assert: move AssertionError into own file

This moves the `assert` parts from `internal/errors` into an own
file. `internal/errors` got bigger and bigger and it was difficult
to keep a good overview of what was going on. While doing so it
also removes the `internalAssert` function and just lazy loads
`assert`.

PR-URL: https://github.com/nodejs/node/pull/20486
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

5 files changed, 301 insertions, 306 deletions

diff --git a/lib/assert.js b/lib/assert.js
index ac9fd30793..27e71c2751 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -25,15 +25,12 @@ const {
   isDeepEqual,
   isDeepStrictEqual
 } = require('internal/util/comparisons');
-const {
-  AssertionError,
-  errorCache,
-  codes: {
-    ERR_AMBIGUOUS_ARGUMENT,
-    ERR_INVALID_ARG_TYPE,
-    ERR_INVALID_RETURN_VALUE
-  }
-} = require('internal/errors');
+const { codes: {
+  ERR_AMBIGUOUS_ARGUMENT,
+  ERR_INVALID_ARG_TYPE,
+  ERR_INVALID_RETURN_VALUE
+} } = require('internal/errors');
+const { AssertionError, errorCache } = require('internal/assert');
 const { openSync, closeSync, readSync } = require('fs');
 const { inspect, types: { isPromise, isRegExp } } = require('util');
 const { EOL } = require('os');
diff --git a/lib/internal/assert.js b/lib/internal/assert.js
new file mode 100644
index 0000000000..990065a937
--- /dev/null
+++ b/lib/internal/assert.js
@@ -0,0 +1,275 @@
+'use strict';
+
+const { inspect } = require('util');
+const { codes: {
+  ERR_INVALID_ARG_TYPE
+} } = require('internal/errors');
+
+let blue = '';
+let green = '';
+let red = '';
+let white = '';
+
+const READABLE_OPERATOR = {
+  deepStrictEqual: 'Input A expected to strictly deep-equal input B',
+  notDeepStrictEqual: 'Input A expected to strictly not deep-equal input B',
+  strictEqual: 'Input A expected to strictly equal input B',
+  notStrictEqual: 'Input A expected to strictly not equal input B'
+};
+
+function copyError(source) {
+  const keys = Object.keys(source);
+  const target = Object.create(Object.getPrototypeOf(source));
+  for (const key of keys) {
+    target[key] = source[key];
+  }
+  Object.defineProperty(target, 'message', { value: source.message });
+  return target;
+}
+
+function inspectValue(val) {
+  // The util.inspect default values could be changed. This makes sure the
+  // error messages contain the necessary information nevertheless.
+  return inspect(
+    val,
+    {
+      compact: false,
+      customInspect: false,
+      depth: 1000,
+      maxArrayLength: Infinity,
+      // Assert compares only enumerable properties (with a few exceptions).
+      showHidden: false,
+      // Having a long line as error is better than wrapping the line for
+      // comparison.
+      breakLength: Infinity,
+      // Assert does not detect proxies currently.
+      showProxy: false
+    }
+  ).split('\n');
+}
+
+function createErrDiff(actual, expected, operator) {
+  var other = '';
+  var res = '';
+  var lastPos = 0;
+  var end = '';
+  var skipped = false;
+  const actualLines = inspectValue(actual);
+  const expectedLines = inspectValue(expected);
+  const msg = READABLE_OPERATOR[operator] +
+        `:\n${green}+ expected${white} ${red}- actual${white}`;
+  const skippedMsg = ` ${blue}...${white} Lines skipped`;
+
+  // Remove all ending lines that match (this optimizes the output for
+  // readability by reducing the number of total changed lines).
+  var a = actualLines[actualLines.length - 1];
+  var b = expectedLines[expectedLines.length - 1];
+  var i = 0;
+  while (a === b) {
+    if (i++ < 2) {
+      end = `\n  ${a}${end}`;
+    } else {
+      other = a;
+    }
+    actualLines.pop();
+    expectedLines.pop();
+    if (actualLines.length === 0 || expectedLines.length === 0)
+      break;
+    a = actualLines[actualLines.length - 1];
+    b = expectedLines[expectedLines.length - 1];
+  }
+  if (i > 3) {
+    end = `\n${blue}...${white}${end}`;
+    skipped = true;
+  }
+  if (other !== '') {
+    end = `\n  ${other}${end}`;
+    other = '';
+  }
+
+  const maxLines = Math.max(actualLines.length, expectedLines.length);
+  var printedLines = 0;
+  var identical = 0;
+  for (i = 0; i < maxLines; i++) {
+    // Only extra expected lines exist
+    const cur = i - lastPos;
+    if (actualLines.length < i + 1) {
+      if (cur > 1 && i > 2) {
+        if (cur > 4) {
+          res += `\n${blue}...${white}`;
+          skipped = true;
+        } else if (cur > 3) {
+          res += `\n  ${expectedLines[i - 2]}`;
+          printedLines++;
+        }
+        res += `\n  ${expectedLines[i - 1]}`;
+        printedLines++;
+      }
+      lastPos = i;
+      other += `\n${green}+${white} ${expectedLines[i]}`;
+      printedLines++;
+    // Only extra actual lines exist
+    } else if (expectedLines.length < i + 1) {
+      if (cur > 1 && i > 2) {
+        if (cur > 4) {
+          res += `\n${blue}...${white}`;
+          skipped = true;
+        } else if (cur > 3) {
+          res += `\n  ${actualLines[i - 2]}`;
+          printedLines++;
+        }
+        res += `\n  ${actualLines[i - 1]}`;
+        printedLines++;
+      }
+      lastPos = i;
