feat: add getProject

Author: velut

src/get-project.test.ts

@@ -0,0 +1,63 @@
+import { goTry } from "go-go-try";
+import fs from "node:fs/promises";
+import { join } from "pathe";
+import { expect, test } from "vitest";
+import { getProject } from "./get-project.ts";
+import { tempDir } from "./temp-dir.ts";
+
+test("no cwd", async () => {
+	await using dir = await tempDir();
+	const [err, _] = goTry(() =>
+		getProject({
+			indexFilePath: "./this-file-does-not-exist.ts",
+			typeRoots: join(dir.path, "this-dir-does-not-exist"),
+		}),
+	);
+	expect(err).toBeDefined();
+});
+
+test("no index file", async () => {
+	await using dir = await tempDir();
+	const [err, _] = goTry(() =>
+		getProject({
+			indexFilePath: "./this-file-does-not-exist.ts",
+			typeRoots: dir.path,
+		}),
+	);
+	expect(err).toBeDefined();
+});
+
+test("with index file", async () => {
+	await using dir = await tempDir();
+	const indexFilePath = join(dir.path, "./index.ts");
+	await fs.writeFile(indexFilePath, "export {};");
+	const [err, res] = goTry(() =>
+		getProject({
+			indexFilePath,
+			typeRoots: dir.path,
+		}),
+	);
+	expect(err).toBeUndefined();
+	expect(res).toBeDefined();
+	expect(res!.project.getSourceFiles().map((sf) => sf.getBaseName())).toStrictEqual(["index.ts"]);
+});
+
+test("with index file and other file", async () => {
+	await using dir = await tempDir();
+	const indexFilePath = join(dir.path, "./index.ts");
+	const otherFilePath = join(dir.path, "./other.ts");
+	await fs.writeFile(indexFilePath, "export * from './other';");
+	await fs.writeFile(otherFilePath, "export const a = 1;");
+	const [err, res] = goTry(() =>
+		getProject({
+			indexFilePath,
+			typeRoots: dir.path,
+		}),
+	);
+	expect(err).toBeUndefined();
+	expect(res).toBeDefined();
+	expect(res!.project.getSourceFiles().map((sf) => sf.getBaseName())).toStrictEqual([
+		"index.ts",
+		"other.ts",
+	]);
+});

src/get-project.ts

@@ -0,0 +1,55 @@
+import { ModuleKind, ModuleResolutionKind, Project, ScriptTarget, type SourceFile } from "ts-morph";
+
+/** `GetProjectOptions` contains the options for calling {@link getProject}. */
+export interface GetProjectOptions {
+	/** Path to the types entry point file. */
+	indexFilePath: string;
+
+	/**
+	Directory where the `@types` packages are installed.
+
+  @see {@link https://www.typescriptlang.org/tsconfig/#typeRoots}
+	*/
+	typeRoots: string;
+}
+
+/** `GetProjectReturn` contains the data returned by {@link getProject}. */
+export interface GetProjectReturn {
+	/** `Project` created with `ts-morph`. */
+	project: Project;
+
+	/** `SourceFile` created with `ts-morph` representing the index file. */
+	indexFile: SourceFile;
+}
+
+/** `getProject` returns a `ts-morph` TypeScript compiler project. */
+export function getProject({ indexFilePath, typeRoots }: GetProjectOptions): GetProjectReturn {
+	const project = new Project({
+		compilerOptions: {
+			// Include esnext types.
+			// See https://github.com/dsherret/ts-morph/issues/938
+			// and https://github.com/microsoft/TypeScript/blob/master/lib/lib.esnext.full.d.ts
+			lib: ["lib.esnext.full.d.ts"],
+
+			// Set modern target and module resolutions options.
+			target: ScriptTarget.ESNext,
+			module: ModuleKind.ESNext,
+			moduleResolution: ModuleResolutionKind.Bundler,
+
+			// By default, `ts-morph` creates a project rooted in the current working directory
+			// (that is, where this library or an app using it is running).
+			// We must change the `typeRoots` directory to the temporary directory where
+			// the analyzed package is installed, otherwise TypeScript will discover
+			// `@types` packages from our local `node_modules` directory giving
+			// inconsistent analysis results due to available type definitions.
+			// See https://www.typescriptlang.org/tsconfig#typeRoots.
+			typeRoots: [typeRoots],
+		},
+	});
+
+	// Add index file and resolve module imports.
+	const indexFile = project.addSourceFileAtPath(indexFilePath);
+	project.resolveSourceFileDependencies();
+
+	return { project, indexFile };
+}