refactor: Graph analysis - unit testing

.changeset/lovely-sloths-flow.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[chore] Refactor graph analysis for better unit tests

packages/kit/src/exports/vite/dev/index.js

@@ -11,7 +11,7 @@ import { load_error_page, load_template } from '../../../core/config/index.js';
 import { SVELTE_KIT_ASSETS } from '../../../constants.js';
 import * as sync from '../../../core/sync/sync.js';
 import { get_mime_lookup, runtime_base, runtime_prefix } from '../../../core/utils.js';
-import { prevent_illegal_vite_imports } from '../utils.js';
+import { prevent_illegal_vite_imports } from '../graph_analysis/index.js';
 import { compact } from '../../../utils/array.js';
 import { normalizePath } from 'vite';
 

packages/kit/src/exports/vite/graph_analysis/index.js

@@ -0,0 +1,277 @@
+import path from 'path';
+import { normalizePath } from 'vite';
+import { remove_query_from_id, get_module_types } from './utils.js';
+
+/** @typedef {import('./types').ImportGraph} ImportGraph */
+
+const CWD_ID = normalizePath(process.cwd());
+const NODE_MODULES_ID = normalizePath(path.resolve(process.cwd(), 'node_modules'));
+const ILLEGAL_IMPORTS = new Set([
+	'/@id/__x00__$env/dynamic/private', //dev
+	'\0$env/dynamic/private', // prod
+	'/@id/__x00__$env/static/private', // dev
+	'\0$env/static/private' // prod
+]);
+const ILLEGAL_MODULE_NAME_PATTERN = /.*\.server\..+/;
+
+export class IllegalModuleGuard {
+	/** @type {string} */
+	#lib_dir;
+
+	/** @type {string} */
+	#server_dir;
+
+	/** @type {Array<ImportGraph>} */
+	#chain = [];
+
+	/**
+	 * @param {string} lib_dir
+	 */
+	constructor(lib_dir) {
+		this.#lib_dir = normalizePath(lib_dir);
+		this.#server_dir = normalizePath(path.resolve(lib_dir, 'server'));
+	}
+
+	/**
+	 * Assert that a node imports no illegal modules.
+	 * @param {ImportGraph} node
+	 * @returns {void}
+	 */
+	assert_legal(node) {
+		this.#chain.push(node);
+		for (const child of node.children) {
+			if (this.#is_illegal(child.id)) {
+				this.#chain.push(child);
+				const error = this.#format_illegal_import_chain(this.#chain);
+				this.#chain = []; // Reset the chain in case we want to reuse this guard
+				throw new Error(error);
+			}
+			this.assert_legal(child);
+		}
+		this.#chain.pop();
+	}
+
+	/**
+	 * `true` if the provided ID represents a server-only module, else `false`.
+	 * @param {string} module_id
+	 * @returns {boolean}
+	 */
+	#is_illegal(module_id) {
+		if (this.#is_kit_illegal(module_id) || this.#is_user_illegal(module_id)) return true;
+		return false;
+	}
+
+	/**
+	 * `true` if the provided ID represents a Kit-defined server-only module, else `false`.
+	 * @param {string} module_id
+	 * @returns {boolean}
+	 */
+	#is_kit_illegal(module_id) {
+		return ILLEGAL_IMPORTS.has(module_id);
+	}
+
+	/**
+	 * `true` if the provided ID represents a user-defined server-only module, else `false`.
+	 * @param {string} module_id
+	 * @returns {boolean}
+	 */
+	#is_user_illegal(module_id) {
+		if (module_id.startsWith(this.#server_dir)) return true;
+
+		// files outside the project root are ignored
+		if (!module_id.startsWith(CWD_ID)) return false;
+
+		// so are files inside node_modules
+		if (module_id.startsWith(NODE_MODULES_ID)) return false;
+
+		return ILLEGAL_MODULE_NAME_PATTERN.test(path.basename(module_id));
+	}
+
+	/**
+	 * @param {string} str
+	 * @param {number} times
+	 */
+	#repeat(str, times) {
+		return new Array(times + 1).join(str);
+	}
+
+	/**
+	 * Create a formatted error for an illegal import.
+	 * @param {Array<ImportGraph>} stack
+	 */
+	#format_illegal_import_chain(stack) {
+		const dev_virtual_prefix = '/@id/__x00__';
+		const prod_virtual_prefix = '\0';
+
+		stack = stack.map((graph) => {
+			if (graph.id.startsWith(dev_virtual_prefix)) {
+				return { ...graph, id: graph.id.replace(dev_virtual_prefix, '') };
+			}
+			if (graph.id.startsWith(prod_virtual_prefix)) {
+				return { ...graph, id: graph.id.replace(prod_virtual_prefix, '') };
+			}
+			if (graph.id.startsWith(this.#lib_dir)) {
+				return { ...graph, id: graph.id.replace(this.#lib_dir, '$lib') };
+			}
+
+			return { ...graph, id: path.relative(process.cwd(), graph.id) };
+		});
+
+		const pyramid = stack
+			.map(
+				(file, i) =>
+					`${this.#repeat(' ', i * 2)}- ${file.id} ${
