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Give better assertion messages when using our own methods for assert.…
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…all & assert.any (Fixes #107)
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@bjornstar
bjornstar committed Aug 7, 2023
1 parent 5044c91 commit 8ca56da
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Showing 2 changed files with 174 additions and 26 deletions.
161 changes: 144 additions & 17 deletions source/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -794,10 +794,33 @@ function typeErrorMessage(description: AssertionTypeDescription, value: unknown)
return `Expected value which is \`${description}\`, received value of type \`${is(value)}\`.`;
}

function typeErrorMessageMultipleValue(description: AssertionTypeDescription, values: unknown[]): string {
function unique<T>(values: T[]): T[] {
// eslint-disable-next-line unicorn/prefer-spread
const valueTypes = Array.from(new Set(values.map(singleValue => `\`${is(singleValue)}\``))).join(', ');
return `Expected value which is \`${description}\`, received values of types ${valueTypes}.`;
return Array.from(new Set(values));
}

function joinWithWord(values: string[], word: 'and' | 'or'): string {
switch (values.length) {
case 0:
case 1: {
return values.join('');
}

case 2: {
return values.join(` ${word} `);
}

default: {
// TODO: Replace with .at after node v14 support is dropped
return `${[...values].slice(0, -1).join(', ')}, ${word} ${values[values.length - 1] ?? ''}`;
}
}
}

function typeErrorMessageMultipleValues(expectedType: AssertionTypeDescription | AssertionTypeDescription[], values: unknown[]): string {
const uniqueExpectedTypes = unique((isArray(expectedType) ? expectedType : [expectedType]).map(value => `\`${value}\``));
const uniqueValueTypes = unique(values.map(value => `\`${is(value)}\``));
return `Expected values which are ${joinWithWord(uniqueExpectedTypes, 'or')}. Received values of type${uniqueValueTypes.length > 1 ? 's' : ''} ${joinWithWord(uniqueValueTypes, 'and')}.`;
}

// Type assertions have to be declared with an explicit type.
Expand Down Expand Up @@ -1011,15 +1034,119 @@ export const assert: Assert = {
whitespaceString: assertWhitespaceString,
};

const methodTypeMap = {
isArray: 'Array',
isArrayBuffer: 'ArrayBuffer',
isArrayLike: 'array-like',
isAsyncFunction: 'AsyncFunction',
isAsyncGenerator: 'AsyncGenerator',
isAsyncGeneratorFunction: 'AsyncGeneratorFunction',
isAsyncIterable: 'AsyncIterable',
isBigint: 'bigint',
isBigInt64Array: 'BigInt64Array',
isBigUint64Array: 'BigUint64Array',
isBlob: 'Blob',
isBoolean: 'boolean',
isBoundFunction: 'Function',
isBuffer: 'Buffer',
isClass: 'Class',
isDataView: 'DataView',
isDate: 'Date',
isDirectInstanceOf: 'T',
isDomElement: 'HTMLElement',
isEmptyArray: 'empty array',
isEmptyMap: 'empty map',
isEmptyObject: 'empty object',
isEmptySet: 'empty set',
isEmptyString: 'empty string',
isEmptyStringOrWhitespace: 'empty string or whitespace',
isEnumCase: 'EnumCase',
isError: 'Error',
isEvenInteger: 'even integer',
isFalsy: 'falsy',
isFloat32Array: 'Float32Array',
isFloat64Array: 'Float64Array',
isFormData: 'FormData',
isFunction: 'Function',
isGenerator: 'Generator',
isGeneratorFunction: 'GeneratorFunction',
isInfinite: 'infinite number',
isInRange: 'in range',
isInt16Array: 'Int16Array',
isInt32Array: 'Int32Array',
isInt8Array: 'Int8Array',
isInteger: 'integer',
isIterable: 'Iterable',
isMap: 'Map',
isNan: 'NaN',
isNativePromise: 'native Promise',
isNegativeNumber: 'negative number',
isNodeStream: 'Node.js Stream',
isNonEmptyArray: 'non-empty array',
isNonEmptyMap: 'non-empty map',
isNonEmptyObject: 'non-empty object',
isNonEmptySet: 'non-empty set',
isNonEmptyString: 'non-empty string',
isNonEmptyStringAndNotWhitespace: 'non-empty string and not whitespace',
isNull: 'null',
isNullOrUndefined: 'null or undefined',
isNumber: 'number',
isNumericString: 'string with a number',
isObject: 'Object',
isObservable: 'Observable',
isOddInteger: 'odd integer',
isPlainObject: 'plain object',
isPositiveNumber: 'positive number',
isPrimitive: 'primitive',
isPromise: 'Promise',
isPropertyKey: 'PropertyKey',
isRegExp: 'RegExp',
isSafeInteger: 'integer',
isSet: 'Set',
isSharedArrayBuffer: 'SharedArrayBuffer',
isString: 'string',
isSymbol: 'symbol',
isTruthy: 'truthy',
isTupleLike: 'tuple-like',
isTypedArray: 'TypedArray',
isUint16Array: 'Uint16Array',
isUint32Array: 'Uint32Array',
isUint8Array: 'Uint8Array',
isUint8ClampedArray: 'Uint8ClampedArray',
isUndefined: 'undefined',
isUrlInstance: 'URL',
isUrlSearchParams: 'URLSearchParams',
isUrlString: 'string with a URL',
isValidLength: 'valid length',
isWeakMap: 'WeakMap',
isWeakRef: 'WeakRef',
isWeakSet: 'WeakSet',
isWhitespaceString: 'whitespace string',
} as const;

