Allow composing register(create()); refactor tests

.vscode/launch.json

@@ -0,0 +1,16 @@
+{
+  "configurations": [
+    {
+      "name": "Debug AVA test file",
+      "type": "node",
+      "request": "launch",
+      "preLaunchTask": "npm: pre-debug",
+      "runtimeExecutable": "${workspaceFolder}/node_modules/.bin/ava",
+      "program": "${file}",
+      "outputCapture": "std",
+      "skipFiles": [
+        "<node_internals>/**/*.js"
+      ],
+    }
+  ],
+}

.vscode/tasks.json

@@ -0,0 +1,13 @@
+{
+  "tasks": [
+    {
+      "type": "npm",
+      "script": "pre-debug",
+      "problemMatcher": [
+        "$tsc"
+      ],
+      "label": "npm: pre-debug",
+      "detail": "npm run build-tsc && npm run build-pack"
+    }
+  ]
+}

package.json

@@ -67,6 +67,7 @@
     "test-cov": "nyc ava",
     "test": "npm run build && npm run lint && npm run test-cov --",
     "test-local": "npm run lint-fix && npm run build-tsc && npm run build-pack && npm run test-spec --",
+    "pre-debug": "npm run build-tsc && npm run build-pack",
     "coverage-report": "nyc report --reporter=lcov",
     "prepare": "npm run clean && npm run build-nopack",
     "api-extractor": "api-extractor run --local --verbose"

src/index.ts

@@ -427,10 +427,14 @@ export class TSError extends BaseError {
   }
 }
 
+const TS_NODE_SERVICE_BRAND = Symbol('TS_NODE_SERVICE_BRAND');
+
 /**
  * Primary ts-node service, which wraps the TypeScript API and can compile TypeScript to JavaScript
  */
 export interface Service {
+  /** @internal */
+  [TS_NODE_SERVICE_BRAND]: true;
   ts: TSCommon;
   config: _ts.ParsedCommandLine;
   options: RegisterOptions;
@@ -446,6 +450,8 @@ export interface Service {
   readonly shouldReplAwait: boolean;
   /** @internal */
   addDiagnosticFilter(filter: DiagnosticFilter): void;
+  /** @internal */
+  installSourceMapSupport(): void;
 }
 
 /**
@@ -477,12 +483,25 @@ export function getExtensions(config: _ts.ParsedCommandLine) {
   return { tsExtensions, jsExtensions };
 }
 
+/**
+ * Create a new TypeScript compiler instance and register it onto node.js
+ */
+export function register(opts?: RegisterOptions): Service;
 /**
  * Register TypeScript compiler instance onto node.js
  */
-export function register(opts: RegisterOptions = {}): Service {
+export function register(service: Service): Service;
+export function register(
+  serviceOrOpts: Service | RegisterOptions | undefined
+): Service {
+  // Is this a Service or a RegisterOptions?
+  let service = serviceOrOpts as Service;
+  if (!(serviceOrOpts as Service)?.[TS_NODE_SERVICE_BRAND]) {
+    // Not a service; is options
+    service = create((serviceOrOpts ?? {}) as RegisterOptions);
+  }
+
   const originalJsHandler = require.extensions['.js'];
-  const service = create(opts);
   const { tsExtensions, jsExtensions } = getExtensions(service.config);
   const extensions = [...tsExtensions, ...jsExtensions];
 
@@ -660,38 +679,41 @@ export function create(rawOptions: CreateOptions = {}): Service {
   }
 
   // Install source map support and read from memory cache.
-  sourceMapSupport.install({
-    environment: 'node',
-    retrieveFile(pathOrUrl: string) {
-      let path = pathOrUrl;
-      // If it's a file URL, convert to local path
-      // Note: fileURLToPath does not exist on early node v10
-      // I could not find a way to handle non-URLs except to swallow an error
-      if (options.experimentalEsmLoader && path.startsWith('file://')) {
-        try {
-          path = fileURLToPath(path);
-        } catch (e) {
-          /* swallow error */
+  installSourceMapSupport();
+  function installSourceMapSupport() {
+    sourceMapSupport.install({
+      environment: 'node',
+      retrieveFile(pathOrUrl: string) {
+        let path = pathOrUrl;
+        // If it's a file URL, convert to local path
+        // Note: fileURLToPath does not exist on early node v10
+        // I could not find a way to handle non-URLs except to swallow an error
+        if (options.experimentalEsmLoader && path.startsWith('file://')) {
+          try {
+            path = fileURLToPath(path);
+          } catch (e) {
+            /* swallow error */
+          }
         }
-      }
-      path = normalizeSlashes(path);
-      return outputCache.get(path)?.content || '';
-    },
-    redirectConflictingLibrary: true,
-    onConflictingLibraryRedirect(
-      request,
-      parent,
-      isMain,
-      options,
-      redirectedRequest
-    ) {
-      debug(
-        `Redirected an attempt to require source-map-support to instead receive @cspotcode/source-map-support.  "${
-          (parent as NodeJS.Module).filename
-        }" attempted to require or resolve "${request}" and was redirected to "${redirectedRequest}".`
-      );
-    },
-  });
+        path = normalizeSlashes(path);
+        return outputCache.get(path)?.content || '';
+      },
+      redirectConflictingLibrary: true,
+      onConflictingLibraryRedirect(
+        request,
+        parent,
+        isMain,
+        options,
+        redirectedRequest
+      ) {
+        debug(
+          `Redirected an attempt to require source-map-support to instead receive @cspotcode/source-map-support.  "${
+            (parent as NodeJS.Module).filename
+          }" attempted to require or resolve "${request}" and was redirected to "${redirectedRequest}".`
+        );
+      },
+    });
+  }
 
