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: nodejs#20486
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>

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');

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()
+};