feat(std/node): Add AssertionError class (#7210)

std/node/_errors.ts

@@ -0,0 +1,48 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+// Adapted from Node.js. Copyright Joyent, Inc. and other Node contributors.
+
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// It will do so until we'll have Node errors completely ported (#5944):
+// Ref: https://github.com/nodejs/node/blob/50d28d4b3a616b04537feff014aa70437f064e30/lib/internal/errors.js#L251
+// Ref: https://github.com/nodejs/node/blob/50d28d4b3a616b04537feff014aa70437f064e30/lib/internal/errors.js#L299
+// Ref: https://github.com/nodejs/node/blob/50d28d4b3a616b04537feff014aa70437f064e30/lib/internal/errors.js#L325
+// Ref: https://github.com/nodejs/node/blob/50d28d4b3a616b04537feff014aa70437f064e30/lib/internal/errors.js#L943
+class ERR_INVALID_ARG_TYPE extends TypeError {
+  code = "ERR_INVALID_ARG_TYPE";
+
+  constructor(a1: string, a2: string, a3: unknown) {
+    super(
+      `The "${a1}" argument must be of type ${a2.toLocaleLowerCase()}. Received ${typeof a3} (${a3})`,
+    );
+    const { name } = this;
+    // Add the error code to the name to include it in the stack trace.
+    this.name = `${name} [${this.code}]`;
+    // Access the stack to generate the error message including the error code from the name.
+    this.stack;
+    // Reset the name to the actual name.
+    this.name = name;
+  }
+}
+
+export const codes = {
+  ERR_INVALID_ARG_TYPE,
+};

std/node/assert.ts

@@ -7,6 +7,8 @@ import {
   assertThrows,
 } from "../testing/asserts.ts";
 
+export { AssertionError } from "./assertion_error.ts";
+
 export {
   assert as default,
   assert as ok,

std/node/assert_test.ts

@@ -9,9 +9,9 @@ import {
   fail as denoFail,
 } from "../testing/asserts.ts";
 
-import assert from "./assert.ts";
+import AssertionError from "./assertion_error.ts";
 
-import {
+import assert, {
   ok,
   assert as assert_,
   deepStrictEqual,
@@ -21,6 +21,7 @@ import {
   match,
   throws,
   fail,
+  AssertionError as AssertionError_,
 } from "./assert.ts";
 
 Deno.test("API should be exposed", () => {
@@ -62,4 +63,9 @@ Deno.test("API should be exposed", () => {
     "`assertThrows()` should be exposed as `throws()`",
   );
   assertStrictEquals(fail, denoFail, "`fail()` should be exposed");
+  assertStrictEquals(
+    AssertionError,
+    AssertionError_,
+    "`AssertionError()` constructor should be exposed",
+  );
 });