+      res += `\n${red}-${white} ${actualLines[i]}`;
+      printedLines++;
+    // Lines diverge
+    } else if (actualLines[i] !== expectedLines[i]) {
+      if (cur > 1 && i > 2) {
+        if (cur > 4) {
+          res += `\n${blue}...${white}`;
+          skipped = true;
+        } else if (cur > 3) {
+          res += `\n  ${actualLines[i - 2]}`;
+          printedLines++;
+        }
+        res += `\n  ${actualLines[i - 1]}`;
+        printedLines++;
+      }
+      lastPos = i;
+      res += `\n${red}-${white} ${actualLines[i]}`;
+      other += `\n${green}+${white} ${expectedLines[i]}`;
+      printedLines += 2;
+    // Lines are identical
+    } else {
+      res += other;
+      other = '';
+      if (cur === 1 || i === 0) {
+        res += `\n  ${actualLines[i]}`;
+        printedLines++;
+      }
+      identical++;
+    }
+    // Inspected object to big (Show ~20 rows max)
+    if (printedLines > 20 && i < maxLines - 2) {
+      return `${msg}${skippedMsg}\n${res}\n${blue}...${white}${other}\n` +
+        `${blue}...${white}`;
+    }
+  }
+
+  // Strict equal with identical objects that are not identical by reference.
+  if (identical === maxLines) {
+    // E.g., assert.deepStrictEqual(Symbol(), Symbol())
+    const base = operator === 'strictEqual' ?
+      'Input objects identical but not reference equal:' :
+      'Input objects not identical:';
+
+    // We have to get the result again. The lines were all removed before.
+    const actualLines = inspectValue(actual);
+
+    // Only remove lines in case it makes sense to collapse those.
+    // TODO: Accept env to always show the full error.
+    if (actualLines.length > 30) {
+      actualLines[26] = `${blue}...${white}`;
+      while (actualLines.length > 27) {
+        actualLines.pop();
+      }
+    }
+
+    return `${base}\n\n${actualLines.join('\n')}\n`;
+  }
+  return `${msg}${skipped ? skippedMsg : ''}\n${res}${other}${end}`;
+}
+
+class AssertionError extends Error {
+  constructor(options) {
+    if (typeof options !== 'object' || options === null) {
+      throw new ERR_INVALID_ARG_TYPE('options', 'Object', options);
+    }
+    var {
+      actual,
+      expected,
+      message,
+      operator,
+      stackStartFn
+    } = options;
+
+    if (message != null) {
+      super(message);
+    } else {
+      if (process.stdout.isTTY) {
+        // Reset on each call to make sure we handle dynamically set environment
+        // variables correct.
+        if (process.stdout.getColorDepth() !== 1) {
+          blue = '\u001b[34m';
+          green = '\u001b[32m';
+          white = '\u001b[39m';
+          red = '\u001b[31m';
+        } else {
+          blue = '';
+          green = '';
+          white = '';
+          red = '';
+        }
+      }
+      // Prevent the error stack from being visible by duplicating the error
+      // in a very close way to the original in case both sides are actually
+      // instances of Error.
+      if (typeof actual === 'object' && actual !== null &&
+          typeof expected === 'object' && expected !== null &&
+          'stack' in actual && actual instanceof Error &&
+          'stack' in expected && expected instanceof Error) {
+        actual = copyError(actual);
+        expected = copyError(expected);
+      }
+
+      if (operator === 'deepStrictEqual' || operator === 'strictEqual') {
+        super(createErrDiff(actual, expected, operator));
+      } else if (operator === 'notDeepStrictEqual' ||
+        operator === 'notStrictEqual') {
+        // In case the objects are equal but the operator requires unequal, show
+        // the first object and say A equals B
+        const res = inspectValue(actual);
+        const base = `Identical input passed to ${operator}:`;
+
+        // Only remove lines in case it makes sense to collapse those.
+        // TODO: Accept env to always show the full error.
+        if (res.length > 30) {
+          res[26] = `${blue}...${white}`;
+          while (res.length > 27) {
+            res.pop();
+          }
+        }
+
+        // Only print a single input.
+        if (res.length === 1) {
+          super(`${base} ${res[0]}`);
+        } else {
+          super(`${base}\n\n${res.join('\n')}\n`);
+        }
+      } else {
+        let res = inspect(actual);
+        let other = inspect(expected);
+        if (res.length > 128)
+          res = `${res.slice(0, 125)}...`;
+        if (other.length > 128)
+          other = `${other.slice(0, 125)}...`;
+        super(`${res} ${operator} ${other}`);
+      }
+    }
+
+    this.generatedMessage = !message;
+    this.name = 'AssertionError [ERR_ASSERTION]';
+    this.code = 'ERR_ASSERTION';
+    this.actual = actual;
+    this.expected = expected;
+    this.operator = operator;
+    Error.captureStackTrace(this, stackStartFn);
+  }
+}
+
+module.exports = {
+  AssertionError,
+  errorCache: new Map()
+};
diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index de4a566af4..6af266eaee 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -15,18 +15,6 @@ const kInfo = Symbol('info');
 const messages = new Map();
 const codes = {};
 
