feat(wrangler): apply d1 migrations with test harness

.changeset/gentle-ravens-apply.md

@@ -0,0 +1,15 @@
+---
+"wrangler": minor
+---
+
+Add D1 migration setup to `createTestHarness()` Worker handles
+
+Tests using `createTestHarness()` can now apply local D1 migrations before running requests:
+
+```ts
+const worker = server.getWorker();
+
+beforeEach(async () => {
+	await worker.applyD1Migrations("DATABASE");
+});
+```

.changeset/tidy-pandas-migrate.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/vite-plugin": patch
+---
+
+Preserve D1 migration paths in generated Worker configs
+
+When a Worker config with a D1 binding is built by the Vite plugin, the generated `wrangler.json` now points `migrations_dir` back to the source migration directory. This lets tools that read the generated config, such as `createTestHarness()`, find the same D1 migrations as the source Worker config.

fixtures/create-test-harness-example/README.md

@@ -8,17 +8,18 @@ For the testing patterns demonstrated here, refer to the [`createTestHarness()`
 
 The app has two Workers:
 
-| Worker       | Route                  | Role                                                                          |
-| ------------ | ---------------------- | ----------------------------------------------------------------------------- |
-| `web-worker` | `example.com/*`        | Handles user-facing routes and calls the API Worker over a service binding.   |
-| `api-worker` | `api.example.com/v1/*` | Fetches upstream user data, caches it in KV, and generates scheduled reports. |
+| Worker       | Route                  | Role                                                                             |
+| ------------ | ---------------------- | -------------------------------------------------------------------------------- |
+| `web-worker` | `example.com/*`        | Handles user-facing routes and calls the API Worker over a service binding.      |
+| `api-worker` | `api.example.com/v1/*` | Fetches upstream user data, caches it in KV, and stores scheduled reports in D1. |
 
 ## What this fixture covers
 
 - Setup [Vitest](https://vitest.dev/) against Workers developed with Wrangler.
 - Setup [Playwright](https://playwright.dev/) against Workers built by the Cloudflare Vite plugin.
 - Route dispatch across multiple Workers.
 - Direct Worker calls with `server.getWorker(name)`.
+- D1 migration setup with `worker.applyD1Migrations()`.
 - Scheduled handler dispatch.
 - Outbound request mocking with MSW.
 - Local storage reset between tests.
@@ -42,15 +43,15 @@ pnpm --filter @fixture/create-test-harness-example test:playwright
 
 ## Files
 
-| File                                                       | Purpose                                     |
-| ---------------------------------------------------------- | ------------------------------------------- |
-| [`tests/vitest.test.ts`](tests/vitest.test.ts)             | Example for testing with Vitest.            |
-| [`tests/playwright.test.ts`](tests/playwright.test.ts)     | Example for testing with Playwright.        |
-| [`vite.config.ts`](vite.config.ts)                         | Builds Vite-generated Worker configs.       |
-| [`workers/web/index.ts`](workers/web/index.ts)             | User-facing Worker.                         |
-| [`workers/web/wrangler.jsonc`](workers/web/wrangler.jsonc) | Web Worker config.                          |
-| [`workers/api/index.ts`](workers/api/index.ts)             | API Worker with KV and scheduled job logic. |
-| [`workers/api/wrangler.jsonc`](workers/api/wrangler.jsonc) | API Worker config.                          |
+| File                                                       | Purpose                                          |
+| ---------------------------------------------------------- | ------------------------------------------------ |
+| [`tests/vitest.test.ts`](tests/vitest.test.ts)             | Example for testing with Vitest.                 |
+| [`tests/playwright.test.ts`](tests/playwright.test.ts)     | Example for testing with Playwright.             |
+| [`vite.config.ts`](vite.config.ts)                         | Builds Vite-generated Worker configs.            |
+| [`workers/web/index.ts`](workers/web/index.ts)             | User-facing Worker.                              |
+| [`workers/web/wrangler.jsonc`](workers/web/wrangler.jsonc) | Web Worker config.                               |
+| [`workers/api/index.ts`](workers/api/index.ts)             | API Worker with KV, D1, and scheduled job logic. |
+| [`workers/api/wrangler.jsonc`](workers/api/wrangler.jsonc) | API Worker config.                               |
 
 ## Related docs
 

fixtures/create-test-harness-example/tests/playwright.test.ts

@@ -51,6 +51,8 @@ const test = base.extend<TestFixtures, WorkerFixtures>({
 
 	reset: [
 		async ({ network, server }, use, testInfo) => {
+			await server.getWorker("api-worker").applyD1Migrations("DATABASE");
+
 			await use();
 
 			if (testInfo.status !== testInfo.expectedStatus) {

fixtures/create-test-harness-example/tests/vitest.test.ts

@@ -1,6 +1,13 @@
 import { http, HttpResponse } from "msw";
 import { setupServer } from "msw/node";
-import { afterAll, afterEach, beforeAll, describe, test } from "vitest";
+import {
+	afterAll,
+	afterEach,
+	beforeAll,
+	beforeEach,
+	describe,
+	test,
+} from "vitest";
 import { createTestHarness } from "wrangler";
 