std/node/assertion_error.ts

@@ -0,0 +1,577 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+// Adapted from Node.js. Copyright Joyent, Inc. and other Node contributors.
+
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// TODO(schwarzkopfb): change this when `Deno.consoleSize()` will be stable
+interface DenoUnstable {
+  consoleSize?(rid: number): { columns: number };
+}
+function getConsoleWidth(): number {
+  return (Deno as DenoUnstable).consoleSize?.(Deno.stderr.rid).columns ?? 80;
+}
+
+import { inspect } from "./util.ts";
+import { stripColor as removeColors } from "../fmt/colors.ts";
+
+// TODO(schwarzkopfb): we should implement Node's concept of "primordials"
+// Ref: https://github.com/denoland/deno/issues/6040#issuecomment-637305828
+const MathMax = Math.max;
+const { Error } = globalThis;
+const {
+  create: ObjectCreate,
+  defineProperty: ObjectDefineProperty,
+  getPrototypeOf: ObjectGetPrototypeOf,
+  getOwnPropertyDescriptor: ObjectGetOwnPropertyDescriptor,
+  keys: ObjectKeys,
+} = Object;
+
+import { codes } from "./_errors.ts";
+const { ERR_INVALID_ARG_TYPE } = codes;
+
+let blue = "";
+let green = "";
+let red = "";
+let defaultColor = "";
+
+const kReadableOperator: { [key: string]: string } = {
+  deepStrictEqual: "Expected values to be strictly deep-equal:",
+  strictEqual: "Expected values to be strictly equal:",
+  strictEqualObject: 'Expected "actual" to be reference-equal to "expected":',
+  deepEqual: "Expected values to be loosely deep-equal:",
+  notDeepStrictEqual: 'Expected "actual" not to be strictly deep-equal to:',
+  notStrictEqual: 'Expected "actual" to be strictly unequal to:',
+  notStrictEqualObject:
+    'Expected "actual" not to be reference-equal to "expected":',
+  notDeepEqual: 'Expected "actual" not to be loosely deep-equal to:',
+  notIdentical: "Values have same structure but are not reference-equal:",
+  notDeepEqualUnequal: "Expected values not to be loosely deep-equal:",
+};
+
+// Comparing short primitives should just show === / !== instead of using the
+// diff.
+const kMaxShortLength = 12;
+
+export function copyError(source: Error): Error {
+  const keys = ObjectKeys(source);
+  const target = ObjectCreate(ObjectGetPrototypeOf(source));
+  for (const key of keys) {
+    const desc = ObjectGetOwnPropertyDescriptor(source, key);
+
+    if (desc !== undefined) {
+      ObjectDefineProperty(target, key, desc);
+    }
+  }
+  ObjectDefineProperty(target, "message", { value: source.message });
+  return target;
+}
+
+export function inspectValue(val: unknown): string {
+  // 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,
+      // Assert does not detect proxies currently.
+      showProxy: false,
+      sorted: true,
+      // Inspect getters as we also check them when comparing entries.
+      getters: true,
+    },
+  );
+}
+
+export function createErrDiff(
+  actual: unknown,
+  expected: unknown,
+  operator: string,
+): string {
+  let other = "";
+  let res = "";
+  let end = "";
+  let skipped = false;
+  const actualInspected = inspectValue(actual);
+  const actualLines = actualInspected.split("\n");
+  const expectedLines = inspectValue(expected).split("\n");
+
+  let i = 0;
+  let indicator = "";
+
+  // In case both values are objects or functions explicitly mark them as not
+  // reference equal for the `strictEqual` operator.
+  if (
+    operator === "strictEqual" &&
+    ((typeof actual === "object" && actual !== null &&
+      typeof expected === "object" && expected !== null) ||
+      (typeof actual === "function" && typeof expected === "function"))
+  ) {
+    operator = "strictEqualObject";
+  }
+
+  // If "actual" and "expected" fit on a single line and they are not strictly
+  // equal, check further special handling.
+  if (
+    actualLines.length === 1 && expectedLines.length === 1 &&
+    actualLines[0] !== expectedLines[0]
+  ) {
+    // Check for the visible length using the `removeColors()` function, if
+    // appropriate.
+    const c = inspect.defaultOptions.colors;
+    const actualRaw = c ? removeColors(actualLines[0]) : actualLines[0];
+    const expectedRaw = c ? removeColors(expectedLines[0]) : expectedLines[0];
+    const inputLength = actualRaw.length + expectedRaw.length;
+    // If the character length of "actual" and "expected" together is less than
+    // kMaxShortLength and if neither is an object and at least one of them is
