util: change util.inspect depth default

The current default is not ideal in most use cases. Therefore it is
changed to showing unlimited depth in case util.inspect is called
directly. The default is kept as before for console.log and similar.

Using console.dir will now show a depth of up to five and
console.assert / console.trace will show a unlimited depth.

PR-URL: nodejs#17907
Refs: nodejs#12693
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

Author: BridgeAR

doc/api/util.md

@@ -327,6 +327,9 @@ stream.write('With ES6');
 <!-- YAML
 added: v0.3.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/17907
+    description: The `depth` default changed to Infinity.
   - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/REPLACEME
     description: The `compact` option is supported now.
@@ -349,9 +352,6 @@ changes:
 * `options` {Object}
   * `showHidden` {boolean} If `true`, the `object`'s non-enumerable symbols and
     properties will be included in the formatted result. Defaults to `false`.
-  * `depth` {number} Specifies the number of times to recurse while formatting
-    the `object`. This is useful for inspecting large complicated objects.
-    Defaults to `2`. To make it recurse indefinitely pass `null`.
   * `colors` {boolean} If `true`, the output will be styled with ANSI color
     codes. Defaults to `false`. Colors are customizable, see
     [Customizing `util.inspect` colors][].
@@ -362,8 +362,8 @@ changes:
     objects. Defaults to `false`.
   * `maxArrayLength` {number} Specifies the maximum number of array and
     `TypedArray` elements to include when formatting. Defaults to `100`. Set to
-    `null` to show all array elements. Set to `0` or negative to show no array
-    elements.
+    `null` or `Infinity` to show all array elements. Set to `0` or negative to
+    show no array elements.
   * `breakLength` {number} The length at which an object's keys are split
     across multiple lines. Set to `Infinity` to format an object as a single
     line. Defaults to 60 for legacy compatibility.
@@ -374,6 +374,10 @@ changes:
     objects the same as arrays. Note that no text will be reduced below 16
     characters, no matter the `breakLength` size. For more information, see the
     example below. Defaults to `true`.
+  * `depth` {number} Specifies the number visible nested Objects in an `object`.
+    This is useful to minimize the inspection output for large complicated
+    objects. To make it recurse indefinitely pass `null` or `Infinity`. Defaults
+    to `Infinity`.
 
 The `util.inspect()` method returns a string representation of `object` that is
 intended for debugging. The output of `util.inspect` may change at any time
@@ -398,12 +402,23 @@ 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] }
 ```
 
 Values may supply their own custom `inspect(depth, opts)` functions, when
@@ -423,7 +438,7 @@ 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
 
@@ -437,7 +452,7 @@ 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/repl.js

@@ -103,8 +103,9 @@ 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 = internalModule.builtinLibs;
 

lib/util.js

@@ -64,7 +64,7 @@ const {
 
 const inspectDefaultOptions = Object.seal({
   showHidden: false,
-  depth: 2,
+  depth: null,
   colors: false,
   customInspect: true,
   showProxy: false,
@@ -317,8 +317,7 @@ Object.defineProperty(inspect, 'defaultOptions', {
     if (options === null || typeof options !== 'object') {
       throw new errors.TypeError('ERR_INVALID_ARG_TYPE', 'options', 'Object');
     }
-    Object.assign(inspectDefaultOptions, options);
-    return inspectDefaultOptions;
+    return _extend(inspectDefaultOptions, options);
   }
 });
 

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

@@ -3,6 +3,7 @@
 require('../common');
 const assert = require('assert');
 const BufferList = require('internal/streams/BufferList');
+const util = require('util');
 
 // Test empty buffer list.
 const emptyList = new BufferList();
@@ -25,3 +26,10 @@ assert.strictEqual(list.join(','), 'foo');
 const shifted = list.shift();
 assert.strictEqual(shifted, 'foo');
 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

@@ -48,13 +48,17 @@ 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

@@ -68,7 +68,7 @@ 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 } } } }');
@@ -106,7 +106,7 @@ 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(
@@ -1012,15 +1012,15 @@ 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.
@@ -1117,22 +1117,22 @@ 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)
   );
 
   // Set multiple options through object assignment
-  util.inspect.defaultOptions = { maxArrayLength: null, depth: null };
+  util.inspect.defaultOptions = { maxArrayLength: null, depth: 2 };
   assert(!/1 more item/.test(util.inspect(arr)));
-  assert(!/Object/.test(util.inspect(obj)));
+  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)