breaking: Make typescript an optional dependency.

package.json

@@ -68,7 +68,8 @@
     "@types/react": "^16.9.56",
     "@types/rimraf": "^3.0.0",
     "@types/semver": "^7.3.4",
-    "chokidar": "^3.5.1"
+    "chokidar": "^3.5.1",
+    "typescript": "^4.1.3"
   },
   "dependencies": {
     "@babel/core": "^7.12.13",
@@ -104,10 +105,10 @@
     "rollup-plugin-polyfill-node": "^0.5.0",
     "rollup-plugin-visualizer": "^4.2.0",
     "semver": "^7.3.4",
-    "spdx-license-list": "^6.4.0",
-    "typescript": "^4.1.3"
+    "spdx-license-list": "^6.4.0"
   },
   "optionalDependencies": {
-    "chokidar": "^3.5.1"
+    "chokidar": "^3.5.1",
+    "typescript": "^4.1.3"
   }
 }

src/Package.ts

@@ -1,11 +1,11 @@
 /* eslint-disable require-atomic-updates, no-param-reassign, @typescript-eslint/member-ordering */
 
 import fs from 'fs-extra';
-import ts from 'typescript';
 import { Memoize, optimal, Path, toArray } from '@boost/common';
 import { createDebugger, Debugger } from '@boost/debug';
 import Artifact from './Artifact';
 import { FORMATS_BROWSER, FORMATS_NATIVE, FORMATS_NODE } from './constants';
+import { loadModule } from './helpers/loadModule';
 import Project from './Project';
 import { packemonBlueprint } from './schemas';
 import {
@@ -232,6 +232,11 @@ export default class Package {
       return undefined;
     }
 
+    const ts = loadModule(
+      'typescript',
+      'TypeScript is required for config loading.',
+    ) as typeof import('typescript');
+
     // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
     const { config, error } = ts.readConfigFile(tsconfigJsonPath.path(), (name) =>
       fs.readFileSync(name, 'utf8'),

src/TypesArtifact.ts

@@ -1,12 +1,11 @@
 import path from 'path';
 import glob from 'fast-glob';
 import fs from 'fs-extra';
-import { ParsedCommandLine } from 'typescript';
 import { Path } from '@boost/common';
 import { createDebugger, Debugger } from '@boost/debug';
 import { Extractor, ExtractorConfig } from '@microsoft/api-extractor';
 import Artifact from './Artifact';
-import { APIExtractorStructure, DeclarationType, TypesBuild } from './types';
+import { APIExtractorStructure, DeclarationType, TSConfigStructure, TypesBuild } from './types';
 
 // eslint-disable-next-line
 const extractorConfig = require(path.join(__dirname, '../api-extractor.json')) as {
@@ -167,7 +166,7 @@ export default class TypesArtifact extends Artifact<TypesBuild> {
 
   // This method only exists so that we can mock in tests.
   // istanbul ignore next
-  protected loadTsconfigJson(): ParsedCommandLine | undefined {
+  protected loadTsconfigJson(): TSConfigStructure | undefined {
     return this.package.tsconfigJson;
   }
 

src/commands/Watch.tsx

@@ -1,5 +1,6 @@
 import { applyStyle, Arg, Config } from '@boost/cli';
 import { Bind, formatMs } from '@boost/common';
+import { loadModule } from '../helpers/loadModule';
 import Package from '../Package';
 import { BaseCommand } from './Base';
 
@@ -26,7 +27,10 @@ export class WatchCommand extends BaseCommand<WatchOptions> {
 
   async run() {
     const { packemon } = this;
-    const chokidar = this.loadChokidar() as typeof import('chokidar');
+    const chokidar = loadModule(
+      'chokidar',
+      'Chokidar is required for file watching.',
+    ) as typeof import('chokidar');
 
     packemon.debug('Starting `watch` process');
 
@@ -70,17 +74,6 @@ export class WatchCommand extends BaseCommand<WatchOptions> {
     }
   }
 
-  loadChokidar(): unknown {
-    try {
-      // eslint-disable-next-line global-require, import/no-extraneous-dependencies
-      return require('chokidar');
-    } catch {
-      throw new Error(
-        'Chokidar is required for file watching. Please install with `yarn add --dev chokidar`.',
-      );
-    }
-  }
-
   triggerRebuilds() {
     if (this.rebuildTimer) {
       clearTimeout(this.rebuildTimer);

src/helpers/loadModule.ts

@@ -0,0 +1,8 @@
+export function loadModule(name: string, message: string): unknown {
+  try {
+    // eslint-disable-next-line
+    return require(name);
+  } catch {
+    throw new Error(`${message} Please install with \`yarn add --dev ${name}\`.`);
+  }
+}

src/types.ts

@@ -1,6 +1,5 @@
 /* eslint-disable no-underscore-dangle */
 
-import ts from 'typescript';
 import { PackageStructure } from '@boost/common';
 
 // Platform = The runtime or operating system the code will run in.
@@ -145,7 +144,14 @@ declare module 'rollup' {
 
 export type Awaitable = Promise<void> | void;
 
-export type TSConfigStructure = ts.ParsedCommandLine;
+export interface TSConfigStructure {
+  options: {
+    declarationDir?: string;
+    experimentalDecorators?: boolean;
+    outDir?: string;
+    strict?: boolean;
+  };
+}
 
 export interface APIExtractorStructure {
   projectFolder: string;

tests/helpers/loadModule.test.ts

@@ -0,0 +1,13 @@
+import { loadModule } from '../../src/helpers/loadModule';
+
+describe('loadModule()', () => {
+  it('doesnt error if module exists', () => {
+    expect(() => loadModule('typescript', '')).not.toThrow();
+  });
+
+  it('errors if module does not exist', () => {
+    expect(() => loadModule('unknown-module', 'Fake module!')).toThrow(
+      'Fake module! Please install with `yarn add --dev unknown-module`.',
+    );
+  });
+});