feat: std/node (#3319)

std/node/fs_test.ts

@@ -0,0 +1,47 @@
+import { readFile, readFileSync } from "./fs.ts";
+import { test } from "../testing/mod.ts";
+import * as path from "../path/mod.ts";
+import { assertEquals, assert } from "../testing/asserts.ts";
+
+const testData = path.resolve(path.join("node", "testdata", "hello.txt"));
+
+// Need to convert to promises, otherwise test() won't report error correctly.
+test(async function readFileSuccess() {
+  const data = await new Promise((res, rej) => {
+    readFile(testData, (err, data) => {
+      if (err) {
+        rej(err);
+      }
+      res(data);
+    });
+  });
+
+  assert(data instanceof Uint8Array);
+  assertEquals(new TextDecoder().decode(data as Uint8Array), "hello world");
+});
+
+test(async function readFileEncodeUtf8Success() {
+  const data = await new Promise((res, rej) => {
+    readFile(testData, { encoding: "utf8" }, (err, data) => {
+      if (err) {
+        rej(err);
+      }
+      res(data);
+    });
+  });
+
+  assertEquals(typeof data, "string");
+  assertEquals(data as string, "hello world");
+});
+
+test(function readFileSyncSuccess() {
+  const data = readFileSync(testData);
+  assert(data instanceof Uint8Array);
+  assertEquals(new TextDecoder().decode(data as Uint8Array), "hello world");
+});
+
+test(function readFileEncodeUtf8Success() {
+  const data = readFileSync(testData, { encoding: "utf8" });
+  assertEquals(typeof data, "string");
+  assertEquals(data as string, "hello world");
+});