+    // not `zero`, use the strict equal comparison to visualize the output.
+    if (inputLength <= kMaxShortLength) {
+      if (
+        (typeof actual !== "object" || actual === null) &&
+        (typeof expected !== "object" || expected === null) &&
+        (actual !== 0 || expected !== 0)
+      ) { // -0 === +0
+        return `${kReadableOperator[operator]}\n\n` +
+          `${actualLines[0]} !== ${expectedLines[0]}\n`;
+      }
+    } else if (operator !== "strictEqualObject") {
+      // If the stderr is a tty and the input length is lower than the current
+      // columns per line, add a mismatch indicator below the output. If it is
+      // not a tty, use a default value of 80 characters.
+      const maxLength = Deno.isatty(Deno.stderr.rid) ? getConsoleWidth() : 80;
+      if (inputLength < maxLength) {
+        while (actualRaw[i] === expectedRaw[i]) {
+          i++;
+        }
+        // Ignore the first characters.
+        if (i > 2) {
+          // Add position indicator for the first mismatch in case it is a
+          // single line and the input length is less than the column length.
+          indicator = `\n  ${" ".repeat(i)}^`;
+          i = 0;
+        }
+      }
+    }
+  }
+
+  // Remove all ending lines that match (this optimizes the output for
+  // readability by reducing the number of total changed lines).
+  let a = actualLines[actualLines.length - 1];
+  let b = expectedLines[expectedLines.length - 1];
+  while (a === b) {
+    if (i++ < 3) {
+      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];
+  }
+
+  const maxLines = MathMax(actualLines.length, expectedLines.length);
+  // Strict equal with identical objects that are not identical by reference.
+  // E.g., assert.deepStrictEqual({ a: Symbol() }, { a: Symbol() })
+  if (maxLines === 0) {
+    // We have to get the result again. The lines were all removed before.
+    const actualLines = actualInspected.split("\n");
+
+    // Only remove lines in case it makes sense to collapse those.
+    if (actualLines.length > 50) {
+      actualLines[46] = `${blue}...${defaultColor}`;
+      while (actualLines.length > 47) {
+        actualLines.pop();
+      }
+    }
+
+    return `${kReadableOperator.notIdentical}\n\n${actualLines.join("\n")}\n`;
+  }
+
+  // There were at least five identical lines at the end. Mark a couple of
+  // skipped.
+  if (i >= 5) {
+    end = `\n${blue}...${defaultColor}${end}`;
+    skipped = true;
+  }
+  if (other !== "") {
+    end = `\n  ${other}${end}`;
+    other = "";
+  }
+
+  let printedLines = 0;
+  let identical = 0;
+  const msg = kReadableOperator[operator] +
+    `\n${green}+ actual${defaultColor} ${red}- expected${defaultColor}`;
+  const skippedMsg = ` ${blue}...${defaultColor} Lines skipped`;
+
+  let lines = actualLines;
+  let plusMinus = `${green}+${defaultColor}`;
+  let maxLength = expectedLines.length;
+  if (actualLines.length < maxLines) {
+    lines = expectedLines;
+    plusMinus = `${red}-${defaultColor}`;
+    maxLength = actualLines.length;
+  }
+
+  for (i = 0; i < maxLines; i++) {
+    if (maxLength < i + 1) {
+      // If more than two former lines are identical, print them. Collapse them
+      // in case more than five lines were identical.
+      if (identical > 2) {
+        if (identical > 3) {
+          if (identical > 4) {
+            if (identical === 5) {
+              res += `\n  ${lines[i - 3]}`;
+              printedLines++;
+            } else {
+              res += `\n${blue}...${defaultColor}`;
+              skipped = true;
+            }
+          }
+          res += `\n  ${lines[i - 2]}`;
+          printedLines++;
+        }
+        res += `\n  ${lines[i - 1]}`;
+        printedLines++;
+      }
+      // No identical lines before.
+      identical = 0;
+      // Add the expected line to the cache.
+      if (lines === actualLines) {
+        res += `\n${plusMinus} ${lines[i]}`;
+      } else {
+        other += `\n${plusMinus} ${lines[i]}`;
+      }
+      printedLines++;
+      // Only extra actual lines exist
+      // Lines diverge
+    } else {
+      const expectedLine = expectedLines[i];
+      let actualLine = actualLines[i];
+      // If the lines diverge, specifically check for lines that only diverge by
+      // a trailing comma. In that case it is actually identical and we should
+      // mark it as such.
+      let divergingLines = actualLine !== expectedLine &&
+        (!actualLine.endsWith(",") ||
