Implement next dev server and tests.

WORKSPACE

@@ -102,13 +102,12 @@ rules_js_dependencies()
 
 load("@rules_nodejs//nodejs:repositories.bzl", "DEFAULT_NODE_VERSION", "nodejs_register_toolchains")
 
-
 # force node version to be above 18
 # this should eventually be loaded from package.json engines.
 
 nodejs_register_toolchains(
     name = "nodejs",
-    node_version = DEFAULT_NODE_VERSION if int(DEFAULT_NODE_VERSION.split(".")[0]) > 18 else "18.13.0"
+    node_version = DEFAULT_NODE_VERSION if int(DEFAULT_NODE_VERSION.split(".")[0]) > 18 else "18.13.0",
 )
 
 load("@aspect_rules_js//npm:npm_import.bzl", "npm_translate_lock")

ts/next.js/rules.bzl

@@ -68,6 +68,12 @@ def next_project(name, srcs, **kwargs):
         output_dir = True,
     )
 
+    bin.next_binary(
+        name = "dev",
+        data = srcs,
+        args = ["dev", native.package_name()],
+    )
+
     bin.next(
         name = "out",
         srcs = [":build"] + srcs,

ts/next.js/testing/example/BUILD.bazel

@@ -1,4 +1,4 @@
-load("//ts:rules.bzl", "ts_project")
+load("//ts:rules.bzl", "jest_test", "ts_project")
 load("//ts/next.js:rules.bzl", "next_project")
 load("@npm//:next/package_json.bzl", next = "bin")
 
@@ -10,6 +10,7 @@ ts_project(
         "//:node_modules/@types/react",
         "//:node_modules/react",
         "//:node_modules/react-dom",
+        "//ts",
         "//ts/math",
     ],
 )
@@ -18,3 +19,16 @@ next_project(
     name = "example",
     srcs = [":ts_sources"],
 )
+
+jest_test(
+    name = "test_running_dev_server",
+    srcs = ["launch_server_test.js"],
+    data = [
+        ":dev",
+        ":ts_sources",
+    ],
+    env = {
+        "NEXT_SERVER_BINARY": "../../../$(location :dev)",
+        "BAZEL_BINDIR": "$(BINDIR)",
+    },
+)

ts/next.js/testing/example/launch_server_test.ts

@@ -0,0 +1,41 @@
+import child_process from 'node:child_process';
+import http from 'node:http';
+import * as readline from 'node:readline/promises';
+
+import { isDefined, isNotNull, must } from 'ts/guard';
+
+test('next.js dev server launch!', async () => {
+	const next_server_binary = 'ts/next.js/testing/example/dev.sh';
+	const BAZEL_BINDIR = must(isDefined)(process?.env?.BAZEL_BINDIR);
+
+	const proc = child_process.execFile(next_server_binary, {
+		env: { BAZEL_BINDIR },
+	});
+
+	console.info('Waiting for process to go up...');
+
+	await new Promise((ok, err) => {
+		proc.once('error', err);
+		proc.once('spawn', ok);
+	});
+
+	const output: NodeJS.WritableStream = must(isNotNull)(proc.stdin);
+	const input: NodeJS.ReadableStream = must(isNotNull)(proc.stdout);
+
+	for await (const line of readline.createInterface({
+		input, // not really needed, we're not asking Qs.
+		output,
+	})) {
+		console.info(line);
+		const m = /https:\/\/localhost:\d+/g.exec(line);
+		if (m?.[0]) {
+			// attempt to connect to the port
+			const resp: http.IncomingMessage = await new Promise(ok =>
+				http.get(m?.[0], resp => ok(resp))
+			);
+			expect(resp.statusCode).toBe(200);
+
+			break;
+		}
+	}
+});