util: remove custom inspection function

This removes the deprecated custom inspection function and fixes
all tests accordingly.

Refs: https://github.com/nodejs/node/issues/15549

PR-URL: https://github.com/nodejs/node/pull/20722
Refs: https://github.com/nodejs/node/issues/15549
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/deprecations.md

@@ -718,7 +718,7 @@ Type: Runtime
 <a id="DEP0079"></a>
 ### DEP0079: Custom inspection function on Objects via .inspect()
 
-Type: Runtime
+Type: End-of-Life
 
 Using a property named `inspect` on an object to specify a custom inspection
 function for [`util.inspect()`][] is deprecated. Use [`util.inspect.custom`][]

doc/api/util.md

@@ -393,8 +393,9 @@ changes:
   * `colors` {boolean} If `true`, the output will be styled with ANSI color
     codes. Colors are customizable, see [Customizing `util.inspect` colors][].
     **Default:** `false`.
-  * `customInspect` {boolean} If `false`, then custom `inspect(depth, opts)`
-    functions will not be called. **Default:** `true`.
+  * `customInspect` {boolean} If `false`, then
+    `[util.inspect.custom](depth, opts)` functions will not be called.
+    **Default:** `true`.
   * `showProxy` {boolean} If `true`, then objects and functions that are
     `Proxy` objects will be introspected to show their `target` and `handler`
     objects. **Default:** `false`.
@@ -416,7 +417,6 @@ 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. **Default:** `true`.
-
 * Returns: {string} The representation of passed object
 
 The `util.inspect()` method returns a string representation of `object` that is
@@ -450,10 +450,6 @@ const util = require('util');
 console.log(util.inspect(util, { showHidden: true, depth: null }));
 ```
 
-Values may supply their own custom `inspect(depth, opts)` functions, when
-called these receive the current `depth` in the recursive inspection, as well as
-the options object passed to `util.inspect()`.
-
 The following example highlights the difference with the `compact` option:
 
 ```js
@@ -568,9 +564,9 @@ terminals.
 
