util: honor breakLength Infinity when depth is Infinity

lib/internal/util/inspect.js

@@ -2022,7 +2022,14 @@ function formatError(err, constructor, tag, ctx, keys) {
   return stack;
 }
 
+function isUnlimitedDepth(ctx) {
+  return ctx.depth === null || ctx.depth === Infinity;
+}
+
 function groupArrayElements(ctx, output, value) {
+  if (!NumberIsFinite(ctx.breakLength) && isUnlimitedDepth(ctx)) {
+    return output;
+  }
   let totalLength = 0;
   let maxLength = 0;
   let i = 0;
@@ -2640,8 +2647,10 @@ function reduceToSingleString(
       // Consolidate all entries of the local most inner depth up to
       // `ctx.compact`, as long as the properties are smaller than
       // `ctx.breakLength`.
-      if (ctx.currentDepth - recurseTimes < ctx.compact &&
-          entries === output.length) {
+      const allowInline =
+        (!NumberIsFinite(ctx.breakLength) && isUnlimitedDepth(ctx)) ||
+        ctx.currentDepth - recurseTimes < ctx.compact;
+      if (allowInline && entries === output.length) {
         // Line up all entries on a single line in case the entries do not
         // exceed `breakLength`. Add 10 as constant to start next to all other
         // factors that may reduce `breakLength`.

test/parallel/test-util-inspect.js

@@ -589,6 +589,25 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
   }), "[ 'foo', <1 empty item>, ... 99 more items ]");
 }
 
+// `breakLength: Infinity` should force single-line output even if `depth` is
+// explicitly set to `Infinity`.
+{
+  const tree = {};
+  for (let i = 0; i < 5; i++) {
+    const branch = tree[`field${i}`] = { leaves: {} };
+    for (let j = 0; j < 5; j++) {
+      branch.leaves[`leaf${j}`] = new Array(10).fill(`value-${i}-${j}`);
+    }
+  }
+
+  const options = { breakLength: Infinity, compact: 3 };
+  const singleLine = util.inspect(tree, options);
+  assert.strictEqual(singleLine.includes('\n'), false);
+
+  const deepOptions = { ...options, depth: Infinity };
+  assert.strictEqual(util.inspect(tree, deepOptions).includes('\n'), false);
+}
+
 // Test for Array constructor in different context.
 {
   const map = new Map();