util: do not reduce to a single line if not appropriate using inspect

This makes sure entries are not lined up on a single line if the
content contains any new line. That would otherwise cause confusing
output.

Signed-off-by: Ruben Bridgewater <ruben@bridgewater.de>

PR-URL: #41083
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/util/inspect.js

@@ -1931,8 +1931,11 @@ function reduceToSingleString(
         const start = output.length + ctx.indentationLvl +
                       braces[0].length + base.length + 10;
         if (isBelowBreakLength(ctx, output, start, base)) {
-          return `${base ? `${base} ` : ''}${braces[0]} ${join(output, ', ')}` +
-            ` ${braces[1]}`;
+          const joinedOutput = join(output, ', ');
+          if (!joinedOutput.includes('\n')) {
+            return `${base ? `${base} ` : ''}${braces[0]} ${joinedOutput}` +
+              ` ${braces[1]}`;
+          }
         }
       }
     }

test/parallel/test-util-inspect.js

@@ -2631,6 +2631,24 @@ assert.strictEqual(
 
   assert.strictEqual(out, expected);
 
+  // Array grouping should prevent lining up outer elements on a single line.
+  obj = [[[1, 2, 3, 4, 5, 6, 7, 8, 9]]];
+
+  out = util.inspect(obj, { compact: 3 });
+
+  expected = [
+    '[',
+    '  [',
+    '    [',
+    '      1, 2, 3, 4, 5,',
+    '      6, 7, 8, 9',
+    '    ]',
+    '  ]',
+    ']',
+  ].join('\n');
+
+  assert.strictEqual(out, expected);
+
   // Verify that array grouping and line consolidation does not happen together.
   obj = {
     a: {