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Testing Error Handling Implementation in google/zx

This comprehensive test suite validates error handling and message formatting functionality in the Google ZX project. It covers various error scenarios, exit code handling, and stack trace parsing using TypeScript and Jest framework.

Test Coverage Overview

The test suite provides thorough coverage of error handling utilities including:

Exit code information retrieval and formatting
Errno message mapping and handling
Stack trace parsing for different JavaScript engines (V8, JSC)
Caller location extraction and formatting

Implementation Analysis

The testing approach utilizes Node’s native test framework with TypeScript integration. It implements describe/test blocks for organized test grouping and employs assert statements for validation. The implementation demonstrates both synchronous and asynchronous testing patterns with proper error object handling.

Technical Details

Key technical components include:

Node.js assert module for assertions
TypeScript type checking for error objects
Regular expressions for stack trace parsing
Modular test organization with nested describe blocks

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Comprehensive error case coverage including edge cases
Clear test naming and organization
Isolation of test cases
Type-safe testing with TypeScript interfaces
Proper error message validation

google/zx

test/error.test.ts

            
// Copyright 2024 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import assert from 'node:assert'
import { test, describe } from 'node:test'
import {
  getErrnoMessage,
  getExitCodeInfo,
  getCallerLocation,
  getCallerLocationFromString,
  formatExitMessage,
  formatErrorMessage,
} from '../src/error.ts'

describe('error', () => {
  test('getExitCodeInfo()', () => {
    assert.equal(getExitCodeInfo(2), 'Misuse of shell builtins')
  })

  test('getErrnoMessage()', () => {
    assert.equal(getErrnoMessage(-2), 'No such file or directory')
    assert.equal(getErrnoMessage(1e9), 'Unknown error')
    assert.equal(getErrnoMessage(undefined), 'Unknown error')
  })

  describe('getCallerLocation()', () => {
    assert.match(getCallerLocation(new Error('Foo')), /Suite\.runInAsyncScope/)
  })

  describe('getCallerLocationFromString()', () => {
    test('empty', () => {
      assert.equal(getCallerLocationFromString(), 'unknown')
    })

    test('no-match', () => {
      assert.equal(
        getCallerLocationFromString('stack\nstring'),
        'stack\nstring'
      )
    })

    test(`getCallerLocationFromString-v8`, () => {
      const stack = `
    Error
      at getCallerLocation (/Users/user/test.js:22:17)
      at e (/Users/user/test.js:34:13)
      at d (/Users/user/test.js:11:5)
      at c (/Users/user/test.js:8:5)
      at b (/Users/user/test.js:5:5)
      at a (/Users/user/test.js:2:5)
      at Object.<anonymous> (/Users/user/test.js:37:1)
      at Module._compile (node:internal/modules/cjs/loader:1254:14)
      at Module._extensions..js (node:internal/modules/cjs/loader:1308:10)
      at Module.load (node:internal/modules/cjs/loader:1117:32)
      at Module._load (node:internal/modules/cjs/loader:958:12)
    `
      assert.match(getCallerLocationFromString(stack), /^.*:11:5.*$/)
    })

    test(`getCallerLocationFromString-JSC`, () => {
      const stack = `
    getCallerLocation@/Users/user/test.js:22:17
    e@/Users/user/test.js:34:13
    d@/Users/user/test.js:11:5
    c@/Users/user/test.js:8:5
    b@/Users/user/test.js:5:5
    a@/Users/user/test.js:2:5
    module code@/Users/user/test.js:37:1
    evaluate@[native code]
    moduleEvaluation@[native code]
    moduleEvaluation@[native code]
    @[native code]
    asyncFunctionResume@[native code]
    promiseReactionJobWithoutPromise@[native code]
    promiseReactionJob@[native code]
    d@/Users/user/test.js:11:5
  `
      assert.match(getCallerLocationFromString(stack), /^.*:11:5.*$/)
    })
  })

  test('getExitMessage()', () => {
    assert.match(formatExitMessage(2, null, '', ''), /Misuse of shell builtins/)
    assert.match(formatExitMessage(1, 'SIGKILL', '', ''), /SIGKILL/)
  })

  test('getErrorMessage()', () => {
    assert.match(
      formatErrorMessage({ errno: -2 } as NodeJS.ErrnoException, ''),
      /No such file or directory/
    )
    assert.match(
      formatErrorMessage({ errno: -1e9 } as NodeJS.ErrnoException, ''),
      /Unknown error/
    )
    assert.match(
      formatErrorMessage({} as NodeJS.ErrnoException, ''),
      /Unknown error/
    )
  })
})