test: improve fs coverage

PR-URL: #38517
Refs: https://coverage.nodejs.org/coverage-68e6673224365120/lib/fs.js.html#L330
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

test/parallel/test-fs-read.js

@@ -78,13 +78,21 @@ assert.throws(
   }
 );
 
-['buffer', 'offset', 'length'].forEach((option) =>
-  assert.throws(
-    () => fs.read(fd, {
-      [option]: null
-    }),
-    `not throws when options.${option} is null`
-  ));
+assert.throws(
+  () => fs.read(fd, { buffer: null }, common.mustNotCall()),
+  /TypeError: Cannot read property 'byteLength' of null/,
+  'throws when options.buffer is null'
+);
+
+assert.throws(
+  () => fs.readSync(fd, { buffer: null }),
+  {
+    name: 'TypeError',
+    message: 'The "buffer" argument must be an instance of Buffer, ' +
+    'TypedArray, or DataView. Received an instance of Object',
+  },
+  'throws when options.buffer is null'
+);
 
 assert.throws(
   () => fs.read(null, Buffer.alloc(1), 0, 1, 0),

test/parallel/test-fs-readfile.js

@@ -52,6 +52,23 @@ for (const e of fileInfo) {
     assert.deepStrictEqual(buf, e.contents);
   }));
 }
+// Test readFile size too large
+{
+  const kIoMaxLength = 2 ** 31 - 1;
+
+  const file = path.join(tmpdir.path, `${prefix}-too-large.txt`);
+  fs.writeFileSync(file, Buffer.from('0'));
+  fs.truncateSync(file, kIoMaxLength + 1);
+
+  fs.readFile(file, common.expectsError({
+    code: 'ERR_FS_FILE_TOO_LARGE',
+    name: 'RangeError',
+  }));
+  assert.throws(() => {
+    fs.readFileSync(file);
+  }, { code: 'ERR_FS_FILE_TOO_LARGE', name: 'RangeError' });
+}
+
 {
   // Test cancellation, before
   const signal = AbortSignal.abort();