-let blue = '';
-let green = '';
-let red = '';
-let white = '';
-
-const READABLE_OPERATOR = {
-  deepStrictEqual: 'Input A expected to strictly deep-equal input B',
-  notDeepStrictEqual: 'Input A expected to strictly not deep-equal input B',
-  strictEqual: 'Input A expected to strictly equal input B',
-  notStrictEqual: 'Input A expected to strictly not equal input B'
-};
-
 const {
   errmap,
   UV_EAI_NODATA,
@@ -36,10 +24,10 @@ const { kMaxLength } = process.binding('buffer');
 const { defineProperty } = Object;
 
 // Lazily loaded
-var util;
-var buffer;
+let util;
+let assert;
 
-var internalUtil = null;
+let internalUtil = null;
 function lazyInternalUtil() {
   if (!internalUtil) {
     internalUtil = require('internal/util');
@@ -47,35 +35,11 @@ function lazyInternalUtil() {
   return internalUtil;
 }
 
-function copyError(source) {
-  const keys = Object.keys(source);
-  const target = Object.create(Object.getPrototypeOf(source));
-  for (const key of keys) {
-    target[key] = source[key];
-  }
-  Object.defineProperty(target, 'message', { value: source.message });
-  return target;
-}
-
-function inspectValue(val) {
-  // The util.inspect default values could be changed. This makes sure the
-  // error messages contain the necessary information nevertheless.
-  return util.inspect(
-    val,
-    {
-      compact: false,
-      customInspect: false,
-      depth: 1000,
-      maxArrayLength: Infinity,
-      // Assert compares only enumerable properties (with a few exceptions).
-      showHidden: false,
-      // Having a long line as error is better than wrapping the line for
-      // comparison.
-      breakLength: Infinity,
-      // Assert does not detect proxies currently.
-      showProxy: false
-    }
-  ).split('\n');
+let buffer;
+function lazyBuffer() {
+  if (buffer === undefined)
+    buffer = require('buffer').Buffer;
+  return buffer;
 }
 