+          actualLine.slice(0, -1) !== expectedLine);
+      // If the expected line has a trailing comma but is otherwise identical,
+      // add a comma at the end of the actual line. Otherwise the output could
+      // look weird as in:
+      //
+      //   [
+      //     1         // No comma at the end!
+      // +   2
+      //   ]
+      //
+      if (
+        divergingLines &&
+        expectedLine.endsWith(",") &&
+        expectedLine.slice(0, -1) === actualLine
+      ) {
+        divergingLines = false;
+        actualLine += ",";
+      }
+      if (divergingLines) {
+        // If more than two former lines are identical, print them. Collapse
+        // them in case more than five lines were identical.
+        if (identical > 2) {
+          if (identical > 3) {
+            if (identical > 4) {
+              if (identical === 5) {
+                res += `\n  ${actualLines[i - 3]}`;
+                printedLines++;
+              } else {
+                res += `\n${blue}...${defaultColor}`;
+                skipped = true;
+              }
+            }
+            res += `\n  ${actualLines[i - 2]}`;
+            printedLines++;
+          }
+          res += `\n  ${actualLines[i - 1]}`;
+          printedLines++;
+        }
+        // No identical lines before.
+        identical = 0;
+        // Add the actual line to the result and cache the expected diverging
+        // line so consecutive diverging lines show up as +++--- and not +-+-+-.
+        res += `\n${green}+${defaultColor} ${actualLine}`;
+        other += `\n${red}-${defaultColor} ${expectedLine}`;
+        printedLines += 2;
+        // Lines are identical
+      } else {
+        // Add all cached information to the result before adding other things
+        // and reset the cache.
+        res += other;
+        other = "";
+        identical++;
+        // The very first identical line since the last diverging line is be
+        // added to the result.
+        if (identical <= 2) {
+          res += `\n  ${actualLine}`;
+          printedLines++;
+        }
+      }
+    }
+    // Inspected object to big (Show ~50 rows max)
+    if (printedLines > 50 && i < maxLines - 2) {
+      return `${msg}${skippedMsg}\n${res}\n${blue}...${defaultColor}${other}\n` +
+        `${blue}...${defaultColor}`;
+    }
+  }
+
+  return `${msg}${skipped ? skippedMsg : ""}\n${res}${other}${end}${indicator}`;
+}
+
+export interface AssertionErrorDetailsDescriptor {
+  message: string;
+  actual: unknown;
+  expected: unknown;
+  operator: string;
+  stack: Error;
+}
+
+export interface AssertionErrorConstructorOptions {
+  message?: string;
+  actual?: unknown;
+  expected?: unknown;
+  operator?: string;
+  details?: AssertionErrorDetailsDescriptor[];
+  // eslint-disable-next-line @typescript-eslint/ban-types
+  stackStartFn?: Function;
+  // Compatibility with older versions.
+  // eslint-disable-next-line @typescript-eslint/ban-types
+  stackStartFunction?: Function;
+}
+
+interface ErrorWithStackTraceLimit extends ErrorConstructor {
+  stackTraceLimit: number;
+}
+
+export class AssertionError extends Error {
+  [key: string]: unknown
+
+  // deno-lint-ignore constructor-super
+  constructor(options: AssertionErrorConstructorOptions) {
+    if (typeof options !== "object" || options === null) {
+      throw new ERR_INVALID_ARG_TYPE("options", "Object", options);
+    }
+    const {
+      message,
+      operator,
+      stackStartFn,
+      details,
+      // Compatibility with older versions.
+      stackStartFunction,
+    } = options;
+    let {
+      actual,
+      expected,
+    } = options;
+
+    // TODO(schwarzkopfb): `stackTraceLimit` should be added to `ErrorConstructor` in
+    // cli/dts/lib.deno.shared_globals.d.ts
+    const limit = (Error as ErrorWithStackTraceLimit).stackTraceLimit;
+    (Error as ErrorWithStackTraceLimit).stackTraceLimit = 0;
+
+    if (message != null) {
+      super(String(message));
+    } else {
+      if (Deno.isatty(Deno.stderr.rid)) {
+        // Reset on each call to make sure we handle dynamically set environment
+        // variables correct.
+        if (Deno.noColor) {
+          blue = "";
+          green = "";
+          defaultColor = "";
+          red = "";
+        } else {
+          blue = "\u001b[34m";
+          green = "\u001b[32m";
+          defaultColor = "\u001b[39m";
+          red = "\u001b[31m";
+        }
