如何使用 jest 测试 Typescript 函数？
How to test a Typescript function using jest?
我正在尝试使用 Jest 编写 typescript 函数的测试，我正在尝试测试一些复杂的情况，但我不确定如何进行测试。示例场景，当接受字符串作为参数的函数改为接收数字时会发生什么。（通常不兼容的类型）
函数和测试
const removeDot=(value: string): string=>{ return value.toString().replace(/\./g, "-")}
//This works
expect(removeDot("..")).toBe("--")
// Testing this throw compile error
expect(removeDot(1)).toBe("--")
我想知道是否有最好的方法。
开玩笑配置
{
"preset": "ts-jest",
"verbose": true,
"globals": {
"ts-jest": {
"tsconfig": "tsconfig.json",
"babelConfig": false
}
},
"moduleFileExtensions": ["ts", "js", "json"],
"transform": {
".(ts|tsx)": "ts-jest"
},
"testEnvironment": "node",
"collectCoverage": true,
"coverageReporters": ["text"],
"collectCoverageFrom": ["./**/*.(tsx||ts)"],
"coverageThreshold": {
"global": {
"lines": 0,
"functions": 0,
"branches": 0,
"statements": 0
}
}
}
tsconfig
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Projects */
// "incremental": true, /* Enable incremental compilation */
// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
// "tsBuildInfoFile": "./", /* Specify the folder for .tsbuildinfo incremental compilation files. */
// "disableSourceOfProjectReferenceRedirect": true, /* Disable preferring source files instead of declaration files when referencing composite projects */
// "disableSolutionSearching": true, /* Opt a project out of multi-project reference checking when editing. */
// "disableReferencedProjectLoad": true, /* Reduce the number of projects loaded automatically by TypeScript. */
/* Language and Environment */
"target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
// "lib": [], /* Specify a set of bundled library declaration files that describe the target runtime environment. */
"jsx": "react" /* Specify what JSX code is generated. */,
// "experimentalDecorators": true, /* Enable experimental support for TC39 stage 2 draft decorators. */
// "emitDecoratorMetadata": true, /* Emit design-type metadata for decorated declarations in source files. */
// "jsxFactory": "", /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
// "jsxFragmentFactory": "", /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
// "jsxImportSource": "", /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
// "reactNamespace": "", /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
// "noLib": true, /* Disable including any library files, including the default lib.d.ts. */
// "useDefineForClassFields": true, /* Emit ECMAScript-standard-compliant class fields. */
/* Modules */
"module": "commonjs" /* Specify what module code is generated. */,
"rootDir": "./" /* Specify the root folder within your source files. */,
// "moduleResolution": "node", /* Specify how TypeScript looks up a file from a given module specifier. */
// "baseUrl": "./", /* Specify the base directory to resolve non-relative module names. */
// "paths": {}, /* Specify a set of entries that re-map imports to additional lookup locations. */
// "rootDirs": [], /* Allow multiple folders to be treated as one when resolving modules. */
"typeRoots": [
"./node_modules/@types"
] /* Specify multiple folders that act like `./node_modules/@types`. */,
"types": [
"node",
"jest"
] /* Specify type package names to be included without being referenced in a source file. */,
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
// "resolveJsonModule": true, /* Enable importing .json files */
// "noResolve": true, /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */
/* JavaScript Support */
// "allowJs": true, /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
// "checkJs": true, /* Enable error reporting in type-checked JavaScript files. */
// "maxNodeModuleJsDepth": 1, /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */
/* Emit */
// "declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
// "declarationMap": true, /* Create sourcemaps for d.ts files. */
// "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
// "sourceMap": true, /* Create source map files for emitted JavaScript files. */
// "outFile": "./", /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
"outDir": "./build/dist" /* Specify an output folder for all emitted files. */,
// "removeComments": true, /* Disable emitting comments. */
// "noEmit": true, /* Disable emitting files from a compilation. */
// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
// "importsNotUsedAsValues": "remove", /* Specify emit/checking behavior for imports that are only used for types */
// "downlevelIteration": true, /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
// "sourceRoot": "", /* Specify the root path for debuggers to find the reference source code. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
// "inlineSources": true, /* Include source code in the sourcemaps inside the emitted JavaScript. */
// "emitBOM": true, /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
// "newLine": "crlf", /* Set the newline character for emitting files. */
// "stripInternal": true, /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
// "noEmitHelpers": true, /* Disable generating custom helper functions like `__extends` in compiled output. */
// "noEmitOnError": true, /* Disable emitting files if any type checking errors are reported. */
// "preserveConstEnums": true, /* Disable erasing `const enum` declarations in generated code. */
// "declarationDir": "./", /* Specify the output directory for generated declaration files. */
