Implement selective typecheck

.changeset/tiny-parents-invent.md

@@ -0,0 +1,5 @@
+---
+'modular-scripts': minor
+---
+
+Add selective options to typecheck

__fixtures__/selective-typecheck-example/package.json

@@ -0,0 +1,60 @@
+{
+  "name": "selective-typecheck-example",
+  "version": "1.0.0",
+  "main": "index.js",
+  "author": "Sam Brown <sam.brown@jpmorgan.com>",
+  "license": "MIT",
+  "private": true,
+  "workspaces": [
+    "packages/**"
+  ],
+  "modular": {
+    "type": "root"
+  },
+  "scripts": {
+    "start": "modular start",
+    "build": "modular build",
+    "test": "modular test",
+    "lint": "eslint . --ext .js,.ts,.tsx",
+    "prettier": "prettier --write ."
+  },
+  "eslintConfig": {
+    "extends": "modular-app"
+  },
+  "browserslist": {
+    "production": [
+      ">0.2%",
+      "not dead",
+      "not op_mini all"
+    ],
+    "development": [
+      "last 1 chrome version",
+      "last 1 firefox version",
+      "last 1 safari version"
+    ]
+  },
+  "prettier": {
+    "singleQuote": true,
+    "trailingComma": "all",
+    "printWidth": 80,
+    "proseWrap": "always"
+  },
+  "dependencies": {
+    "@testing-library/dom": "^8.20.0",
+    "@testing-library/jest-dom": "^5.16.5",
+    "@testing-library/react": "^9.5.0",
+    "@testing-library/user-event": "^7.2.1",
+    "@types/jest": "^29.4.0",
+    "@types/node": "^18.14.6",
+    "@types/react": "^18.0.9",
+    "@types/react-dom": "^18.0.8",
+    "eslint-config-modular-app": "^4.0.0",
+    "modular-scripts": "^4.1.0",
+    "modular-template-app": "^1.2.0",
+    "modular-template-source": "^1.1.0",
+    "prettier": "^2.8.4",
+    "react": "^18.2.0",
+    "react-dom": "^18.2.0",
+    "typescript": "^4.8.3"
+  }
+}

__fixtures__/selective-typecheck-example/packages/common-module/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "selective-typecheck-common-module",
+  "private": false,
+  "modular": {
+    "type": "source"
+  },
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "version": "1.0.0"
+}

__fixtures__/selective-typecheck-example/packages/common-module/src/index.ts

@@ -0,0 +1,12 @@
+/* eslint-disable */
+
+// The following TS nocheck flag gets removed in test
+// @ts-nocheck
+
+export default function add(a: number, b: number): number {
+  return a + b + 'c';
+}
+
+export function otherThing(input) {
+  return typeof input;
+}

__fixtures__/selective-typecheck-example/packages/esbuild-app/.modular.js

@@ -0,0 +1,3 @@
+module.exports = {
+  useModularEsbuild: true,
+};

__fixtures__/selective-typecheck-example/packages/esbuild-app/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "app",
+  "private": true,
+  "modular": {
+    "type": "app"
+  },
+  "version": "1.0.0",
+  "dependencies": {
+    "selective-typecheck-common-module": "*"
+  }
+}

__fixtures__/selective-typecheck-example/packages/esbuild-app/src/App.tsx

@@ -0,0 +1,24 @@
+import React, { useEffect } from 'react';
+import './App.css';
+
+function App(): JSX.Element {
+  return (
+    <div className="App">
+      <header className="App-header">
+        <p>
+          Edit <code>src/App.tsx</code> and save to reload.
+        </p>
+        <a
+          className="App-link"
+          href="https://reactjs.org"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Learn React
+        </a>
+      </header>
+    </div>
+  );
+}
+
+export default App;

__fixtures__/selective-typecheck-example/packages/webpack-app/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "webpack-app",
+  "private": true,
+  "modular": {
+    "type": "app"
+  },
+  "version": "1.0.0",
+  "dependencies": {
+    "selective-typecheck-common-module": "*"
+  }
+}

__fixtures__/selective-typecheck-example/packages/webpack-app/src/App.tsx

@@ -0,0 +1,24 @@
+import * as React from 'react';
+import './App.css';
+
+function App(): JSX.Element {
+  return (
+    <div className="App">
+      <header className="App-header">
+        <p>
+          Edit <code>src/App.tsx</code> and save to reload.
+        </p>
+        <a
+          className="App-link"
+          href="https://reactjs.org"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Learn React
+        </a>
+      </header>
+    </div>
+  );
+}
+
+export default App;

docs/commands/typecheck.md

@@ -3,16 +3,66 @@ parent: Commands
 title: modular typecheck
 ---
 
-# `modular typecheck [options]`
+# `modular typecheck [options] [packages...]`
 
 `modular typecheck` will programmatically report the semantic, syntactic, and
-declaration type errors found in your code, based on your tsconfig.json.
+declaration type errors found in your code, based on your `tsconfig.json`.
 
 In a CI environment, it will print condensed errors if they are present.
 
 In non-CI environments, it will print the full details of the error, line, and
 small snapshot of the offending line in question.
 
+## Configuration
+
+`modular typecheck` will respect the root `tsconfig.json`, but most
+`compilerOptions` are ignored.
+
+It should be noted that `modular typecheck` does not support package-level
+`tsconfig.json` files, for backwards compatibility. Your IDE may still consume
+these, but it is recommended to keep your TypeScript configuration in the root
+`tsconfig.json`.
+
+_Why does Modular restrict compilerOptions?_
+
+`modular typecheck` aims to verify that the project's types are passing without
+errors. Certain TypeScript features such as emitting output are not useful in
+this scenario, so Modular has always applied a restricted set of
+`compilerOptions`.
+
+Although this approach has limited flexibility, it fits with Modular's goals and
+brings certain advantages:
+
+- Configuration is kept minimal and simple where possible
+- The possibility of incompatible or conflicting `compilerOptions` between
+  packages is avoided
+- It enables the use of selective `modular typecheck` (i.e. supply package names
+  and using flags such as `--ancestors`)
+
+There are certain exceptions for practical use cases. The current allowlist is:
+
+- [jsx](https://www.typescriptlang.org/tsconfig#jsx)
+
+Some use cases may warrant new exceptions. If this is you, please file an issue
+with the project for consideration.
+
 ## Options:
 
 `--verbose`: Enables verbose logging within modular
+
+`--descendants`: Typecheck the packages specified by the `[packages...]`
+argument and/or the `--changed` option and additionally typecheck all their
+descendants (i.e. the packages they directly or indirectly depend on).
+
+`--ancestors`: Typecheck the packages specified by the `[packages...]` argument
+and/or the `--changed` option and additionally typecheck all their ancestors
+(i.e. the packages that have a direct or indirect dependency on them).
+
+`--changed`: Typecheck only the packages whose workspaces contain files that
+have changed. Files that have changed are calculated comparing the current state
+of the repository with the branch specified by `compareBranch` or, if
+`compareBranch` is not set, with the default git branch.
+
+`--compareBranch`: Specify the comparison branch used to determine which files
+have changed when using the `changed` option. If this option is used without
+`changed`, the command will fail.