+      }
+      // 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
+        let base = kReadableOperator[operator];
+        const res = inspectValue(actual).split("\n");
+
+        // In case "actual" is an object or a function, it should not be
+        // reference equal.
+        if (
+          operator === "notStrictEqual" &&
+          ((typeof actual === "object" && actual !== null) ||
+            typeof actual === "function")
+        ) {
+          base = kReadableOperator.notStrictEqualObject;
+        }
+
+        // Only remove lines in case it makes sense to collapse those.
+        if (res.length > 50) {
+          res[46] = `${blue}...${defaultColor}`;
+          while (res.length > 47) {
+            res.pop();
+          }
+        }
+
+        // Only print a single input.
+        if (res.length === 1) {
+          super(`${base}${res[0].length > 5 ? "\n\n" : " "}${res[0]}`);
+        } else {
+          super(`${base}\n\n${res.join("\n")}\n`);
+        }
+      } else {
+        let res = inspectValue(actual);
+        let other = inspectValue(expected);
+        const knownOperator = kReadableOperator[operator ?? ""];
+        if (operator === "notDeepEqual" && res === other) {
+          res = `${knownOperator}\n\n${res}`;
+          if (res.length > 1024) {
+            res = `${res.slice(0, 1021)}...`;
+          }
+          super(res);
+        } else {
+          if (res.length > 512) {
+            res = `${res.slice(0, 509)}...`;
+          }
+          if (other.length > 512) {
+            other = `${other.slice(0, 509)}...`;
+          }
+          if (operator === "deepEqual") {
+            res = `${knownOperator}\n\n${res}\n\nshould loosely deep-equal\n\n`;
+          } else {
+            const newOp = kReadableOperator[`${operator}Unequal`];
+            if (newOp) {
+              res = `${newOp}\n\n${res}\n\nshould not loosely deep-equal\n\n`;
+            } else {
+              other = ` ${operator} ${other}`;
+            }
+          }
+          super(`${res}${other}`);
+        }
+      }
+    }
+
+    (Error as ErrorWithStackTraceLimit).stackTraceLimit = limit;
+
+    this.generatedMessage = !message;
+    ObjectDefineProperty(this, "name", {
+      value: "AssertionError [ERR_ASSERTION]",
+      enumerable: false,
+      writable: true,
+      configurable: true,
+    });
+    this.code = "ERR_ASSERTION";
+
+    if (details) {
+      this.actual = undefined;
+      this.expected = undefined;
+      this.operator = undefined;
+
+      for (let i = 0; i < details.length; i++) {
+        this["message " + i] = details[i].message;
+        this["actual " + i] = details[i].actual;
+        this["expected " + i] = details[i].expected;
+        this["operator " + i] = details[i].operator;
+        this["stack trace " + i] = details[i].stack;
+      }
+    } else {
+      this.actual = actual;
+      this.expected = expected;
+      this.operator = operator;
+    }
+
+    Error.captureStackTrace(this, stackStartFn || stackStartFunction);
+    // Create error message including the error code in the name.
+    this.stack;
+    // Reset the name.
+    this.name = "AssertionError";
+  }
+
+  toString() {
+    return `${this.name} [${this.code}]: ${this.message}`;
+  }
+
+  [inspect.custom](recurseTimes: number, ctx: Record<string, unknown>) {
+    // Long strings should not be fully inspected.
+    const tmpActual = this.actual;
+    const tmpExpected = this.expected;
+
+    for (const name of ["actual", "expected"]) {
+      if (typeof this[name] === "string") {
+        const value = (this[name] as string);
+        const lines = value.split("\n");
+        if (lines.length > 10) {
+          lines.length = 10;
+          this[name] = `${lines.join("\n")}\n...`;
+        } else if (value.length > 512) {
+          this[name] = `${value.slice(512)}...`;
+        }
+      }
+    }
+
+    // This limits the `actual` and `expected` property default inspection to
+    // the minimum depth. Otherwise those values would be too verbose compared
+    // to the actual error message which contains a combined view of these two
+    // input values.
+    const result = inspect(this, {
+      ...ctx,
+      customInspect: false,
+      depth: 0,
+    });
+
+    // Reset the properties after inspection.
+    this.actual = tmpActual;
+    this.expected = tmpExpected;
+
+    return result;
+  }
+}
+
+export default AssertionError;