 // A specialized Error that includes an additional info property with
@@ -240,254 +204,14 @@ function E(sym, val, def, ...otherClasses) {
   codes[sym] = def;
 }
 
-function lazyBuffer() {
-  if (buffer === undefined)
-    buffer = require('buffer').Buffer;
-  return buffer;
-}
-
-function createErrDiff(actual, expected, operator) {
-  var other = '';
-  var res = '';
-  var lastPos = 0;
-  var end = '';
-  var skipped = false;
-  if (util === undefined) util = require('util');
-  const actualLines = inspectValue(actual);
-  const expectedLines = inspectValue(expected);
-  const msg = READABLE_OPERATOR[operator] +
-        `:\n${green}+ expected${white} ${red}- actual${white}`;
-  const skippedMsg = ` ${blue}...${white} Lines skipped`;
-
-  // Remove all ending lines that match (this optimizes the output for
-  // readability by reducing the number of total changed lines).
-  var a = actualLines[actualLines.length - 1];
-  var b = expectedLines[expectedLines.length - 1];
-  var i = 0;
-  while (a === b) {
-    if (i++ < 2) {
-      end = `\n  ${a}${end}`;
-    } else {
-      other = a;
-    }
-    actualLines.pop();
-    expectedLines.pop();
-    if (actualLines.length === 0 || expectedLines.length === 0)
-      break;
-    a = actualLines[actualLines.length - 1];
-    b = expectedLines[expectedLines.length - 1];
-  }
-  if (i > 3) {
-    end = `\n${blue}...${white}${end}`;
-    skipped = true;
-  }
-  if (other !== '') {
-    end = `\n  ${other}${end}`;
-    other = '';
-  }
-
-  const maxLines = Math.max(actualLines.length, expectedLines.length);
-  var printedLines = 0;
-  var identical = 0;
-  for (i = 0; i < maxLines; i++) {
-    // Only extra expected lines exist
-    const cur = i - lastPos;
-    if (actualLines.length < i + 1) {
-      if (cur > 1 && i > 2) {
-        if (cur > 4) {
-          res += `\n${blue}...${white}`;
-          skipped = true;
-        } else if (cur > 3) {
-          res += `\n  ${expectedLines[i - 2]}`;
-          printedLines++;
-        }
-        res += `\n  ${expectedLines[i - 1]}`;
-        printedLines++;
-      }
-      lastPos = i;
-      other += `\n${green}+${white} ${expectedLines[i]}`;
-      printedLines++;
-    // Only extra actual lines exist
-    } else if (expectedLines.length < i + 1) {
-      if (cur > 1 && i > 2) {
-        if (cur > 4) {
-          res += `\n${blue}...${white}`;
-          skipped = true;
-        } else if (cur > 3) {
-          res += `\n  ${actualLines[i - 2]}`;
-          printedLines++;
-        }
-        res += `\n  ${actualLines[i - 1]}`;
-        printedLines++;
-      }
-      lastPos = i;
-      res += `\n${red}-${white} ${actualLines[i]}`;
-      printedLines++;
-    // Lines diverge
-    } else if (actualLines[i] !== expectedLines[i]) {
-      if (cur > 1 && i > 2) {
-        if (cur > 4) {
-          res += `\n${blue}...${white}`;
-          skipped = true;
-        } else if (cur > 3) {
-          res += `\n  ${actualLines[i - 2]}`;
-          printedLines++;
-        }
-        res += `\n  ${actualLines[i - 1]}`;
-        printedLines++;
-      }
-      lastPos = i;
-      res += `\n${red}-${white} ${actualLines[i]}`;
-      other += `\n${green}+${white} ${expectedLines[i]}`;
-      printedLines += 2;
-    // Lines are identical
-    } else {
-      res += other;
-      other = '';
-      if (cur === 1 || i === 0) {
-        res += `\n  ${actualLines[i]}`;
-        printedLines++;
-      }
-      identical++;
-    }
-    // Inspected object to big (Show ~20 rows max)
-    if (printedLines > 20 && i < maxLines - 2) {
-      return `${msg}${skippedMsg}\n${res}\n${blue}...${white}${other}\n` +
-        `${blue}...${white}`;
-    }
-  }
-
-  // Strict equal with identical objects that are not identical by reference.
-  if (identical === maxLines) {
-    // E.g., assert.deepStrictEqual(Symbol(), Symbol())
-    const base = operator === 'strictEqual' ?
-      'Input objects identical but not reference equal:' :
-      'Input objects not identical:';
-
