs-extra`
+
 ## [2.5.3]
+
 ### Changed
+
 - Use a separate `ts-node` compiler per-snippet to ensure that compilation of snippets is independent
 
 ## [2.5.2]
+
 ### Removed
+
 - Obsolete Travis CI build badge from README
 
 ## [2.5.1]
+
 ### Added
+
 - Override any project-specific `ts-node` `transpileOnly` to force type checking when compiling code snippets
 
 ## [2.5.0]
+
 ### Added
+
 - Support for `tsx` snippets
 
 ## [2.4.1]
+
 ### Changed
+
 - Various fixes for Windows environments
 
 ## [2.4.0]
+
 ### Added
+
 - A new `--project` option that overrides the `tsconfig.json` file to be used when compiling snippets
 
 ## [2.3.1]
+
 ### Changed
+
 - Update dependencies
 
 ## [2.3.0]
+
 ### Added
+
 - Support for `exports` in `package.json` including wildcard subpaths
 
 ### Changed
+
 - Compile documentation snippets in the project folder so that dependent packages can be resolved reliably even in nested projects
 
 ## [2.2.2]
+
 ### Changed
+
 - Unpinned `ts-node` dependency to fix issues with the most recent TypeScript versions (required the extraction of the line numbers of compilation errors to be changed)
 
 ## [2.2.1]
+
 ### Added
+
 - Allow code blocks to be ignored by preceding them with a `<!-- ts-docs-verifier:ignore -->` comment
 
 ## [2.2.0]
+
 ### Changed
+
 - Link project `node_modules` to snippet compilation directory so you can import from the current project's dependencies in snippets
 
 ### Added
+
 - Support for importing sub-paths within packages
 - Support for scoped package names
 
 ## [2.1.0]
+
 ### Changed
+
 - No longer wrap TypeScript code blocks in functions before compilation
 - Write temporary files to the OS temporary directory
 
 ### Added
+
 - An 1-indexed `index` property to the `CodeBlock` type to indicate where in the file the code block was found
 - Add a `linesWithErrors` property to the compilation result to indicate which lines contained errors
 
 ## [2.0.1] - 2021-10-08
+
 ### Changed
+
 - Updated dependencies (including dropping `tslint` in favour of `eslint`)
   - Pin to version 5.x.x of `ora` to avoid issues with ESM
 
 ## [2.0.0-rc.1] - 2021-09-27
+
 ### Added
+
 - Support for TypeScript code blocked marked with \`\`\`ts as well as ```typescript
 - This changelog 🎉
 
 ### Changed
+
 - [BREAKING] TypeScript is now a peerDependency and must be installed by the client.
 - Tagging of the source is now done using a `release` branch.
 - Migrated code to `async` / `await`.
 
 ### Removed
+
 - [BREAKING] Support for NodeJS versions prior to version 12.
 - Bluebird dependency.

index.ts

@@ -1,11 +1,10 @@
-import * as path from "path";
 import { PackageInfo } from "./src/PackageInfo";
 import {
   SnippetCompiler,
   SnippetCompilationResult,
 } from "./src/SnippetCompiler";
 
-export { SnippetCompilationResult } from "./src/SnippetCompiler";
+export type { SnippetCompilationResult, CompilationError } from "./src/SnippetCompiler";
 
 const DEFAULT_FILES = ["README.md"];
 
@@ -40,12 +39,8 @@ export async function compileSnippets(
   const { project, markdownFiles } = parseArguments(args);
 
   const packageDefinition = await PackageInfo.read();
-  const compiledDocsFolder = path.join(
-    packageDefinition.packageRoot,
-    ".tmp-compiled-docs"
-  );
   const compiler = new SnippetCompiler(
-    compiledDocsFolder,
+    packageDefinition.packageRoot,
     packageDefinition,
     project
   );

package.json

@@ -18,7 +18,7 @@
     "typescript",
     "verify"
   ],
-  "version": "2.5.3",
+  "version": "3.0.0-beta.1",
   "main": "dist/index.js",
   "@types": "dist/index.d.ts",
   "bin": {
@@ -35,7 +35,7 @@
   },
   "homepage": "https://github.com/bbc/typescript-docs-verifier#readme",
   "engines": {
-    "node": ">=12"
+    "node": ">=20"
   },
   "scripts": {
     "format": "prettier --write '**/*.ts' '**/*.json'",
@@ -54,7 +54,7 @@
     "@types/chai-as-promised": "^8.0.1",
     "@types/fs-extra": "^11.0.4",
     "@types/mocha": "^10.0.10",
-    "@types/node": "^16.11.59",
+    "@types/node": "^20.19.1",
     "@types/react": "^18.2.12",
     "@types/yargs": "^17.0.12",
     "@typescript-eslint/eslint-plugin": "^8.24.0",
@@ -66,25 +66,23 @@
     "eslint-plugin-functional": "^6.6.3",
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-promise": "^7.2.1",
+    "fs-extra": "^11.3.0",
     "mocha": "^11.1.0",
     "npm-run-all2": "^7.0.2",
     "nyc": "^17.1.0",
     "prettier": "^3.5.1",
     "react": "^18.2.0",
-    "typescript": "^4.7.3",
+    "ts-node": "^10.9.2",
+    "typescript": "^4.7.2",
     "verify-it": "^2.3.3"
   },
   "dependencies": {
     "chalk": "^4.1.2",
-    "fs-extra": "^10.0.0",
     "ora": "^5.4.1",
-    "strip-ansi": "^7.0.1",
-    "ts-node": "^10.8.1",
-    "tsconfig": "^7.0.0",
     "yargs": "^17.5.1"
   },
   "peerDependencies": {
-    "typescript": ">3.8.3"
+    "typescript": ">=4.7.2"
   },
   "files": [
     "dist/index.js",

src/CodeBlockExtractor.ts

@@ -1,4 +1,4 @@
-import * as fsExtra from "fs-extra";
+import { readFile } from "fs/promises";
 
