assert: fix the string length check for printing the simple diff

PR-URL: https://github.com/nodejs/node/pull/55474
Reviewed-By: Pietro Marchini <pietro.marchini94@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/assert/assertion_error.js

@@ -134,7 +134,14 @@ function getStackedDiff(actual, expected) {
 }
 
 function getSimpleDiff(originalActual, actual, originalExpected, expected) {
-  const stringsLen = actual.length + expected.length;
+  let stringsLen = actual.length + expected.length;
+  // Accounting for the quotes wrapping strings
+  if (typeof originalActual === 'string') {
+    stringsLen -= 2;
+  }
+  if (typeof originalExpected === 'string') {
+    stringsLen -= 2;
+  }
   if (stringsLen <= kMaxShortStringLength && (originalActual !== 0 || originalExpected !== 0)) {
     return { message: `${actual} !== ${expected}`, header: '' };
   }

test/parallel/test-assert-deep.js

@@ -846,6 +846,26 @@ test('Additional tests', () => {
     }
   );
 
+  assert.throws(
+    () => assert.strictEqual('apple', 'pear'),
+    {
+      name: 'AssertionError',
+      message: 'Expected values to be strictly equal:\n\n\'apple\' !== \'pear\'\n'
+    }
+  );
+
+  assert.throws(
+    () => assert.strictEqual('ABABABABABAB', 'BABABABABABA'),
+    {
+      name: 'AssertionError',
+      message: 'Expected values to be strictly equal:\n' +
+        '+ actual - expected\n' +
+        '\n' +
+        "+ 'ABABABABABAB'\n" +
+        "- 'BABABABABABA'\n"
+    }
+  );
+
   assert.notDeepStrictEqual(new Date(), new Date(2000, 3, 14));
 
   assert.throws(

test/parallel/test-assert.js

@@ -919,11 +919,7 @@ test('Additional asserts', () => {
     {
       code: 'ERR_ASSERTION',
       constructor: assert.AssertionError,
-      message: 'Expected values to be strictly equal:\n' +
-        '+ actual - expected\n' +
-        '\n' +
-        "+ 'string'\n" +
-        '- false\n'
+      message: 'Expected values to be strictly equal:\n\n\'string\' !== false\n'
     }
   );
 
@@ -935,11 +931,7 @@ test('Additional asserts', () => {
     {
       code: 'ERR_ASSERTION',
       constructor: assert.AssertionError,
-      message: 'Expected values to be strictly equal:\n' +
-        '+ actual - expected\n' +
-        '\n' +
-        "+ 'string'\n" +
-        '- false\n'
+      message: 'Expected values to be strictly equal:\n\n\'string\' !== false\n'
     }
   );
 
@@ -951,11 +943,7 @@ test('Additional asserts', () => {
   }, {
     code: 'ERR_ASSERTION',
     constructor: assert.AssertionError,
-    message: 'Expected values to be strictly equal:\n' +
-      '+ actual - expected\n' +
-      '\n' +
-      "+ 'string'\n" +
-      '- false\n'
+    message: 'Expected values to be strictly equal:\n\n\'string\' !== false\n'
     }
   );
   /* eslint-enable @stylistic/js/indent */