   const shouldHavePrettyErrors =
     options.pretty === undefined ? process.stdout.isTTY : options.pretty;
@@ -1239,6 +1261,7 @@ export function create(rawOptions: CreateOptions = {}): Service {
   }
 
   return {
+    [TS_NODE_SERVICE_BRAND]: true,
     ts,
     config,
     compile,
@@ -1250,6 +1273,7 @@ export function create(rawOptions: CreateOptions = {}): Service {
     moduleTypeClassifier,
     shouldReplAwait,
     addDiagnosticFilter,
+    installSourceMapSupport,
   };
 }
 

src/test/helpers.ts

@@ -12,9 +12,9 @@ import type { Readable } from 'stream';
  */
 import type * as tsNodeTypes from '../index';
 import type _createRequire from 'create-require';
-import { once } from 'lodash';
+import { has, once } from 'lodash';
 import semver = require('semver');
-import { isConstructSignatureDeclaration } from 'typescript';
+import * as expect from 'expect';
 const createRequire: typeof _createRequire = require('create-require');
 export { tsNodeTypes };
 
@@ -45,7 +45,7 @@ export const xfs = new NodeFS(fs);
 /** Pass to `test.context()` to get access to the ts-node API under test */
 export const contextTsNodeUnderTest = once(async () => {
   await installTsNode();
-  const tsNodeUnderTest = testsDirRequire('ts-node');
+  const tsNodeUnderTest: typeof tsNodeTypes = testsDirRequire('ts-node');
   return {
     tsNodeUnderTest,
   };
@@ -155,3 +155,63 @@ export function getStream(stream: Readable, waitForPattern?: string | RegExp) {
     combinedString = combinedBuffer.toString('utf8');
   }
 }
+
+const defaultRequireExtensions = captureObjectState(require.extensions);
+const defaultProcess = captureObjectState(process);
+const defaultModule = captureObjectState(require('module'));
+const defaultError = captureObjectState(Error);
+const defaultGlobal = captureObjectState(global);
+
+/**
+ * Undo all of ts-node & co's installed hooks, resetting the node environment to default
+ * so we can run multiple test cases which `.register()` ts-node.
+ *
+ * Must also play nice with `nyc`'s environmental mutations.
+ */
+export function resetNodeEnvironment() {
+  // We must uninstall so that it resets its internal state; otherwise it won't know it needs to reinstall in the next test.
+  require('@cspotcode/source-map-support').uninstall();
+
+  // Modified by ts-node hooks
+  resetObject(require.extensions, defaultRequireExtensions);
+
+  // ts-node attaches a property when it registers an instance
+  // source-map-support monkey-patches the emit function
+  resetObject(process, defaultProcess);
+
+  // source-map-support swaps out the prepareStackTrace function
+  resetObject(Error, defaultError);
+
+  // _resolveFilename is modified by tsconfig-paths, future versions of source-map-support, and maybe future versions of ts-node
+  resetObject(require('module'), defaultModule);
+
+  // May be modified by REPL tests, since the REPL sets globals.
+  resetObject(global, defaultGlobal);
+}
+
+function captureObjectState(object: any) {
+  return {
+    descriptors: Object.getOwnPropertyDescriptors(object),
+    values: { ...object },
+  };
+}
+// Redefine all property descriptors and delete any new properties
+function resetObject(
+  object: any,
+  state: ReturnType<typeof captureObjectState>
+) {
+  const currentDescriptors = Object.getOwnPropertyDescriptors(object);
+  for (const key of Object.keys(currentDescriptors)) {
+    if (!has(state.descriptors, key)) {
+      delete object[key];
+    }
+  }
+  // Trigger nyc's setter functions
+  for (const [key, value] of Object.entries(state.values)) {
+    try {
+      object[key] = value;
+    } catch {}
+  }
+  // Reset descriptors
+  Object.defineProperties(object, state.descriptors);
+}