2 files changed, 31 insertions, 0 deletions
diff --git a/cli/tests/unit/write_file_test.ts b/cli/tests/unit/write_file_test.ts
index 9cbc0b272..945807b3f 100644
--- a/cli/tests/unit/write_file_test.ts
+++ b/cli/tests/unit/write_file_test.ts
@@ -98,6 +98,20 @@ Deno.test(
 
 Deno.test(
   { permissions: { read: true, write: true } },
+  function writeFileSyncCreateNew() {
+    const enc = new TextEncoder();
+    const data = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test.txt";
+    Deno.writeFileSync(filename, data, { createNew: true });
+
+    assertThrows(() => {
+      Deno.writeFileSync(filename, data, { createNew: true });
+    }, Deno.errors.AlreadyExists);
+  },
+);
+
+Deno.test(
+  { permissions: { read: true, write: true } },
   function writeFileSyncAppend() {
     const enc = new TextEncoder();
     const data = enc.encode("Hello");
@@ -218,6 +232,19 @@ Deno.test(
 
 Deno.test(
   { permissions: { read: true, write: true } },
+  async function writeFileCreateNew() {
+    const enc = new TextEncoder();
+    const data = enc.encode("Hello");
+    const filename = Deno.makeTempDirSync() + "/test.txt";
+    await Deno.writeFile(filename, data, { createNew: true });
+    await assertRejects(async () => {
+      await Deno.writeFile(filename, data, { createNew: true });
+    }, Deno.errors.AlreadyExists);
+  },
+);
+
+Deno.test(
+  { permissions: { read: true, write: true } },
   async function writeFileAppend() {
     const enc = new TextEncoder();
     const data = enc.encode("Hello");
diff --git a/cli/tsc/dts/lib.deno.ns.d.ts b/cli/tsc/dts/lib.deno.ns.d.ts
index 1049bf643..da4ec24ab 100644
--- a/cli/tsc/dts/lib.deno.ns.d.ts
+++ b/cli/tsc/dts/lib.deno.ns.d.ts
@@ -3296,6 +3296,10 @@ declare namespace Deno {
     /** Sets the option to allow creating a new file, if one doesn't already
      * exist at the specified path (defaults to `true`). */
     create?: boolean;
+    /** Defaults to `false`. If set to `true`, no file, directory, or symlink is
+     * allowed to exist at the target location. When createNew is set to `true`,
+     * `create` is ignored. */
+    createNew?: boolean;
     /** Permissions always applied to file. */
     mode?: number;
     /** An abort signal to allow cancellation of the file write operation.