fix: treat a file where a watched directory should be like a missing directory

.changeset/missing-under-file.md

@@ -0,0 +1,5 @@
+---
+"watchpack": patch
+---
+
+Watch a missing file whose parent path is a file (e.g. `src/foo/index.js`, tried by a resolver alias, while `src/foo` is a file) like one whose parent is missing: no more `ENOTDIR` "Watchpack Error (initial scan)" log, and the file is reported once the parent becomes a directory (fixes #226's case).

lib/DirectoryWatcher.js

@@ -904,6 +904,9 @@ class DirectoryWatcher extends EventEmitter {
 					// (see #187).
 					if (
 						err.code === "ENOENT" ||
+						// a file where the directory should be, e.g. `src/foo` for a
+						// missing `src/foo/index.js` that a resolver tried (#226)
+						err.code === "ENOTDIR" ||
 						err.code === "EPERM" ||
 						err.code === "EACCES" ||
 						err.code === "ENODEV" ||

test/MissingUnderFile.test.js

@@ -0,0 +1,50 @@
+"use strict";
+
+const path = require("path");
+const Watchpack = require("../lib");
+const TestHelper = require("./helpers/TestHelper");
+
+const fixtures = path.join(__dirname, "fixtures");
+const testHelper = new TestHelper(fixtures);
+
+// eslint-disable-next-line jest/no-confusing-set-timeout
+jest.setTimeout(20000);
+
+describe("Missing file below a path that is a file (#226)", () => {
+	beforeEach((done) => {
+		testHelper.before(done);
+	});
+
+	/** @type {InstanceType<typeof Watchpack>[]} */
+	let watchers = [];
+
+	afterEach((done) => {
+		// closed here, not in the test, so a failure cannot leave one running
+		for (const w of watchers) w.close();
+		watchers = [];
+		jest.restoreAllMocks();
+		testHelper.after(done);
+	});
+
+	it("should report the file once its parent turns from a file into a directory", (done) => {
+		// a resolver tried `foo/index.js` while `foo` is a file
+		testHelper.file("foo");
+		const missing = path.join(fixtures, "foo", "index.js");
+		const errors = jest.spyOn(console, "error").mockImplementation(() => {});
+		testHelper.tick(1000, () => {
+			const w = new Watchpack({ aggregateTimeout: 100 });
+			watchers.push(w);
+			w.on("change", (item) => {
+				expect(item).toBe(missing);
+				expect(errors).not.toHaveBeenCalled();
+				done();
+			});
+			w.watch({ missing: [missing], startTime: Date.now() });
+			testHelper.tick(1000, () => {
+				testHelper.remove("foo");
+				testHelper.dir("foo");
+				testHelper.file(path.join("foo", "index.js"));
+			});
+		});
+	});
+});