1 files changed, 80 insertions, 0 deletions
diff --git a/cli/js/tests/truncate_test.ts b/cli/js/tests/truncate_test.ts
new file mode 100644
index 000000000..3fd85c990
--- /dev/null
+++ b/cli/js/tests/truncate_test.ts
@@ -0,0 +1,80 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { unitTest, assertEquals, assert } from "./test_util.ts";
+
+function readDataSync(name: string): string {
+  const data = Deno.readFileSync(name);
+  const decoder = new TextDecoder("utf-8");
+  const text = decoder.decode(data);
+  return text;
+}
+
+async function readData(name: string): Promise<string> {
+  const data = await Deno.readFile(name);
+  const decoder = new TextDecoder("utf-8");
+  const text = decoder.decode(data);
+  return text;
+}
+
+unitTest(
+  { perms: { read: true, write: true } },
+  function truncateSyncSuccess(): void {
+    const enc = new TextEncoder();
+    const d = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test_truncateSync.txt";
+    Deno.writeFileSync(filename, d);
+    Deno.truncateSync(filename, 20);
+    let data = readDataSync(filename);
+    assertEquals(data.length, 20);
+    Deno.truncateSync(filename, 5);
+    data = readDataSync(filename);
+    assertEquals(data.length, 5);
+    Deno.truncateSync(filename, -5);
+    data = readDataSync(filename);
+    assertEquals(data.length, 0);
+    Deno.removeSync(filename);
+  }
+);
+
+unitTest(
+  { perms: { read: true, write: true } },
+  async function truncateSuccess(): Promise<void> {
+    const enc = new TextEncoder();
+    const d = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test_truncate.txt";
+    await Deno.writeFile(filename, d);
+    await Deno.truncate(filename, 20);
+    let data = await readData(filename);
+    assertEquals(data.length, 20);
+    await Deno.truncate(filename, 5);
+    data = await readData(filename);
+    assertEquals(data.length, 5);
+    await Deno.truncate(filename, -5);
+    data = await readData(filename);
+    assertEquals(data.length, 0);
+    await Deno.remove(filename);
+  }
+);
+
+unitTest({ perms: { write: false } }, function truncateSyncPerm(): void {
+  let err;
+  try {
+    Deno.mkdirSync("/test_truncateSyncPermission.txt");
+  } catch (e) {
+    err = e;
+  }
+  assert(err instanceof Deno.errors.PermissionDenied);
+  assertEquals(err.name, "PermissionDenied");
+});
+
+unitTest({ perms: { write: false } }, async function truncatePerm(): Promise<
+  void
+> {
+  let err;
+  try {
+    await Deno.mkdir("/test_truncatePermission.txt");
+  } catch (e) {
+    err = e;
+  }
+  assert(err instanceof Deno.errors.PermissionDenied);
+  assertEquals(err.name, "PermissionDenied");
+});