trace_events: respect inspect() depth

This commit causes the Tracing class to account for
util.inspect() depth.

PR-URL: #28037
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: cjihrig

lib/trace_events.js

@@ -61,6 +61,9 @@ class Tracing {
   }
 
   [customInspectSymbol](depth, opts) {
+    if (typeof depth === 'number' && depth < 0)
+      return this;
+
     const obj = {
       enabled: this.enabled,
       categories: this.categories

test/parallel/test-util-inspect.js

@@ -2497,3 +2497,15 @@ assert.strictEqual(
     assert(i < 2 || line.startsWith('\u001b[90m'));
   });
 }
+
+{
+  // Tracing class respects inspect depth.
+  try {
+    const trace = require('trace_events').createTracing({ categories: ['fo'] });
+    const actual = util.inspect({ trace }, { depth: 0 });
+    assert.strictEqual(actual, '{ trace: [Tracing] }');
+  } catch (err) {
+    if (err.code !== 'ERR_TRACE_EVENTS_UNAVAILABLE')
+      throw err;
+  }
+}