-    // We have to get the result again. The lines were all removed before.
-    const actualLines = inspectValue(actual);
-
-    // Only remove lines in case it makes sense to collapse those.
-    // TODO: Accept env to always show the full error.
-    if (actualLines.length > 30) {
-      actualLines[26] = `${blue}...${white}`;
-      while (actualLines.length > 27) {
-        actualLines.pop();
-      }
-    }
-
-    return `${base}\n\n${actualLines.join('\n')}\n`;
-  }
-  return `${msg}${skipped ? skippedMsg : ''}\n${res}${other}${end}`;
-}
-
-class AssertionError extends Error {
-  constructor(options) {
-    if (typeof options !== 'object' || options === null) {
-      throw new codes.ERR_INVALID_ARG_TYPE('options', 'Object', options);
-    }
-    var {
-      actual,
-      expected,
-      message,
-      operator,
-      stackStartFn
-    } = options;
-
-    if (message != null) {
-      super(message);
-    } else {
-      if (process.stdout.isTTY) {
-        // Reset on each call to make sure we handle dynamically set environment
-        // variables correct.
-        if (process.stdout.getColorDepth() !== 1) {
-          blue = '\u001b[34m';
-          green = '\u001b[32m';
-          white = '\u001b[39m';
-          red = '\u001b[31m';
-        } else {
-          blue = '';
-          green = '';
-          white = '';
-          red = '';
-        }
-      }
-      if (util === undefined) util = require('util');
-      // Prevent the error stack from being visible by duplicating the error
-      // in a very close way to the original in case both sides are actually
-      // instances of Error.
-      if (typeof actual === 'object' && actual !== null &&
-          typeof expected === 'object' && expected !== null &&
-          'stack' in actual && actual instanceof Error &&
-          'stack' in expected && expected instanceof Error) {
-        actual = copyError(actual);
-        expected = copyError(expected);
-      }
-
-      if (operator === 'deepStrictEqual' || operator === 'strictEqual') {
-        super(createErrDiff(actual, expected, operator));
-      } else if (operator === 'notDeepStrictEqual' ||
-        operator === 'notStrictEqual') {
-        // In case the objects are equal but the operator requires unequal, show
-        // the first object and say A equals B
-        const res = inspectValue(actual);
-        const base = `Identical input passed to ${operator}:`;
-
-        // Only remove lines in case it makes sense to collapse those.
-        // TODO: Accept env to always show the full error.
-        if (res.length > 30) {
-          res[26] = `${blue}...${white}`;
-          while (res.length > 27) {
-            res.pop();
-          }
-        }
-
-        // Only print a single input.
-        if (res.length === 1) {
-          super(`${base} ${res[0]}`);
-        } else {
-          super(`${base}\n\n${res.join('\n')}\n`);
-        }
-      } else {
-        let res = util.inspect(actual);
-        let other = util.inspect(expected);
-        if (res.length > 128)
-          res = `${res.slice(0, 125)}...`;
-        if (other.length > 128)
-          other = `${other.slice(0, 125)}...`;
-        super(`${res} ${operator} ${other}`);
-      }
-    }
-
-    this.generatedMessage = !message;
-    this.name = 'AssertionError [ERR_ASSERTION]';
-    this.code = 'ERR_ASSERTION';
-    this.actual = actual;
-    this.expected = expected;
-    this.operator = operator;
-    Error.captureStackTrace(this, stackStartFn);
-  }
-}
-
-// This is defined here instead of using the assert module to avoid a
-// circular dependency. The effect is largely the same.
-function internalAssert(condition, message) {
-  if (!condition) {
-    throw new AssertionError({
-      message,
-      actual: false,
-      expected: true,
-      operator: '=='
-    });
-  }
-}
-
 function getMessage(key, args) {
   const msg = messages.get(key);
+
   if (util === undefined) util = require('util');
+  if (assert === undefined) assert = require('assert');
 
