chore: update lint rules, add tests

web/eslint-plugins/__tests__/no-mixed-imports.test.ts

@@ -0,0 +1,102 @@
+// Tests for the isolation rule (web/eslint-plugins/isolation/no-mixed-imports.js).
+//
+// The rule RESOLVES import specifiers to real files (via $lib alias and
+// relative ../ paths), so every import target must exist on disk. It therefore
+// runs through the Linter API with cwd pinned to the committed fixture tree
+// (__fixtures__/src) — see __tests__/helpers.ts.
+//
+// Side map (mirrors the defaults in no-mixed-imports.js):
+//   old   -> routes/v1/**, lib/v1/**
+//   new   -> routes/** (minus v1), lib/components/**, lib/registry/** + a few
+//   shared-> everything else: core/, i18n/, theme, ...
+import { describe, expect, it } from "vitest";
+import noMixedImports from "../isolation/no-mixed-imports.js";
+import { verifyInFixtures, type FlatConfig } from "./helpers.js";
+
+const isolationConfig: FlatConfig = [
+	{
+		files: ["**/*.{ts,svelte}"],
+		plugins: { isolation: { rules: { "no-mixed-imports": noMixedImports } } },
+		rules: { "isolation/no-mixed-imports": "error" },
+	},
+];
+
+const messagesFor = (relFile: string, code: string) =>
+	verifyInFixtures(isolationConfig, code, relFile);
+
+/** Assert a single "noMixed" violation with the given sides. */
+function expectViolation(
+	relFile: string,
+	code: string,
+	side: string,
+	target: string,
+) {
+	const messages = messagesFor(relFile, code);
+	expect(messages).toHaveLength(1);
+	expect(messages[0].messageId).toBe("noMixed");
+	// ESLint interpolates `data` into the message text (no `data` field on the
+	// returned message), so assert on the rendered message instead.
+	expect(messages[0].message).toContain(`"${side}" file imports "${target}"`);
+}
+
+/** Assert the import is allowed (no violations). */
+function expectClean(relFile: string, code: string) {
+	expect(messagesFor(relFile, code)).toEqual([]);
+}
+
+describe("isolation/no-mixed-imports", () => {
+	it("flags an old file importing a new component", () => {
+		expectViolation(
+			"lib/v1/old.ts",
+			'import { c } from "../components/CheckerCanvas.svelte";',
+			"old",
+			"new",
+		);
+	});
+
+	it("flags a new route importing an old module through the $lib alias", () => {
+		expectViolation(
+			"routes/+page.svelte",
+			'import { o } from "$lib/v1/old";',
+			"new",
+			"old",
+		);
+	});
+
+	it("flags a new component importing old code via a relative path", () => {
+		expectViolation(
+			"lib/components/CheckerCanvas.svelte",
+			'import { o } from "../v1/old.ts";',
+			"new",
+			"old",
+		);
+	});
+
+	it("allows old -> shared (core via relative path)", () => {
+		expectClean("lib/v1/old.ts", 'import { e } from "../core/errors";');
+	});
+
+	it("allows old -> shared (i18n and theme via $lib)", () => {
+		expectClean("routes/v1/+layout.svelte", 'import { t } from "$lib/i18n/t";');
+		expectClean(
+			"routes/v1/+layout.svelte",
+			'import { g } from "$lib/theme.svelte";',
+		);
+	});
+
+	it("allows new -> shared and new -> new", () => {
+		expectClean("routes/+page.svelte", 'import { t } from "$lib/i18n/t";');
+		expectClean(
+			"routes/+page.svelte",
+			'import { b } from "$lib/components/ui/Button.svelte";',
+		);
+	});
+
+	it("leaves shared files unrestricted in both directions", () => {
+		expectClean("lib/i18n/t.ts", 'import { o } from "$lib/v1/old";');
+		expectClean(
+			"lib/core/errors.ts",
+			'import { c } from "$lib/components/CheckerCanvas.svelte";',
+		);
+	});
+});