util: change util.inspect depth default

The current default is not ideal in most use cases. Therefore it is
changed to inspect objects to a maximum depth of 20 in case
util.inspect is called with it's defaults. The default is kept at 2
when using console.log() and similar in the repl.

PR-URL: nodejs#17907
Refs: nodejs#12693

PR-URL: nodejs#22846
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

doc/api/util.md

@@ -360,6 +360,9 @@ stream.write('With ES6');
 <!-- YAML
 added: v0.3.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/22846
+    description: The `depth` default changed to `20`.
   - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/22788
     description: The `sorted` option is supported now.
@@ -401,7 +404,7 @@ changes:
   * `depth` {number} Specifies the number of times to recurse while formatting
     the `object`. This is useful for inspecting large complicated objects. To
     make it recurse up to the maximum call stack size pass `Infinity` or `null`.
-    **Default:** `2`.
+    **Default:** `20`.
   * `colors` {boolean} If `true`, the output will be styled with ANSI color
     codes. Colors are customizable, see [Customizing `util.inspect` colors][].
     **Default:** `false`.
@@ -458,12 +461,23 @@ util.inspect(new Bar()); // 'Bar {}'
 util.inspect(baz);       // '[foo] {}'
 ```
 
-The following example inspects all properties of the `util` object:
+The following example limits the inspected output of the `paths` property:
 
 ```js
 const util = require('util');
 