 <!-- type=misc -->
 
-Objects may also define their own `[util.inspect.custom](depth, opts)`
-(or the equivalent but deprecated `inspect(depth, opts)`) function that
-`util.inspect()` will invoke and use the result of when inspecting the object:
+Objects may also define their own `[util.inspect.custom](depth, opts)` function
+that `util.inspect()` will invoke and use the result of when inspecting the
+object:
 
 ```js
 const util = require('util');

lib/util.js

@@ -447,17 +447,7 @@ function formatValue(ctx, value, recurseTimes, ln) {
   // Provide a hook for user-specified inspect functions.
   // Check that value is an object with an inspect function on it
   if (ctx.customInspect) {
-    let maybeCustom = value[customInspectSymbol];
-
-    if (!maybeCustom && value.inspect !== exports.inspect &&
-        typeof value.inspect === 'function') {
-      maybeCustom = deprecate(
-        value.inspect,
-        'Custom inspection function on Objects via .inspect() is deprecated',
-        'DEP0079'
-      );
-    }
-
+    const maybeCustom = value[customInspectSymbol];
     if (typeof maybeCustom === 'function' &&
         // Filter out the util module, its inspect function is special
         maybeCustom !== exports.inspect &&

test/parallel/test-console.js

@@ -22,6 +22,7 @@
 'use strict';
 const common = require('../common');
 const assert = require('assert');
+const util = require('util');
 
 assert.ok(process.stdout.writable);
 assert.ok(process.stderr.writable);
@@ -46,8 +47,8 @@ assert.throws(() => console.timeEnd(Symbol('test')),
               TypeError);
 
 
-// an Object with a custom .inspect() function
-const custom_inspect = { foo: 'bar', inspect: () => 'inspect' };
+// An Object with a custom inspect function.
+const custom_inspect = { foo: 'bar', [util.inspect.custom]: () => 'inspect' };
 
 const strings = [];
 const errStrings = [];
@@ -192,9 +193,11 @@ for (const expected of expectedStrings) {
 }
 
 assert.strictEqual(strings.shift(),
-                   "{ foo: 'bar', inspect: [Function: inspect] }\n");
+                   "{ foo: 'bar',\n  [Symbol(util.inspect.custom)]: " +
+                    '[Function: [util.inspect.custom]] }\n');
 assert.strictEqual(strings.shift(),
-                   "{ foo: 'bar', inspect: [Function: inspect] }\n");
+                   "{ foo: 'bar',\n  [Symbol(util.inspect.custom)]: " +
+                    '[Function: [util.inspect.custom]] }\n');
 assert.ok(strings.shift().includes('foo: [Object]'));
 assert.strictEqual(strings.shift().includes('baz'), false);
 assert.strictEqual(strings.shift(), 'inspect inspect\n');

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

@@ -1,19 +0,0 @@
-'use strict';
-const common = require('../common');
-
-// Test that deprecation warning for custom inspection via the `.inspect()`
-// property (on the target object) is emitted once and only once.
-
-const util = require('util');
-
-{
-  const target = { inspect: () => 'Fhqwhgads' };
-  // `common.expectWarning` will expect the warning exactly one time only
-  common.expectWarning(
-    'DeprecationWarning',
-    'Custom inspection function on Objects via .inspect() is deprecated',
-    'DEP0079'
-  );
-  util.inspect(target);  // should emit deprecation warning
-  util.inspect(target);  // should not emit deprecation warning
-}

test/parallel/test-util-inspect.js

@@ -531,10 +531,10 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
   );
 }
 
-// GH-1941
+// https://github.com/nodejs/node-v0.x-archive/issues/1941
 assert.strictEqual(util.inspect(Object.create(Date.prototype)), 'Date {}');
 
-// GH-1944
+// https://github.com/nodejs/node-v0.x-archive/issues/1944
 {
   const d = new Date();
   d.toUTCString = null;
@@ -549,20 +549,20 @@ assert.strictEqual(util.inspect(Object.create(Date.prototype)), 'Date {}');
 }
 
 // Should not throw.
-const r = /regexp/;
-r.toString = null;
-util.inspect(r);
-
-// Bug with user-supplied inspect function returns non-string.
-util.inspect([{ inspect: () => 123 }]);
-
-// GH-2225
 {
-  const x = { inspect: util.inspect };
-  assert.strictEqual(util.inspect(x).includes('inspect'), true);
+  const r = /regexp/;
+  r.toString = null;
+  util.inspect(r);
 }
 
-// util.inspect should display the escaped value of a key.
+// See https://github.com/nodejs/node-v0.x-archive/issues/2225
+{
+  const x = { [util.inspect.custom]: util.inspect };
+  assert(util.inspect(x).includes(
+    '[Symbol(util.inspect.custom)]: \n   { [Function: inspect]'));
+}
+
+// `util.inspect` should display the escaped value of a key.
 {
   const w = {
     '\\': 1,
@@ -660,8 +660,8 @@ util.inspect({ hasOwnProperty: null });
 }
 
 {
-  // "customInspect" option can enable/disable calling inspect() on objects.
-  const subject = { inspect: () => 123 };
+  // "customInspect" option can enable/disable calling [util.inspect.custom]().
+  const subject = { [util.inspect.custom]: () => 123 };
 
   assert.strictEqual(
     util.inspect(subject, { customInspect: true }).includes('123'),
@@ -680,31 +680,6 @@ util.inspect({ hasOwnProperty: null });
     true
   );
 
-  // Custom inspect() functions should be able to return other Objects.
-  subject.inspect = () => ({ foo: 'bar' });
-
-  assert.strictEqual(util.inspect(subject), '{ foo: \'bar\' }');
-
-  subject.inspect = (depth, opts) => {
-    assert.strictEqual(opts.customInspectOptions, true);
-  };
-
-  util.inspect(subject, { customInspectOptions: true });
-}
-
-{
-  // "customInspect" option can enable/disable calling [util.inspect.custom]().
-  const subject = { [util.inspect.custom]: () => 123 };
-
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: true }).includes('123'),
-    true
-  );
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: false }).includes('123'),
-    false
-  );
-
   // A custom [util.inspect.custom]() should be able to return other Objects.
   subject[util.inspect.custom] = () => ({ foo: 'bar' });
 
@@ -717,43 +692,16 @@ util.inspect({ hasOwnProperty: null });
   util.inspect(subject, { customInspectOptions: true });
 }
 
-{
-  // [util.inspect.custom] takes precedence over inspect.
-  const subject = {
-    [util.inspect.custom]() { return 123; },
-    inspect() { return 456; }
-  };
-
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: true }).includes('123'),
-    true
-  );
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: false }).includes('123'),
-    false
-  );
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: true }).includes('456'),
-    false
-  );
-  assert.strictEqual(
-    util.inspect(subject, { customInspect: false }).includes('456'),
-    false
-  );
-}
-
 {
   // Returning `this` from a custom inspection function works.
-  assert.strictEqual(util.inspect({ a: 123, inspect() { return this; } }),
-                     '{ a: 123, inspect: [Function: inspect] }');
-
   const subject = { a: 123, [util.inspect.custom]() { return this; } };
   const UIC = 'util.inspect.custom';
   assert.strictEqual(util.inspect(subject),
                      `{ a: 123,\n  [Symbol(${UIC})]: [Function: [${UIC}]] }`);
 }
 
-// util.inspect with "colors" option should produce as many lines as without it.
+// Using `util.inspect` with "colors" option should produce as many lines as
+// without it.
 {
   function testLines(input) {
     const countLines = (str) => (str.match(/\n/g) || []).length;
@@ -1160,8 +1108,11 @@ util.inspect(process);
 
 // Setting custom inspect property to a non-function should do nothing.
 {
-  const obj = { inspect: 'fhqwhgads' };
-  assert.strictEqual(util.inspect(obj), "{ inspect: 'fhqwhgads' }");
+  const obj = { [util.inspect.custom]: 'fhqwhgads' };
+  assert.strictEqual(
+    util.inspect(obj),
+    "{ [Symbol(util.inspect.custom)]: 'fhqwhgads' }"
+  );
 }
 
 {