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npm install -g jest
jest init命令在根目录创建 jest.config.js文件，没有这个文件中的几个配置我运行失败，所以记录一下
// 配置文档
//https://jestjs.io/docs/zh-Hans/configuration
module.exports = {
// All imported modules in your tests should be mocked automatically
// automock: false,
// Stop running tests after the first failure
// bail: false,
// Respect "browser" field in package.json when resolving modules
// browser: false,
// The directory where Jest should store its cached dependency information
// cacheDirectory: "C:\\Users\\h\\AppData\\Local\\Temp\\jest",
// Automatically clear mock calls and instances between every test
clearMocks: true,
// Indicates whether the coverage information should be collected while executing the test
// collectCoverage: false,
// An array of glob patterns indicating a set of files for which coverage information should be collected
// collectCoverageFrom: null,
// The directory where Jest should output its coverage files
coverageDirectory: "coverage",
// An array of regexp pattern strings used to skip coverage collection
// coveragePathIgnorePatterns: [
// "\\\\node_modules\\\\"
// ],
// A list of reporter names that Jest uses when writing coverage reports
// coverageReporters: [
// "json",
// "text",
// "lcov",
// "clover"
// ],
// An object that configures minimum threshold enforcement for coverage results
// coverageThreshold: null,
// Make calling deprecated APIs throw helpful error messages
// errorOnDeprecated: false,
// Force coverage collection from ignored files usin a array of glob patterns
// forceCoverageMatch: [],
// A path to a module which exports an async function that is triggered once before all test suites
// globalSetup: null,
// A path to a module which exports an async function that is triggered once after all test suites
// globalTeardown: null,
// A set of global variables that need to be available in all test environments
// globals: {},
// An array of directory names to be searched recursively up from the requiring module's location
// moduleDirectories: [
// "node_modules"
// ],
// An array of file extensions your modules use
// moduleFileExtensions: [
// "js",
// "json",
// "jsx",
// "node"
// ],
// A map from regular expressions to module names that allow to stub out resources with a single module
// moduleNameMapper: {},
// An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
// modulePathIgnorePatterns: [],
// Activates notifications for test results
// notify: false,
// An enum that specifies notification mode. Requires { notify: true }
// notifyMode: "always",
// A preset that is used as a base for Jest's configuration
// preset: null,
// Run tests from one or more projects
// projects: null,
// Use this configuration option to add custom reporters to Jest
// reporters: undefined,
// Automatically reset mock state between every test
// resetMocks: false,
// Reset the module registry before running each individual test
// resetModules: false,
// A path to a custom resolver
// resolver: null,
// Automatically restore mock state between every test
// restoreMocks: false,
// The root directory that Jest should scan for tests and modules within
// rootDir: null,
// A list of paths to directories that Jest should use to search for files in
// roots: [
// "<rootDir>"
// ],
// Allows you to use a custom runner instead of Jest's default test runner
// runner: "jest-runner",
// The paths to modules that run some code to configure or set up the testing environment before each test
// setupFiles: [],
// The path to a module that runs some code to configure or set up the testing framework before each test
// setupTestFrameworkScriptFile: null,
// A list of paths to snapshot serializer modules Jest should use for snapshot testing
// snapshotSerializers: [],
// The test environment that will be used for testing
testEnvironment: "node",
// Options that will be passed to the testEnvironment
// testEnvironmentOptions: {},
// Adds a location field to test results
// testLocationInResults: false,
// The glob patterns Jest uses to detect test files
// testMatch: [
// "**/__tests__/**/*.js?(x)",
// "**/?(*.)+(spec|test).js?(x)"
// ],
// An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
// testPathIgnorePatterns: [
// "\\\\node_modules\\\\"
// ],
// The regexp pattern Jest uses to detect test files
// testRegex: "",
// This option allows the use of a custom results processor
// testResultsProcessor: null,
// This option allows use of a custom test runner
// testRunner: "jasmine2",
// This option sets the URL for the jsdom environment. It is reflected in properties such as location.href
// testURL: "about:blank",
// Setting this value to "fake" allows the use of fake timers for functions such as "setTimeout"
// timers: "real",
// A map from regular expressions to paths to transformers
// transform: null,
// An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
// transformIgnorePatterns: [
// "\\\\node_modules\\\\"
// ],
// An array of regexp pattern strings that are matched against all modules before the module loader will automatically return a mock for them
// unmockedModulePathPatterns: undefined,
// Indicates whether each individual test should be reported during the run
// verbose: null,
// An array of regexp patterns that are matched against all source file paths before re-running tests in watch mode
// watchPathIgnorePatterns: [],
// Whether to use watchman for file crawling
// watchman: true,
};
让我们从写一个两个数相加的示例函数开始。首先，创建一个 sum.js 文件︰
function sum(a, b) {
return a + b;
}
module.exports = sum;
然后，创建一个名为 sum.test.js 的文件。这将包含我们的实际测试︰
const sum = require('./sum');
test('adds 1 + 2 to equal 3', () => {
expect(sum(1, 2)).toBe(3);
});
将下面的配置部分添加到你的 package.json 里面：
{
"scripts": {
"test": "jest"
}
}
最后，运行 yarn test
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