-console.log(util.inspect(util, { showHidden: true, depth: null }));
+console.log(util.inspect(module, { depth: 0 }));
+// Instead of showing all entries in `paths` `[Array]` is used to limit the
+// output for readability:
+
+// Module {
+//   id: '<repl>',
+//   exports: {},
+//   parent: undefined,
+//   filename: null,
+//   loaded: false,
+//   children: [],
+//   paths: [Array] }
 ```
 
 The following example highlights the difference with the `compact` option:
@@ -479,7 +493,7 @@ const o = {
     'foo']], 4],
   b: new Map([['za', 1], ['zb', 'test']])
 };
-console.log(util.inspect(o, { compact: true, depth: 5, breakLength: 80 }));
+console.log(util.inspect(o, { compact: true, breakLength: 80 }));
 
 // This will print
 
@@ -493,7 +507,7 @@ console.log(util.inspect(o, { compact: true, depth: 5, breakLength: 80 }));
 //   b: Map { 'za' => 1, 'zb' => 'test' } }
 
 // Setting `compact` to false changes the output to be more reader friendly.
-console.log(util.inspect(o, { compact: false, depth: 5, breakLength: 80 }));
+console.log(util.inspect(o, { compact: false, breakLength: 80 }));
 
 // {
 //   a: [

lib/internal/util/inspect.js

@@ -94,7 +94,7 @@ const hasOwnProperty = uncurryThis(Object.prototype.hasOwnProperty);
 
 const inspectDefaultOptions = Object.seal({
   showHidden: false,
-  depth: 2,
+  depth: 20,
   colors: false,
   customInspect: true,
   showProxy: false,

lib/repl.js

@@ -128,8 +128,9 @@ function hasOwnProperty(obj, prop) {
 // Can overridden with custom print functions, such as `probe` or `eyes.js`.
 // This is the default "writer" value if none is passed in the REPL options.
 const writer = exports.writer = (obj) => util.inspect(obj, writer.options);
-writer.options =
-    Object.assign({}, util.inspect.defaultOptions, { showProxy: true });
+writer.options = Object.assign({},
+                               util.inspect.defaultOptions,
+                               { showProxy: true, depth: 2 });
 
 exports._builtinLibs = builtinLibs;
 

test/parallel/test-stream-buffer-list.js

@@ -3,6 +3,7 @@
 require('../common');
 const assert = require('assert');
 const BufferList = require('internal/streams/buffer_list');
+const util = require('util');
 
 // Test empty buffer list.
 const emptyList = new BufferList();
@@ -30,3 +31,10 @@ assert.strictEqual(list.join(','), 'foo');
 const shifted = list.shift();
 assert.strictEqual(shifted, buf);
 assert.deepStrictEqual(list, new BufferList());
+
+const tmp = util.inspect.defaultOptions.colors;
+util.inspect.defaultOptions = { colors: true };
+assert.strictEqual(
+  util.inspect(list),
+  'BufferList { length: \u001b[33m0\u001b[39m }');
+util.inspect.defaultOptions = { colors: tmp };

test/parallel/test-util-inspect-proxy.js

@@ -50,13 +50,17 @@ const expected1 = 'Proxy [ {}, {} ]';
 const expected2 = 'Proxy [ Proxy [ {}, {} ], {} ]';
 const expected3 = 'Proxy [ Proxy [ Proxy [ {}, {} ], {} ], Proxy [ {}, {} ] ]';
 const expected4 = 'Proxy [ Proxy [ {}, {} ], Proxy [ Proxy [ {}, {} ], {} ] ]';
-const expected5 = 'Proxy [ Proxy [ Proxy [ Proxy [Array], {} ],' +
+const expected5 = 'Proxy [ Proxy [ Proxy [ Proxy [ {}, {} ], {} ],' +
                   ' Proxy [ {}, {} ] ],\n  Proxy [ Proxy [ {}, {} ]' +
-                  ', Proxy [ Proxy [Array], {} ] ] ]';
-const expected6 = 'Proxy [ Proxy [ Proxy [ Proxy [Array], Proxy [Array]' +
-                  ' ],\n    Proxy [ Proxy [Array], Proxy [Array] ] ],\n' +
-                  '  Proxy [ Proxy [ Proxy [Array], Proxy [Array] ],\n' +
-                  '    Proxy [ Proxy [Array], Proxy [Array] ] ] ]';
+                  ', Proxy [ Proxy [ {}, {} ], {} ] ] ]';
+const expected6 = 'Proxy [ Proxy [ Proxy [ Proxy [ Proxy [ {}, {} ], {} ], ' +
+                    'Proxy [ {}, {} ] ],\n' +
+                  '    Proxy [ Proxy [ {}, {} ], ' +
+                    'Proxy [ Proxy [ {}, {} ], {} ] ] ],\n' +
+                  '  Proxy [ Proxy [ Proxy [ Proxy [ {}, {} ], {} ], ' +
+                    'Proxy [ {}, {} ] ],\n' +
+                  '    Proxy [ Proxy [ {}, {} ], ' +
+                    'Proxy [ Proxy [ {}, {} ], {} ] ] ] ]';
 assert.strictEqual(
   util.inspect(proxy1, { showProxy: true, depth: null }),
   expected1);

test/parallel/test-util-inspect.js

@@ -71,7 +71,7 @@ assert.strictEqual(util.inspect({ a: 1, b: 2 }), '{ a: 1, b: 2 }');
 assert.strictEqual(util.inspect({ 'a': {} }), '{ a: {} }');
 assert.strictEqual(util.inspect({ 'a': { 'b': 2 } }), '{ a: { b: 2 } }');
 assert.strictEqual(util.inspect({ 'a': { 'b': { 'c': { 'd': 2 } } } }),
-                   '{ a: { b: { c: [Object] } } }');
+                   '{ a: { b: { c: { d: 2 } } } }');
 assert.strictEqual(
   util.inspect({ 'a': { 'b': { 'c': { 'd': 2 } } } }, false, null),
   '{ a: { b: { c: { d: 2 } } } }');
@@ -110,7 +110,7 @@ assert.strictEqual(util.inspect((new JSStream())._externalStream),
   assert.strictEqual(util.inspect({ a: regexp }, false, 0), '{ a: /regexp/ }');
 }
 
-assert(/Object/.test(
+assert(!/Object/.test(
   util.inspect({ a: { a: { a: { a: {} } } } }, undefined, undefined, true)
 ));
 assert(!/Object/.test(
@@ -1055,15 +1055,15 @@ if (typeof Symbol !== 'undefined') {
 // Empty and circular before depth.
 {
   const arr = [[[[]]]];
-  assert.strictEqual(util.inspect(arr), '[ [ [ [] ] ] ]');
+  assert.strictEqual(util.inspect(arr, { depth: 2 }), '[ [ [ [] ] ] ]');
   arr[0][0][0][0] = [];
-  assert.strictEqual(util.inspect(arr), '[ [ [ [Array] ] ] ]');
+  assert.strictEqual(util.inspect(arr, { depth: 2 }), '[ [ [ [Array] ] ] ]');
   arr[0][0][0] = {};
-  assert.strictEqual(util.inspect(arr), '[ [ [ {} ] ] ]');
+  assert.strictEqual(util.inspect(arr, { depth: 2 }), '[ [ [ {} ] ] ]');
   arr[0][0][0] = { a: 2 };
-  assert.strictEqual(util.inspect(arr), '[ [ [ [Object] ] ] ]');
+  assert.strictEqual(util.inspect(arr, { depth: 2 }), '[ [ [ [Object] ] ] ]');
   arr[0][0][0] = arr;
-  assert.strictEqual(util.inspect(arr), '[ [ [ [Circular] ] ] ]');
+  assert.strictEqual(util.inspect(arr, { depth: 2 }), '[ [ [ [Circular] ] ] ]');
 }
 
 // Corner cases.
@@ -1160,10 +1160,10 @@ if (typeof Symbol !== 'undefined') {
   assert(!/1 more item/.test(util.inspect(arr)));
   util.inspect.defaultOptions.maxArrayLength = oldOptions.maxArrayLength;
   assert(/1 more item/.test(util.inspect(arr)));
-  util.inspect.defaultOptions.depth = null;
-  assert(!/Object/.test(util.inspect(obj)));
-  util.inspect.defaultOptions.depth = oldOptions.depth;
+  util.inspect.defaultOptions.depth = 2;
   assert(/Object/.test(util.inspect(obj)));
+  util.inspect.defaultOptions.depth = oldOptions.depth;
+  assert(!/Object/.test(util.inspect(obj)));
   assert.strictEqual(
     JSON.stringify(util.inspect.defaultOptions),
     JSON.stringify(oldOptions)
@@ -1175,7 +1175,7 @@ if (typeof Symbol !== 'undefined') {
   assert(/Object/.test(util.inspect(obj)));
   util.inspect.defaultOptions = oldOptions;
   assert(/1 more item/.test(util.inspect(arr)));
-  assert(/Object/.test(util.inspect(obj)));
+  assert(!/Object/.test(util.inspect(obj)));
   assert.strictEqual(
     JSON.stringify(util.inspect.defaultOptions),
     JSON.stringify(oldOptions)
@@ -1561,11 +1561,19 @@ util.inspect(process);
   let head = list;
   // A linked list of length 100k should be inspectable in some way, even though
   // the real cutoff value is much lower than 100k.
-  for (let i = 0; i < 100000; i++)
+  for (let i = 0; i < 100000; i++) {
     head = head.next = {};
+  }
+
+  const res = Array(15)
+    .fill(0)
+    .map((_, i) => `{ next:\n${'   '.repeat(i + 1)}`)
+    .join('') +
+    '{ next: { next: { next: { next: { next: { next:' +
+    ' [Object] } } } } } } } } } } } } } } } } } } } } }';
   assert.strictEqual(
     util.inspect(list),
-    '{ next: { next: { next: [Object] } } }'
+    res
   );
   const longList = util.inspect(list, { depth: Infinity });
   const match = longList.match(/next/g);