std/node/assertion_error_test.ts

@@ -0,0 +1,175 @@
+import { stripColor } from "../fmt/colors.ts";
+import {
+  assert,
+  assertEquals,
+  assertNotStrictEquals,
+  assertStrictEquals,
+} from "../testing/asserts.ts";
+import {
+  AssertionError,
+  copyError,
+  inspectValue,
+  createErrDiff,
+} from "./assertion_error.ts";
+
+Deno.test({
+  name: "copyError()",
+  fn() {
+    class TestError extends Error {}
+    const err = new TestError("this is a test");
+    const copy = copyError(err);
+
+    assert(copy instanceof Error, "Copy should inherit from Error.");
+    assert(copy instanceof TestError, "Copy should inherit from TestError.");
+    assertEquals(copy, err, "Copy should be equal to the original error.");
+    assertNotStrictEquals(
+      copy,
+      err,
+      "Copy should not be strictly equal to the original error.",
+    );
+  },
+});
+
+Deno.test({
+  name: "inspectValue()",
+  fn() {
+    const obj = { a: 1, b: [2] };
+    Object.defineProperty(obj, "c", { value: 3, enumerable: false });
+    assertStrictEquals(
+      stripColor(inspectValue(obj)),
+      "{ a: 1, b: [ 2 ] }",
+    );
+  },
+});
+
+Deno.test({
+  name: "createErrDiff()",
+  fn() {
+    assertStrictEquals(
+      stripColor(
+        createErrDiff({ a: 1, b: 2 }, { a: 2, b: 2 }, "strictEqual"),
+      ),
+      stripColor(
+        'Expected "actual" to be reference-equal to "expected":' + "\n" +
+          "+ actual - expected" + "\n" +
+          "\n" +
+          "+ { a: 1, b: 2 }" + "\n" +
+          "- { a: 2, b: 2 }",
+      ),
+    );
+  },
+});
+
+Deno.test({
+  name: "construct AssertionError() with given message",
+  fn() {
+    const err = new AssertionError(
+      {
+        message: "answer",
+        actual: "42",
+        expected: "42",
+        operator: "notStrictEqual",
+      },
+    );
+    assertStrictEquals(err.name, "AssertionError");
+    assertStrictEquals(err.message, "answer");
+    assertStrictEquals(err.generatedMessage, false);
+    assertStrictEquals(err.code, "ERR_ASSERTION");
+    assertStrictEquals(err.actual, "42");
+    assertStrictEquals(err.expected, "42");
+    assertStrictEquals(err.operator, "notStrictEqual");
+  },
+});
+
+Deno.test({
+  name: "construct AssertionError() with generated message",
+  fn() {
+    const err = new AssertionError(
+      { actual: 1, expected: 2, operator: "equal" },
+    );
+    assertStrictEquals(err.name, "AssertionError");
+    assertStrictEquals(stripColor(err.message), "1 equal 2");
+    assertStrictEquals(err.generatedMessage, true);
+    assertStrictEquals(err.code, "ERR_ASSERTION");
+    assertStrictEquals(err.actual, 1);
+    assertStrictEquals(err.expected, 2);
+    assertStrictEquals(err.operator, "equal");
+  },
+});
+
+Deno.test({
+  name: "construct AssertionError() with stackStartFn",
+  fn: function stackStartFn() {
+    const expected = /node/;
+    const err = new AssertionError({
+      actual: "deno",
+      expected,
+      operator: "match",
+      stackStartFn,
+    });
+    assertStrictEquals(err.name, "AssertionError");
+    assertStrictEquals(stripColor(err.message), "deno match /node/");
+    assertStrictEquals(err.generatedMessage, true);
+    assertStrictEquals(err.code, "ERR_ASSERTION");
+    assertStrictEquals(err.actual, "deno");
+    assertStrictEquals(err.expected, expected);
+    assertStrictEquals(err.operator, "match");
+    assert(err.stack, "error should have a stack");
+    assert(
+      !err.stack?.includes("stackStartFn"),
+      "stackStartFn() should not present in stack trace",
+    );
+  },
+});
+
+Deno.test({
+  name: "error details",
+  fn() {
+    const stack0 = new Error();
+    const stack1 = new Error();
+    const err = new AssertionError({
+      message: "Function(s) were not called the expected number of times",
+      details: [
+        {
+          message:
+            "Expected the calls function to be executed 2 time(s) but was executed 3 time(s).",
+          actual: 3,
+          expected: 2,
+          operator: "calls",
+          stack: stack0,
+        },
+        {
+          message:
+            "Expected the fn function to be executed 1 time(s) but was executed 0 time(s).",
+          actual: 0,
+          expected: 1,
+          operator: "fn",
+          stack: stack1,
+        },
+      ],
+    });
+
+    assertStrictEquals(
+      err.message,
+      "Function(s) were not called the expected number of times",
+    );
+
+    assertStrictEquals(
+      err["message 0"],
+      "Expected the calls function to be executed 2 time(s) but was executed 3 time(s).",
+    );
+    assertStrictEquals(err["actual 0"], 3);
+    assertStrictEquals(err["expected 0"], 2);
+    assertStrictEquals(err["operator 0"], "calls");
+    assertStrictEquals(err["stack trace 0"], stack0);
+
+    assertStrictEquals(
+      err["message 1"],
+      "Expected the fn function to be executed 1 time(s) but was executed 0 time(s).",
+    );
+    assertStrictEquals(err["actual 1"], 0);
+    assertStrictEquals(err["expected 1"], 1);
+    assertStrictEquals(err["operator 1"], "fn");
+    assertStrictEquals(err["stack trace 1"], stack1);
+  },
+});

