1 files changed, 123 insertions, 0 deletions
diff --git a/tests/unit_node/_fs/_fs_ftruncate_test.ts b/tests/unit_node/_fs/_fs_ftruncate_test.ts
new file mode 100644
index 000000000..1e669fb60
--- /dev/null
+++ b/tests/unit_node/_fs/_fs_ftruncate_test.ts
@@ -0,0 +1,123 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+import { assertEquals, assertThrows, fail } from "@test_util/std/assert/mod.ts";
+import { ftruncate, ftruncateSync } from "node:fs";
+
+Deno.test({
+  name: "ASYNC: no callback function results in Error",
+  fn() {
+    assertThrows(
+      () => {
+        // @ts-expect-error Argument of type 'number' is not assignable to parameter of type 'NoParamCallback'
+        ftruncate(123, 0);
+      },
+      Error,
+      "No callback function supplied",
+    );
+  },
+});
+
+Deno.test({
+  name: "ASYNC: truncate entire file contents",
+  async fn() {
+    const filePath = Deno.makeTempFileSync();
+    await Deno.writeTextFile(filePath, "hello world");
+    using file = await Deno.open(filePath, {
+      read: true,
+      write: true,
+      create: true,
+    });
+
+    await new Promise<void>((resolve, reject) => {
+      ftruncate(file.rid, (err: Error | null) => {
+        if (err !== null) reject();
+        else resolve();
+      });
+    })
+      .then(
+        () => {
+          const fileInfo: Deno.FileInfo = Deno.lstatSync(filePath);
+          assertEquals(fileInfo.size, 0);
+        },
+        () => {
+          fail("No error expected");
+        },
+      )
+      .finally(() => {
+        Deno.removeSync(filePath);
+      });
+  },
+});
+
+Deno.test({
+  name: "ASYNC: truncate file to a size of precisely len bytes",
+  async fn() {
+    const filePath = Deno.makeTempFileSync();
+    await Deno.writeTextFile(filePath, "hello world");
+    using file = await Deno.open(filePath, {
+      read: true,
+      write: true,
+      create: true,
+    });
+
+    await new Promise<void>((resolve, reject) => {
+      ftruncate(file.rid, 3, (err: Error | null) => {
+        if (err !== null) reject();
+        else resolve();
+      });
+    })
+      .then(
+        () => {
+          const fileInfo: Deno.FileInfo = Deno.lstatSync(filePath);
+          assertEquals(fileInfo.size, 3);
+        },
+        () => {
+          fail("No error expected");
+        },
+      )
+      .finally(() => {
+        Deno.removeSync(filePath);
+      });
+  },
+});
+
+Deno.test({
+  name: "SYNC: truncate entire file contents",
+  fn() {
+    const filePath = Deno.makeTempFileSync();
+    Deno.writeFileSync(filePath, new TextEncoder().encode("hello world"));
+    using file = Deno.openSync(filePath, {
+      read: true,
+      write: true,
+      create: true,
+    });
+
+    try {
+      ftruncateSync(file.rid);
+      const fileInfo: Deno.FileInfo = Deno.lstatSync(filePath);
+      assertEquals(fileInfo.size, 0);
+    } finally {
+      Deno.removeSync(filePath);
+    }
+  },
+});
+
+Deno.test({
+  name: "SYNC: truncate file to a size of precisely len bytes",
+  fn() {
+    const filePath = Deno.makeTempFileSync();
+    Deno.writeFileSync(filePath, new TextEncoder().encode("hello world"));
+    using file = Deno.openSync(filePath, {
+      read: true,
+      write: true,
+      create: true,
+    });
+
+    try {
+      ftruncateSync(file.rid, 3);
+      const fileInfo: Deno.FileInfo = Deno.lstatSync(filePath);
+      assertEquals(fileInfo.size, 3);
+    } finally {
+      Deno.removeSync(filePath);
+    }
+  },
+});