fix(runtime): lossy utf8 readTextFile (#14456)

1 files changed, 16 insertions, 0 deletions

diff --git a/cli/tests/unit/files_test.ts b/cli/tests/unit/files_test.ts
index a509672c0..d15f1f538 100644
--- a/cli/tests/unit/files_test.ts
+++ b/cli/tests/unit/files_test.ts
@@ -791,3 +791,19 @@ Deno.test(
     assertEquals(res, "hello world!");
   },
 );
+
+Deno.test(
+  { permissions: { read: true, write: true } },
+  async function readTextFileNonUtf8() {
+    const path = await Deno.makeTempFile();
+    const file = await Deno.open(path, { write: true });
+    await file.write(new TextEncoder().encode("hello "));
+    await file.write(new Uint8Array([0xC0]));
+    file.close();
+
+    const res = await Deno.readTextFile(path);
+    const resSync = Deno.readTextFileSync(path);
+    assertEquals(res, resSync);
+    assertEquals(res, "hello \uFFFD");
+  },
+);