Add @ninjutsu-build/tsc.getEntryPointsFromConfig

Expose a function to return all TypeScript entry points as described by
a `tsconfig.json` file.  For all projects using a `tsconfig.json` file,
they will most likely have to use `getEntryPointsFromConfig` to get the
entry points in the configuration script if these entry points need to
be run later on and the users don't want to hardcode it.

integration/src/tsc.test.mts

@@ -1,7 +1,11 @@
 import { beforeEach, test, describe } from "node:test";
 import { strict as assert } from "node:assert";
 import { NinjaBuilder, getInput, validations } from "@ninjutsu-build/core";
-import { makeTSCRule, makeTypeCheckRule } from "@ninjutsu-build/tsc";
+import {
+  getEntryPointsFromConfig,
+  makeTSCRule,
+  makeTypeCheckRule,
+} from "@ninjutsu-build/tsc";
 import { writeFileSync, mkdirSync, symlinkSync, existsSync } from "node:fs";
 import { join } from "node:path/posix";
 import {
@@ -269,6 +273,10 @@ describe("tsc", (suiteCtx) => {
       "src/myOutput/script.mjs",
       "src/myOutput/script.d.mts",
     ]);
+    assert.deepEqual(
+      await getEntryPointsFromConfig(ninja, "src/tsconfig.json"),
+      ["src/script.mts"],
+    );
 
     const typechecked = await typecheck({
       tsConfig: { file: "src/tsconfig.json" },

packages/tsc/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@ninjutsu-build/tsc",
-  "version": "0.13.0",
+  "version": "0.13.1",
   "description": "Create a ninjutsu-build rule for running the TypeScript compiler (tsc)",
   "author": "Elliot Goodrich",
   "scripts": {

packages/tsc/src/tsc.ts

@@ -192,9 +192,57 @@ async function showConfig(
     join(ninja.outputDir, getInput(tsConfig)),
   ]);
 
+  // `--showConfig` displays valid JSON so use the built-in parser
   return JSON.parse(stdout);
 }
 
+/**
+ * Return the list of entry points specified in the `tsconfig.json` file
+ * located at the specified `tsConfigPath`.  This is a combination of
+ * the `files`, `include`, and `exclude` properties, see the
+ * [`tsconfig.json` documentation](https://www.typescriptlang.org/docs/handbook/tsconfig-json.html)
+ * for further information.
+ */
+export async function getEntryPointsFromConfig(
+  ninja: NinjaBuilder,
+  tsConfigPath: Input<string>,
+): Promise<string[]> {
+  const tsConfigPathRaw = join(ninja.outputDir, getInput(tsConfigPath));
+  const buffer = await readFile(tsConfigPathRaw);
+
+  // Use TypeScript's parsing to handle comments
+  let { config, error } = ts.parseConfigFileTextToJson(
+    tsConfigPathRaw,
+    buffer.toString(),
+  );
+  if (config === undefined) {
+    throw new Error(
+      error === undefined
+        ? `Unknown error while parsing ${tsConfigPathRaw}`
+        : `${error.messageText}`,
+    );
+  }
+
+  // If we don't have any `include` property then `files` gives us
+  // exactly the entry points we care about
+  if (Array.isArray(config.include) && config.include.length > 0) {
+    // There is no public typescript method to get the full list of entry points
+    // so instead we call out to `tsc --showConfig`.
+    const { stdout } = await execFile(node, [
+      tsc,
+      getTSCPath(ninja),
+      "--showConfig",
+      "--project",
+      tsConfigPathRaw,
+    ]);
+    // `--showConfig` displays valid JSON so use the built-in parser
+    config = JSON.parse(stdout);
+  }
+
+  const directory = dirname(getInput(tsConfigPath));
+  return config.files.map((f: string) => join(directory, f));
+}
+
 export type TypeCheckRuleFn = {
   <O extends string>(a: {
     in: readonly Input<string>[];