 // Point each worker to the Wrangler config you want to test.
@@ -25,6 +32,10 @@ describe("createTestHarness: Vitest setup", () => {
 		await server.listen();
 	});
 
+	beforeEach(async () => {
+		await apiWorker.applyD1Migrations("DATABASE");
+	});
+
 	afterAll(async () => {
 		network.close();
 		await server.close();

fixtures/create-test-harness-example/workers/api/index.ts

@@ -2,6 +2,7 @@ import { WorkerEntrypoint } from "cloudflare:workers";
 
 type Env = {
 	STORE: KVNamespace;
+	DATABASE: D1Database;
 };
 
 type User = {
@@ -47,9 +48,11 @@ export default class ApiWorker extends WorkerEntrypoint<Env> {
 		const list = await this.env.STORE.list({ prefix: "user/" });
 		const userIds = list.keys.map((key) => key.name.slice("user/".length));
 
-		await this.env.STORE.put(`daily-report/${date}`, JSON.stringify(userIds), {
-			expirationTtl: 60 * 60,
-		});
+		await this.env.DATABASE.prepare(
+			"INSERT OR REPLACE INTO daily_reports (date, user_ids) VALUES (?, ?)"
+		)
+			.bind(date, JSON.stringify(userIds))
+			.run();
 		console.info(`Generated daily report for ${date}`);
 
 		for (const key of list.keys) {
@@ -78,8 +81,17 @@ export default class ApiWorker extends WorkerEntrypoint<Env> {
 	}
 
 	async getDailyReport(date: string) {
-		return await this.env.STORE.get<string[]>(`daily-report/${date}`, {
-			type: "json",
-		});
+		const report = await this.env.DATABASE.prepare(
+			"SELECT user_ids FROM daily_reports WHERE date = ?"
+		)
+			.bind(date)
+			.first<{ user_ids: string }>();
+
+		if (report === null) {
+			return null;
+		}
+
+		const userIds: string[] = JSON.parse(report.user_ids);
+		return userIds;
 	}
 }

fixtures/create-test-harness-example/workers/api/migrations/0001_reports.sql

@@ -0,0 +1,4 @@
+CREATE TABLE daily_reports (
+	date TEXT PRIMARY KEY,
+	user_ids TEXT NOT NULL
+);

fixtures/create-test-harness-example/workers/api/wrangler.jsonc

@@ -4,4 +4,11 @@
 	"compatibility_date": "2026-06-01",
 	"routes": ["api.example.com/v1/*"],
 	"kv_namespaces": [{ "binding": "STORE", "id": "shared-store" }],
+	"d1_databases": [
+		{
+			"binding": "DATABASE",
+			"database_name": "report-database",
+			"database_id": "fake-database-id",
+		},
+	],
 }

packages/vite-plugin-cloudflare/src/plugins/output-config.ts

@@ -47,8 +47,41 @@ export const outputConfigPlugin = createPlugin("output-config", (ctx) => {
 					this.environment.name ===
 						ctx.resolvedPluginConfig.entryWorkerEnvironmentName;
 
+				const sourceConfigDirectory = path.dirname(
+					inputWorkerConfig.configPath ?? ctx.resolvedViteConfig.root
+				);
+				const outputDirectory = path.resolve(
+					ctx.resolvedViteConfig.root,
+					this.environment.config.build.outDir
+				);
+
 				outputConfig = {
 					...inputWorkerConfig,
+					d1_databases: inputWorkerConfig.d1_databases.map((database) => {
+						const sourceMigrationsDir = database.migrations_dir ?? "migrations";
+						const sourceMigrationsPath = path.resolve(
+							sourceConfigDirectory,
+							sourceMigrationsDir
+						);
+
+						if (!fs.existsSync(sourceMigrationsPath)) {
+							return database;
+						}
+
+						const outputMigrationsDir = vite.normalizePath(
+							path.relative(outputDirectory, sourceMigrationsPath) || "."
+						);
+
+						return {
+							...database,
+							migrations_dir: outputMigrationsDir,
+							migrations_pattern: rewriteMigrationsPattern(
+								database.migrations_pattern,
+								sourceMigrationsDir,
+								outputMigrationsDir
+							),
+						};
+					}),
 					main: entryChunk.fileName,
 					no_bundle: true,
 					rules: [{ type: "ESModule", globs: ["**/*.js", "**/*.mjs"] }],
@@ -153,6 +186,33 @@ export const outputConfigPlugin = createPlugin("output-config", (ctx) => {
 	};
 });
 