 // eslint-disable-next-line @typescript-eslint/no-extraneous-class
 export class CodeBlockExtractor {
@@ -26,7 +26,7 @@ export class CodeBlockExtractor {
   }
 
   private static async readFile(path: string): Promise<string> {
-    return await fsExtra.readFile(path, "utf-8");
+    return await readFile(path, "utf-8");
   }
 
   private static extractCodeBlocksFromMarkdown(

src/CodeCompiler.ts

@@ -0,0 +1,98 @@
+import ts from "typescript";
+
+const createServiceHost = (
+  options: ts.CompilerOptions,
+  workingDirectory: string,
+  fileMap: Map<string, string>
+): ts.LanguageServiceHost => ({
+  getScriptFileNames: () => {
+    return [...fileMap.keys()];
+  },
+  getScriptVersion: () => "1",
+  getProjectVersion: () => "1",
+  getScriptSnapshot: (fileName) => {
+    const contents =
+      fileMap.get(fileName) ?? ts.sys.readFile(fileName, "utf-8");
+
+    return typeof contents === "undefined"
+      ? contents
+      : ts.ScriptSnapshot.fromString(contents);
+  },
+  readFile: (fileName) => {
+    return fileMap.get(fileName) ?? ts.sys.readFile(fileName);
+  },
+  fileExists: (fileName) => {
+    return fileMap.has(fileName) || ts.sys.fileExists(fileName);
+  },
+  getCurrentDirectory: () => workingDirectory,
+  getDirectories: ts.sys.getDirectories,
+  directoryExists: ts.sys.directoryExists,
+  getCompilationSettings: () => options,
+  getDefaultLibFileName: () => ts.getDefaultLibFilePath(options),
+});
+
+export const compile = async ({
+  compilerOptions,
+  workingDirectory,
+  code,
+  type,
+}: {
+  compilerOptions: ts.CompilerOptions;
+  workingDirectory: string;
+  code: string;
+  type: "ts" | "tsx";
+}): Promise<{
+  hasError: boolean;
+  diagnostics: ReadonlyArray<ts.Diagnostic>;
+}> => {
+  const id = process.hrtime.bigint().toString();
+  const filename = `block-${id}.${type}`;
+
+  const fileMap = new Map<string, string>([[filename, code]]);
+
+  const registry = ts.createDocumentRegistry(
+    ts.sys.useCaseSensitiveFileNames,
+    workingDirectory
+  );
+
+  const serviceHost = createServiceHost(
+    {
+      ...compilerOptions,
+      noEmit: false,
+      declaration: false,
+      sourceMap: false,
+      noEmitOnError: true,
+      incremental: false,
+      composite: false,
+      declarationMap: false,
+      noUnusedLocals: false,
+    },
+    workingDirectory,
+    fileMap
+  );
+
+  const service = ts.createLanguageService(serviceHost, registry);
+
+  try {
+    const output = service.getEmitOutput(filename, false, false);
+
+    if (output.emitSkipped) {
+      const diagnostics = [
+        ...service.getSemanticDiagnostics(filename),
+        ...service.getSyntacticDiagnostics(filename),
+      ];
+
+      return {
+        diagnostics,
+        hasError: true,
+      };
+    }
+
+    return {
+      diagnostics: [],
+      hasError: false,
+    };
+  } finally {
+    service.dispose();
+  }
+};

src/LocalImportSubstituter.ts

@@ -101,21 +101,17 @@ class ExportResolver {
     );
   }
 
-  stripSuffix(filePath: string): string {
-    return filePath.replace(/\.(tsx?|js)$/, "");
-  }
-
   resolveExportPath(path?: string): string {
     if (!this.packageExports) {
       if (!this.packageMain) {
         throw new Error("Failed to find main or exports entry in package.json");
       }
 
-      return path ?? this.stripSuffix(this.packageMain);
+      return path ?? this.packageMain;
     }
 
     const matchingExport = this.findMatchingExport(path);
-    return this.stripSuffix(matchingExport);
+    return matchingExport;
   }
 }
 

src/PackageInfo.ts

@@ -1,5 +1,5 @@
 import * as path from "path";
-import * as fsExtra from "fs-extra";
+import { readFile } from "fs/promises";
 
 export type SubpathPattern = "." | string;
 
@@ -36,7 +36,7 @@ const searchParentsForPackage = async (
   currentPath: string
 ): Promise<string> => {
   try {
-    await fsExtra.readFile(path.join(currentPath, "package.json"));
+    await readFile(path.join(currentPath, "package.json"));
     return currentPath;
   } catch {
     const parentPath = path.dirname(currentPath);
@@ -60,7 +60,7 @@ export class PackageInfo {
   static async read(): Promise<PackageDefinition> {
     const packageRoot = await searchParentsForPackage(process.cwd());
     const packageJsonPath = path.join(packageRoot, "package.json");
-    const contents = await fsExtra.readFile(packageJsonPath, "utf-8");
+    const contents = await readFile(packageJsonPath, "utf-8");
     const packageInfo = JSON.parse(contents);
 
     return {