   if (typeof msg === 'function') {
-    internalAssert(
+    assert(
       msg.length <= args.length, // Default options do not count.
       `Code: ${key}; The provided arguments length (${args.length}) does not ` +
         `match the required ones (${msg.length}).`
@@ -496,7 +220,7 @@ function getMessage(key, args) {
   }
 
   const expectedLength = (msg.match(/%[dfijoOs]/g) || []).length;
-  internalAssert(
+  assert(
     expectedLength === args.length,
     `Code: ${key}; The provided arguments length (${args.length}) does not ` +
       `match the required ones (${expectedLength}).`
@@ -690,11 +414,9 @@ module.exports = {
   uvException,
   isStackOverflowError,
   getMessage,
-  AssertionError,
   SystemError,
   codes,
-  E, // This is exported only to facilitate testing.
-  errorCache: new Map() // This is in here only to facilitate testing.
+  E // This is exported only to facilitate testing.
 };
 
 // To declare an error message, use the E(sym, val, def) function above. The sym
@@ -1038,7 +760,7 @@ E('ERR_VM_MODULE_STATUS', 'Module status %s', Error);
 E('ERR_ZLIB_INITIALIZATION_FAILED', 'Initialization failed', Error);
 
 function invalidArgType(name, expected, actual) {
-  internalAssert(typeof name === 'string', 'name must be a string');
+  assert(typeof name === 'string', "'name' must be a string");
 
   // determiner: 'must be' or 'must not be'
   let determiner;
@@ -1064,7 +786,7 @@ function invalidArgType(name, expected, actual) {
 }
 
 function missingArgs(...args) {
-  internalAssert(args.length > 0, 'At least one arg needs to be specified');
+  assert(args.length > 0, 'At least one arg needs to be specified');
   let msg = 'The ';
   const len = args.length;
   args = args.map((a) => `"${a}"`);
@@ -1084,11 +806,11 @@ function missingArgs(...args) {
 }
 
 function oneOf(expected, thing) {
-  internalAssert(typeof thing === 'string', '`thing` has to be of type string');
+  assert(typeof thing === 'string', '`thing` has to be of type string');
   if (Array.isArray(expected)) {
     const len = expected.length;
-    internalAssert(len > 0,
-                   'At least one expected value needs to be specified');
+    assert(len > 0,
+           'At least one expected value needs to be specified');
     expected = expected.map((i) => String(i));
     if (len > 2) {
       return `one of ${thing} ${expected.slice(0, len - 1).join(', ')}, or ` +
diff --git a/node.gyp b/node.gyp
index aeb558d566..54f22a33da 100644
--- a/node.gyp
+++ b/node.gyp
@@ -79,6 +79,7 @@
       'lib/v8.js',
       'lib/vm.js',
       'lib/zlib.js',
+      'lib/internal/assert.js',
       'lib/internal/async_hooks.js',
       'lib/internal/buffer.js',
       'lib/internal/cli_table.js',
diff --git a/test/parallel/test-assert.js b/test/parallel/test-assert.js
index cbcda17ab7..cab6fb33e1 100644
--- a/test/parallel/test-assert.js
+++ b/test/parallel/test-assert.js
@@ -29,7 +29,7 @@ const common = require('../common');
 const assert = require('assert');
 const { EOL } = require('os');
 const EventEmitter = require('events');
-const { errorCache } = require('internal/errors');
+const { errorCache } = require('internal/assert');
 const { writeFileSync, unlinkSync } = require('fs');
 const { inspect } = require('util');
 const a = assert;