+function rewriteMigrationsPattern(
+	migrationsPattern: string | undefined,
+	fromMigrationsDir: string,
+	toMigrationsDir: string
+): string | undefined {
+	if (migrationsPattern === undefined) {
+		return undefined;
+	}
+
+	const normalizedDir = path.posix.normalize(
+		vite.normalizePath(fromMigrationsDir)
+	);
+	const normalizedPattern = path.posix.normalize(
+		vite.normalizePath(migrationsPattern)
+	);
+	const suffix =
+		normalizedDir === "."
+			? normalizedPattern
+			: path.posix.relative(normalizedDir, normalizedPattern);
+
+	return vite.normalizePath(
+		path.posix.normalize(
+			toMigrationsDir === "." ? suffix : `${toMigrationsDir}/${suffix}`
+		)
+	);
+}
+
 function readAssetsIgnoreFile(assetsIgnorePath: string): string {
 	const content = fs.existsSync(assetsIgnorePath)
 		? fs.readFileSync(assetsIgnorePath, "utf-8")

packages/wrangler/e2e/createTestHarness.test.ts

@@ -366,6 +366,86 @@ describe("createTestHarness", () => {
 		await expect(adminResponse.text()).resolves.toBe("2");
 	});
 
+	it("applies D1 migrations to a worker binding", async ({ expect }) => {
+		await helper.seed({
+			"wrangler.jsonc": dedent`
+				{
+					"name": "d1-worker",
+					"main": "src/index.ts",
+					"compatibility_date": "2026-05-20",
+					"d1_databases": [
+						{
+							"binding": "DATABASE",
+							"database_name": "test-database",
+							"database_id": "00000000-0000-0000-0000-000000000001",
+							"migrations_dir": "migrations",
+							"migrations_pattern": "migrations/*/migration.sql",
+							"migrations_table": "custom_migrations"
+						}
+					]
+				}
+			`,
+			"src/index.ts": dedent`
+				export default {
+					async fetch(request, env) {
+						const key = new URL(request.url).pathname.slice(1);
+						const row = await env.DATABASE.prepare("SELECT value FROM settings WHERE key = ?")
+							.bind(key)
+							.first();
+
+						if (row === null) {
+							return new Response("missing", { status: 404 });
+						}
+
+						return new Response(row.value);
+					}
+				};
+			`,
+			"migrations/0001_settings/migration.sql": dedent`
+				CREATE TABLE settings (
+					key TEXT PRIMARY KEY,
+					value TEXT NOT NULL
+				);
+			`,
+			"migrations/0002_seed/migration.sql": dedent`
+				INSERT INTO settings (key, value) VALUES ('greeting', 'Hello D1');
+			`,
+		});
+
+		const server = createTestHarness({
+			root: helper.tmpPath,
+			workers: [{ configPath: "./wrangler.jsonc" }],
+		});
+		onTestFinished(server.close);
+
+		await server.listen();
+
+		const worker = server.getWorker<{ DATABASE: D1Database }>();
+		await worker.applyD1Migrations("DATABASE");
+
+		const response = await worker.fetch("/greeting");
+		await expect(response.text()).resolves.toBe("Hello D1");
+
+		await worker.applyD1Migrations("DATABASE");
+		const secondResponse = await worker.fetch("/greeting");
+		await expect(secondResponse.text()).resolves.toBe("Hello D1");
+
+		server.debug();
+		const debugOutput = normalizeDebugOutput(logs.getAndClearOut());
+		expect(debugOutput).toContain(
+			"[server] [d1-worker] d1 migrations - DATABASE - applied 0001_settings/migration.sql"
+		);
+		expect(debugOutput).toContain(
+			"[server] [d1-worker] d1 migrations - DATABASE - applied 0002_seed/migration.sql"
+		);
+		expect(debugOutput).toContain(
+			"[server] [d1-worker] d1 migrations - DATABASE - completed (2 applied)"
+		);
+		expect(debugOutput).toContain(
+			"[server] [d1-worker] d1 migrations - DATABASE - completed (no migrations to apply)"
+		);
+	});
+
 	it("supports service bindings between workers", async ({ expect }) => {
 		await helper.seed({
 			"wrangler.primary.jsonc": dedent`

packages/wrangler/src/api/startDevWorker/ConfigController.ts

@@ -571,6 +571,7 @@ function getDevCompatibilityDate(
 
 export class ConfigController extends Controller {
 	latestInput?: StartDevWorkerInput;
+	latestWranglerConfig?: Config;
 	latestConfig?: StartDevWorkerOptions;
 	#printCurrentBindings?: (registry: WorkerRegistry | null) => void;
 
@@ -718,6 +719,7 @@ export class ConfigController extends Controller {
 			if (signal.aborted) {
 				return;
 			}
+			this.latestWranglerConfig = fileConfig;
 			this.latestConfig = resolvedConfig;
 			this.#printCurrentBindings = printCurrentBindings;
 			this.emitConfigUpdateEvent(resolvedConfig);