// "preserveValueImports": true, /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
/* Interop Constraints */
// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
// "allowSyntheticDefaultImports": true, /* Allow 'import x from y' when a module doesn't have a default export. */
"esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
// "preserveSymlinks": true, /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
"forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
/* Type Checking */
"strict": true /* Enable all strict type-checking options. */,
"noImplicitAny": true /* Enable error reporting for expressions and declarations with an implied `any` type.. */,
"strictNullChecks": true /* When type checking, take into account `null` and `undefined`. */,
"strictFunctionTypes": true /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */,
"strictBindCallApply": true /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */,
"strictPropertyInitialization": true /* Check for class properties that are declared but not set in the constructor. */,
"noImplicitThis": true /* Enable error reporting when `this` is given the type `any`. */,
"useUnknownInCatchVariables": true /* Type catch clause variables as 'unknown' instead of 'any'. */,
"alwaysStrict": true /* Ensure 'use strict' is always emitted. */,
"noUnusedLocals": true /* Enable error reporting when a local variables aren't read. */,
"noUnusedParameters": true /* Raise an error when a function parameter isn't read */,
"exactOptionalPropertyTypes": true /* Interpret optional property types as written, rather than adding 'undefined'. */,
"noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
"noFallthroughCasesInSwitch": true /* Enable error reporting for fallthrough cases in switch statements. */,
"noUncheckedIndexedAccess": true /* Include 'undefined' in index signature results */,
"noImplicitOverride": true /* Ensure overriding members in derived classes are marked with an override modifier. */,
"noPropertyAccessFromIndexSignature": true /* Enforces using indexed accessors for keys declared using an indexed type */,
// "allowUnusedLabels": true, /* Disable error reporting for unused labels. */
// "allowUnreachableCode": true, /* Disable error reporting for unreachable code. */
/* Completeness */
// "skipDefaultLibCheck": true, /* Skip type checking .d.ts files that are included with TypeScript. */
"skipLibCheck": true /* Skip type checking all .d.ts files. */
}
}
jestjs用于测试运行时代码逻辑，不是编译时的静态类型。
对于TypeScript编写的测试源代码，您需要确保函数的参数是正确的类型。
value 参数的类型是 string，TSC 不允许您在编译时将数字传递给函数。如果希望函数处理数字参数，则应将类型修改为string | number。并且，您的运行时代码逻辑也应该更新。
removeDot 的参数已被 TSC 限制为 string 类型。此类型检查适用于 运行 代码和测试代码，除非开发人员故意将参数断言为 any 以绕过 TSC 类型检查。
我正在尝试使用 Jest 编写 typescript 函数的测试，我正在尝试测试一些复杂的情况，但我不确定如何进行测试。示例场景，当接受字符串作为参数的函数改为接收数字时会发生什么。（通常不兼容的类型）
函数和测试
const removeDot=(value: string): string=>{ return value.toString().replace(/\./g, "-")}
//This works
expect(removeDot("..")).toBe("--")
// Testing this throw compile error
expect(removeDot(1)).toBe("--")
我想知道是否有最好的方法。
开玩笑配置
{
"preset": "ts-jest",
"verbose": true,
"globals": {
"ts-jest": {
"tsconfig": "tsconfig.json",
"babelConfig": false
}
},
"moduleFileExtensions": ["ts", "js", "json"],
"transform": {
".(ts|tsx)": "ts-jest"
},
"testEnvironment": "node",
"collectCoverage": true,
"coverageReporters": ["text"],
"collectCoverageFrom": ["./**/*.(tsx||ts)"],
"coverageThreshold": {
"global": {
"lines": 0,
"functions": 0,
"branches": 0,
"statements": 0
}
}
}
tsconfig
{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */
/* Projects */
// "incremental": true, /* Enable incremental compilation */
// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
// "tsBuildInfoFile": "./", /* Specify the folder for .tsbuildinfo incremental compilation files. */
// "disableSourceOfProjectReferenceRedirect": true, /* Disable preferring source files instead of declaration files when referencing composite projects */
// "disableSolutionSearching": true, /* Opt a project out of multi-project reference checking when editing. */
// "disableReferencedProjectLoad": true, /* Reduce the number of projects loaded automatically by TypeScript. */
/* Language and Environment */
"target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
// "lib": [], /* Specify a set of bundled library declaration files that describe the target runtime environment. */
"jsx": "react" /* Specify what JSX code is generated. */,
// "experimentalDecorators": true, /* Enable experimental support for TC39 stage 2 draft decorators. */
// "emitDecoratorMetadata": true, /* Emit design-type metadata for decorated declarations in source files. */
// "jsxFactory": "", /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
// "jsxFragmentFactory": "", /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
// "jsxImportSource": "", /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
// "reactNamespace": "", /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
// "noLib": true, /* Disable including any library files, including the default lib.d.ts. */
// "useDefineForClassFields": true, /* Emit ECMAScript-standard-compliant class fields. */
/* Modules */
"module": "commonjs" /* Specify what module code is generated. */,
"rootDir": "./" /* Specify the root folder within your source files. */,
// "moduleResolution": "node", /* Specify how TypeScript looks up a file from a given module specifier. */
