util: honor breakLength: Infinity with deep objects in inspect

[RohithPariki]

Problem

When using util.inspect(obj, { breakLength: Infinity, depth: Infinity }) (or depth: null), deeply nested objects are unexpectedly split across multiple lines instead of being formatted on a single line. The Node.js documentation states:

breakLength <integer> The length at which input values are split across multiple lines. Set to Infinity to format the input as a single line (in combination with compact set to true or any number >= 1). Default: 80.

Root Cause

In reduceToSingleString() (lib/internal/util/inspect.js):

if (ctx.currentDepth - recurseTimes < ctx.compact &&
    entries === output.length) {

When inspecting an object with unlimited depth (depth: Infinity or depth: null), ctx.currentDepth increments as depth increases. Since compact defaults to 3, ctx.currentDepth - recurseTimes < ctx.compact fails for all parent/outer levels beyond depth 2. As a result, inline consolidation is skipped and newlines are inserted, despite breakLength: Infinity.

A previous closed attempt (#60783) disabled groupArrayElements when breakLength === Infinity, which broke compact array grouping with compact: 1.

Solution

In reduceToSingleString(), permit inline single-line consolidation when breakLength === Infinity and depth is unlimited (ctx.depth === null || ctx.depth === Infinity):

const isUnlimitedDepth = ctx.depth === null || ctx.depth === Infinity;
if (((ctx.breakLength === Infinity && isUnlimitedDepth) ||
     ctx.currentDepth - recurseTimes < ctx.compact) &&
    entries === output.length) {

This preserves array element grouping under compact: 1 and line wrapping for finite breakLength, while honoring the documented single-line contract for deep objects.

Testing

• Added regression tests in test/parallel/test-util-inspect.js covering breakLength: Infinity with depth: Infinity and depth: null for deeply nested objects.
• Validated compact array grouping (compact: 1), normal wrapping with finite breakLength, and default inspection behavior.

Fixes: #60475

[github-actions]

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[MikeMcC399]

The recommendations in:

• Guides and FAQs for first-time contributors

advise you should tackle only one issue at a time and that you should not open any new PRs until your first PR has been approved.

This is for your benefit and for the benefit of the team assisting with PRs. In both PRs the commit messages are incorrectly formatted, so it makes double the amount of work to advise you to correct the mistake in 2 different places.

You have later also opened #66472.

[MikeMcC399]

See Commit message guidelines according to the Pull requests documentation.

Please correct the problem with the text width.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.41%. Comparing base (7fab656) to head (6356053).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66471      +/-   ##
==========================================
- Coverage   90.42%   90.41%   -0.01%     
==========================================
  Files         791      791              
  Lines      275569   275571       +2     
  Branches    52842    52842              
==========================================
- Hits       249185   249161      -24     
- Misses      16802    16806       +4     
- Partials     9582     9604      +22     

Files with missing lines	Coverage Δ
lib/internal/util/inspect.js	97.04% <100.00%> (+<0.01%)	⬆️

... and 23 files with indirect coverage changes

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