refactor(std/example): Inconsistencies in the example tests (#7684)

std/examples/curl_test.ts

@@ -0,0 +1,43 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { serve } from "../http/server.ts";
+import { assertStrictEquals } from "../testing/asserts.ts";
+import { dirname, fromFileUrl } from "../path/mod.ts";
+
+const moduleDir = dirname(fromFileUrl(import.meta.url));
+
+Deno.test({
+  name: "[examples/curl] send a request to a specified url",
+  fn: async () => {
+    const server = serve({ port: 8081 });
+    const serverPromise = (async (): Promise<void> => {
+      for await (const req of server) {
+        req.respond({ body: "Hello world" });
+      }
+    })();
+
+    const decoder = new TextDecoder();
+    const process = Deno.run({
+      cmd: [
+        Deno.execPath(),
+        "run",
+        "--allow-net",
+        "curl.ts",
+        "http://localhost:8081",
+      ],
+      cwd: moduleDir,
+      stdout: "piped",
+    });
+
+    try {
+      const output = await process.output();
+      const actual = decoder.decode(output).trim();
+      const expected = "Hello world";
+
+      assertStrictEquals(actual, expected);
+    } finally {
+      server.close();
+      process.close();
+      await serverPromise;
+    }
+  },
+});