+						file.dynamic ? '(imported by parent dynamically)' : ''
+					}`
+			)
+			.join('\n');
+
+		return `Cannot import ${stack.at(-1)?.id} into client-side code:\n${pyramid}`;
+	}
+}
+
+/** @implements {ImportGraph} */
+export class RollupImportGraph {
+	/** @type {(id: string) => import('rollup').ModuleInfo | null} */
+	#node_getter;
+
+	/** @type {import('rollup').ModuleInfo} */
+	#module_info;
+
+	/** @type {string} */
+	id;
+
+	/** @type {boolean} */
+	dynamic;
+
+	/** @type {Set<string>} */
+	#seen;
+
+	/**
+	 * @param {(id: string) => import('rollup').ModuleInfo | null} node_getter
+	 * @param {import('rollup').ModuleInfo} node
+	 */
+	constructor(node_getter, node) {
+		this.#node_getter = node_getter;
+		this.#module_info = node;
+		this.id = remove_query_from_id(normalizePath(node.id));
+		this.dynamic = false;
+		this.#seen = new Set();
+	}
+
+	/**
+	 * @param {(id: string) => import('rollup').ModuleInfo | null} node_getter
+	 * @param {import('rollup').ModuleInfo} node
+	 * @param {boolean} dynamic
+	 * @param {Set<string>} seen;
+	 * @returns {RollupImportGraph}
+	 */
+	static #new_internal(node_getter, node, dynamic, seen) {
+		const instance = new RollupImportGraph(node_getter, node);
+		instance.dynamic = dynamic;
+		instance.#seen = seen;
+		return instance;
+	}
+
+	get children() {
+		return this.#children();
+	}
+
+	*#children() {
+		if (this.#seen.has(this.id)) return;
+		this.#seen.add(this.id);
+		for (const id of this.#module_info.importedIds) {
+			const child = this.#node_getter(id);
+			if (child === null) return;
+			yield RollupImportGraph.#new_internal(this.#node_getter, child, false, this.#seen);
+		}
+		for (const id of this.#module_info.dynamicallyImportedIds) {
+			const child = this.#node_getter(id);
+			if (child === null) return;
+			yield RollupImportGraph.#new_internal(this.#node_getter, child, true, this.#seen);
+		}
+	}
+}
+
+/** @implements {ImportGraph} */
+export class ViteImportGraph {
+	/** @type {Set<string>} */
+	#module_types;
+
+	/** @type {import('vite').ModuleNode} */
+	#module_info;
+
+	/** @type {string} */
+	id;
+
+	/** @type {Set<string>} */
+	#seen;
+
+	/**
+	 * @param {Set<string>} module_types Module types to analyze, eg '.js', '.ts', etc.
+	 * @param {import('vite').ModuleNode} node
+	 */
+	constructor(module_types, node) {
+		this.#module_types = module_types;
+		this.#module_info = node;
+		this.id = remove_query_from_id(normalizePath(node.id ?? ''));
+		this.#seen = new Set();
+	}
+
+	/**
+	 * @param {Set<string>} module_types Module types to analyze, eg '.js', '.ts', etc.
+	 * @param {import('vite').ModuleNode} node
+	 * @param {Set<string>} seen
+	 * @returns {ViteImportGraph}
+	 */
+	static #new_internal(module_types, node, seen) {
+		const instance = new ViteImportGraph(module_types, node);
+		instance.#seen = seen;
+		return instance;
+	}
+
+	get dynamic() {
+		return false;
+	}
+
+	get children() {
+		return this.#children();
+	}
+
+	*#children() {
+		if (this.#seen.has(this.id)) return;
+		this.#seen.add(this.id);
+		for (const child of this.#module_info.importedModules) {
+			if (!this.#module_types.has(path.extname(this.id))) {
+				continue;
+			}
+			yield ViteImportGraph.#new_internal(this.#module_types, child, this.#seen);
+		}
+	}
+}
+
+/**
+ * Throw an error if a private module is imported from a client-side node.
+ * @param {(id: string) => import('rollup').ModuleInfo | null} node_getter
+ * @param {import('rollup').ModuleInfo} node
+ * @param {string} lib_dir
+ * @returns {void}
+ */
+export function prevent_illegal_rollup_imports(node_getter, node, lib_dir) {
+	const graph = new RollupImportGraph(node_getter, node);
+	const guard = new IllegalModuleGuard(lib_dir);
+	guard.assert_legal(graph);
+}
+
+/**
+ * Throw an error if a private module is imported from a client-side node.
+ * @param {import('vite').ModuleNode} node
+ * @param {string} lib_dir
+ * @param {Iterable<string>} module_types File extensions to analyze in addition to the defaults: `.ts`, `.js`, etc.
+ * @returns {void}
+ */
+export function prevent_illegal_vite_imports(node, lib_dir, module_types) {
+	const graph = new ViteImportGraph(get_module_types(module_types), node);
+	const guard = new IllegalModuleGuard(lib_dir);
+	guard.assert_legal(graph);
+}