// "baseUrl": "./", /* Specify the base directory to resolve non-relative module names. */
// "paths": {}, /* Specify a set of entries that re-map imports to additional lookup locations. */
// "rootDirs": [], /* Allow multiple folders to be treated as one when resolving modules. */
"typeRoots": [
"./node_modules/@types"
] /* Specify multiple folders that act like `./node_modules/@types`. */,
"types": [
"node",
"jest"
] /* Specify type package names to be included without being referenced in a source file. */,
// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
// "resolveJsonModule": true, /* Enable importing .json files */
// "noResolve": true, /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */
/* JavaScript Support */
// "allowJs": true, /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
// "checkJs": true, /* Enable error reporting in type-checked JavaScript files. */
// "maxNodeModuleJsDepth": 1, /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */
/* Emit */
// "declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
// "declarationMap": true, /* Create sourcemaps for d.ts files. */
// "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
// "sourceMap": true, /* Create source map files for emitted JavaScript files. */
// "outFile": "./", /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
"outDir": "./build/dist" /* Specify an output folder for all emitted files. */,
// "removeComments": true, /* Disable emitting comments. */
// "noEmit": true, /* Disable emitting files from a compilation. */
// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
// "importsNotUsedAsValues": "remove", /* Specify emit/checking behavior for imports that are only used for types */
// "downlevelIteration": true, /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
// "sourceRoot": "", /* Specify the root path for debuggers to find the reference source code. */
// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
// "inlineSources": true, /* Include source code in the sourcemaps inside the emitted JavaScript. */
// "emitBOM": true, /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
// "newLine": "crlf", /* Set the newline character for emitting files. */
// "stripInternal": true, /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
// "noEmitHelpers": true, /* Disable generating custom helper functions like `__extends` in compiled output. */
// "noEmitOnError": true, /* Disable emitting files if any type checking errors are reported. */
// "preserveConstEnums": true, /* Disable erasing `const enum` declarations in generated code. */
// "declarationDir": "./", /* Specify the output directory for generated declaration files. */
// "preserveValueImports": true, /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
/* Interop Constraints */
// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
// "allowSyntheticDefaultImports": true, /* Allow 'import x from y' when a module doesn't have a default export. */
"esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
// "preserveSymlinks": true, /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
"forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
/* Type Checking */
"strict": true /* Enable all strict type-checking options. */,
"noImplicitAny": true /* Enable error reporting for expressions and declarations with an implied `any` type.. */,
"strictNullChecks": true /* When type checking, take into account `null` and `undefined`. */,
"strictFunctionTypes": true /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */,
"strictBindCallApply": true /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */,
"strictPropertyInitialization": true /* Check for class properties that are declared but not set in the constructor. */,
"noImplicitThis": true /* Enable error reporting when `this` is given the type `any`. */,
"useUnknownInCatchVariables": true /* Type catch clause variables as 'unknown' instead of 'any'. */,
"alwaysStrict": true /* Ensure 'use strict' is always emitted. */,
"noUnusedLocals": true /* Enable error reporting when a local variables aren't read. */,
"noUnusedParameters": true /* Raise an error when a function parameter isn't read */,
"exactOptionalPropertyTypes": true /* Interpret optional property types as written, rather than adding 'undefined'. */,
"noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
"noFallthroughCasesInSwitch": true /* Enable error reporting for fallthrough cases in switch statements. */,
"noUncheckedIndexedAccess": true /* Include 'undefined' in index signature results */,
"noImplicitOverride": true /* Ensure overriding members in derived classes are marked with an override modifier. */,
"noPropertyAccessFromIndexSignature": true /* Enforces using indexed accessors for keys declared using an indexed type */,
// "allowUnusedLabels": true, /* Disable error reporting for unused labels. */
// "allowUnreachableCode": true, /* Disable error reporting for unreachable code. */
/* Completeness */
// "skipDefaultLibCheck": true, /* Skip type checking .d.ts files that are included with TypeScript. */
"skipLibCheck": true /* Skip type checking all .d.ts files. */
}
}
jestjs用于测试运行时代码逻辑，不是编译时的静态类型。
对于TypeScript编写的测试源代码，您需要确保函数的参数是正确的类型。
value 参数的类型是 string，TSC 不允许您在编译时将数字传递给函数。如果希望函数处理数字参数，则应将类型修改为string | number。并且，您的运行时代码逻辑也应该更新。
removeDot 的参数已被 TSC 限制为 string 类型。此类型检查适用于 运行 代码和测试代码，除非开发人员故意将参数断言为 any 以绕过 TSC 类型检查。