std/node/util.ts

@@ -4,13 +4,34 @@ import * as types from "./_util/_util_types.ts";
 
 export { types };
 
+const DEFAULT_INSPECT_OPTIONS = {
+  showHidden: false,
+  depth: 2,
+  colors: false,
+  customInspect: true,
+  showProxy: false,
+  maxArrayLength: 100,
+  maxStringLength: Infinity,
+  breakLength: 80,
+  compact: 3,
+  sorted: false,
+  getters: false,
+};
+
+inspect.defaultOptions = DEFAULT_INSPECT_OPTIONS;
+inspect.custom = Deno.customInspect;
+
+// TODO(schwarzkopfb): make it in-line with Node's implementation
+// Ref: https://nodejs.org/dist/latest-v14.x/docs/api/util.html#util_util_inspect_object_options
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function inspect(object: unknown, ...opts: any): string {
+  opts = { ...DEFAULT_INSPECT_OPTIONS, ...opts };
   return Deno.inspect(object, {
-    depth: opts.depth ?? 4,
+    depth: opts.depth,
-    iterableLimit: opts.iterableLimit ?? 100,
+    iterableLimit: opts.maxArrayLength,
-    compact: !!(opts.compact ?? true),
+    compact: !!opts.compact,
-    sorted: !!(opts.sorted ?? false),
+    sorted: !!opts.sorted,
+    showProxy: !!opts.showProxy,
   });
 }