prefer-result-matchers

テスト内で @praha/byethrow-testing の toBeSuccess() / toBeFailure() を使用することを強制します。

ルールの詳細

Result.isSuccess(result) を呼び出してbooleanをアサートするのは冗長です。専用のマッチャー toBeSuccess() と toBeFailure() はより短く、失敗時のメッセージもわかりやすく、オプションのコールバック内で型も絞り込まれます。このルールは自動修正に対応しています。

@praha/byethrow-testing のセットアップ方法はテストを参照してください。

誤り

import { import ResultResult } from '@praha/byethrow';
import { const expect: ExpectStaticexpect } from 'vitest';

const const result: Result.Result<string, Error>result: import ResultResult.type Result<T, E> = Result.Success<T> | Result.Failure<E>A union type representing either a success or a failure.
@typeParamT  - The type of the Success value.@typeParamE  - The type of the Failure value.@exampleimport { Result } from '@praha/byethrow';

const doSomething = (): Result.Result<number, string> => {
  return Math.random() > 0.5
    ? { type: 'Success', value: 10 }
    : { type: 'Failure', error: 'Oops' };
};
@categoryCore  TypesResult<string, Error> = import ResultResult.const succeed: <"hello">(value: "hello") => Result.Result<"hello", never> (+1 overload)succeed('hello');

// ❌ isSuccess / isFailureのboolean戻り値をアサート
expect<boolean>(actual: boolean, message?: string): Assertion<boolean> (+1 overload)expect(import ResultResult.const isSuccess: <Result.Result<string, Error>>(result: Result.Result<string, Error>) => result is Result.Success<string>Type guard to check if a
Result
is a
Success 
.
@function@typeParamR  - The type of the result to check.@paramresult  - The Result to check.@returnstrue if the result is a Success , otherwise false.@exampleimport { Result } from '@praha/byethrow';

const result: Result.Result<number, string> = { type: 'Success', value: 10 };
if (Result.isSuccess(result)) {
  console.log(result.value); // Safe access to value
}
@categoryType  GuardsisSuccess(const result: Result.Result<string, Error>result)).JestAssertion<boolean>.toBe: <boolean>(expected: boolean) => voidChecks that a value is what you expect. It calls Object.is to compare values.
Don't use toBe with floating-point numbers.
@exampleexpect (result).toBe(42);
expect(status).toBe(true);toBe(true);
expect<boolean>(actual: boolean, message?: string): Assertion<boolean> (+1 overload)expect(import ResultResult.const isFailure: <Result.Result<string, Error>>(result: Result.Result<string, Error>) => result is Result.Failure<Error>Type guard to check if a
Result
is a
Failure 
.
@function@typeParamR  - The type of the result to check.@paramresult  - The Result to check.@returnstrue if the result is a Failure , otherwise false.@exampleimport { Result } from '@praha/byethrow';

const result: Result.Result<number, string> = { type: 'Failure', error: 'Something went wrong' };
if (Result.isFailure(result)) {
  console.error(result.error); // Safe access to error
}
@categoryType  GuardsisFailure(const result: Result.Result<string, Error>result)).JestAssertion<boolean>.toBeTruthy: () => voidUse when you don't care what a value is, you just want to ensure a value
is true in a boolean context. In JavaScript, there are six falsy values:
false, 0, '', null, undefined, and NaN. Everything else is truthy.
@exampleexpect (user.isActive).toBeTruthy();toBeTruthy();
expect<boolean>(actual: boolean, message?: string): Assertion<boolean> (+1 overload)expect(import ResultResult.const isSuccess: <Result.Result<string, Error>>(result: Result.Result<string, Error>) => result is Result.Success<string>Type guard to check if a
Result
is a
Success 
.
@function@typeParamR  - The type of the result to check.@paramresult  - The Result to check.@returnstrue if the result is a Success , otherwise false.@exampleimport { Result } from '@praha/byethrow';

const result: Result.Result<number, string> = { type: 'Success', value: 10 };
if (Result.isSuccess(result)) {
  console.log(result.value); // Safe access to value
}
@categoryType  GuardsisSuccess(const result: Result.Result<string, Error>result)).not: Assertion<boolean>not.JestAssertion<boolean>.toBe: <boolean>(expected: boolean) => voidChecks that a value is what you expect. It calls Object.is to compare values.
Don't use toBe with floating-point numbers.
@exampleexpect (result).toBe(42);
expect(status).toBe(true);toBe(false);

正しい

import { import ResultResult } from '@praha/byethrow';
import { const expect: ExpectStaticexpect } from 'vitest';

const const result: Result.Result<string, Error>result: import ResultResult.type Result<T, E> = Result.Success<T> | Result.Failure<E>A union type representing either a success or a failure.
@typeParamT  - The type of the Success value.@typeParamE  - The type of the Failure value.@exampleimport { Result } from '@praha/byethrow';

const doSomething = (): Result.Result<number, string> => {
  return Math.random() > 0.5
    ? { type: 'Success', value: 10 }
    : { type: 'Failure', error: 'Oops' };
};
@categoryCore  TypesResult<string, Error> = import ResultResult.const succeed: <"hello">(value: "hello") => Result.Result<"hello", never> (+1 overload)succeed('hello');

// ✅ 専用マッチャーを使用
expect<Result.Result<string, Error>>(actual: Result.Result<string, Error>, message?: string): Assertion<Result.Result<string, Error>> (+1 overload)expect(const result: Result.Result<string, Error>result).ResultMatchers<Result<string, Error>>.toBeSuccess: (callback?: ((value: string) => void) | undefined) => voidtoBeSuccess();
expect<Result.Result<string, Error>>(actual: Result.Result<string, Error>, message?: string): Assertion<Result.Result<string, Error>> (+1 overload)expect(const result: Result.Result<string, Error>result).ResultMatchers<Result<string, Error>>.toBeFailure: (callback?: ((error: Error) => void) | undefined) => voidtoBeFailure();

コールバックで内部の値をアサートする場合:

import { import ResultResult } from '@praha/byethrow';
import { const expect: ExpectStaticexpect } from 'vitest';

const const result: Result.Result<string, Error>result: import ResultResult.type Result<T, E> = Result.Success<T> | Result.Failure<E>A union type representing either a success or a failure.
@typeParamT  - The type of the Success value.@typeParamE  - The type of the Failure value.@exampleimport { Result } from '@praha/byethrow';

const doSomething = (): Result.Result<number, string> => {
  return Math.random() > 0.5
    ? { type: 'Success', value: 10 }
    : { type: 'Failure', error: 'Oops' };
};
@categoryCore  TypesResult<string, Error> = import ResultResult.const succeed: <"hello">(value: "hello") => Result.Result<"hello", never> (+1 overload)succeed('hello');

expect<Result.Result<string, Error>>(actual: Result.Result<string, Error>, message?: string): Assertion<Result.Result<string, Error>> (+1 overload)expect(const result: Result.Result<string, Error>result).ResultMatchers<Result<string, Error>>.toBeSuccess: (callback?: ((value: string) => void) | undefined) => voidtoBeSuccess((value: stringvalue) => {
  expect<string>(actual: string, message?: string): Assertion<string> (+1 overload)expect(value: stringvalue).JestAssertion<string>.toBe: <number>(expected: number) => voidChecks that a value is what you expect. It calls Object.is to compare values.
Don't use toBe with floating-point numbers.
@exampleexpect (result).toBe(42);
expect(status).toBe(true);toBe(42);
});

expect<Result.Result<string, Error>>(actual: Result.Result<string, Error>, message?: string): Assertion<Result.Result<string, Error>> (+1 overload)expect(const result: Result.Result<string, Error>result).ResultMatchers<Result<string, Error>>.toBeFailure: (callback?: ((error: Error) => void) | undefined) => voidtoBeFailure((error: Errorerror) => {
  expect<Error>(actual: Error, message?: string): Assertion<Error> (+1 overload)expect(error: Errorerror).JestAssertion<Error>.toBeInstanceOf: <ErrorConstructor>(expected: ErrorConstructor) => voidEnsure that an object is an instance of a class.
This matcher uses instanceof underneath.
@exampleexpect (new Date()).toBeInstanceOf(Date);toBeInstanceOf(var Error: ErrorConstructorError);
});

#prefer-result-matchers

#ルールの詳細

#誤り

#正しい

prefer-result-matchers

ルールの詳細

誤り

正しい