function keysOf<T extends Record<PropertyKey, unknown>>(value: T): Array<keyof T> {
return Object.keys(value) as Array<keyof T>;
}

type IsMethodName = keyof typeof methodTypeMap;
const isMethodNames: IsMethodName[] = keysOf(methodTypeMap);

function isIsMethodName(value: unknown): value is IsMethodName {
return isMethodNames.includes(value as IsMethodName);
}

export function assertAll(predicate: Predicate, ...values: unknown[]): void | never {
if (!isAll(predicate, ...values)) {
throw new TypeError(typeErrorMessageMultipleValue('predicate returns truthy for all values', values));
const expectedType = isIsMethodName(predicate.name) ? methodTypeMap[predicate.name] : 'predicate returns truthy for all values';
throw new TypeError(typeErrorMessageMultipleValues(expectedType, values));
}
}

export function assertAny(predicate: Predicate | Predicate[], ...values: unknown[]): void | never {
if (!isAny(predicate, ...values)) {
throw new TypeError(typeErrorMessageMultipleValue('predicate returns truthy for any value', values));
const predicates = isArray(predicate) ? predicate : [predicate];
const expectedTypes = predicates.map(predicate => isIsMethodName(predicate.name) ? methodTypeMap[predicate.name] : 'predicate returns truthy for any value');
throw new TypeError(typeErrorMessageMultipleValues(expectedTypes, values));
}
}

Expand Down Expand Up @@ -1138,6 +1265,12 @@ export function assertDirectInstanceOf<T>(instance: unknown, class_: Class<T>):
}
}

export function assertDomElement(value: unknown): asserts value is HTMLElement {
if (!isDomElement(value)) {
throw new TypeError(typeErrorMessage('HTMLElement', value));
}
}

export function assertEmptyArray(value: unknown): asserts value is never[] {
if (!isEmptyArray(value)) {
throw new TypeError(typeErrorMessage('empty array', value));
Expand Down Expand Up @@ -1235,12 +1368,6 @@ export function assertGeneratorFunction(value: unknown): asserts value is Genera
}
}

export function assertDomElement(value: unknown): asserts value is HTMLElement {
if (!isDomElement(value)) {
throw new TypeError(typeErrorMessage('HTMLElement', value));
}
}

export function assertInfinite(value: unknown): asserts value is number {
if (!isInfinite(value)) {
throw new TypeError(typeErrorMessage('infinite number', value));
Expand Down Expand Up @@ -1283,12 +1410,6 @@ export function assertIterable<T = unknown>(value: unknown): asserts value is It
}
}

export function assertNativePromise<T = unknown>(value: unknown): asserts value is Promise<T> {
if (!isNativePromise(value)) {
throw new TypeError(typeErrorMessage('native Promise', value));
}
}

export function assertMap<Key = unknown, Value = unknown>(value: unknown): asserts value is Map<Key, Value> {
if (!isMap(value)) {
throw new TypeError(typeErrorMessage('Map', value));
Expand All @@ -1301,6 +1422,12 @@ export function assertNan(value: unknown): asserts value is number {
}
}

export function assertNativePromise<T = unknown>(value: unknown): asserts value is Promise<T> {
if (!isNativePromise(value)) {
throw new TypeError(typeErrorMessage('native Promise', value));
}
}

export function assertNegativeNumber(value: unknown): asserts value is number {
if (!isNegativeNumber(value)) {
throw new TypeError(typeErrorMessage('negative number', value));
Expand Down
39 changes: 30 additions & 9 deletions test/test.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1960,22 +1960,36 @@ test('is.any', t => {
t.throws(() => {
assert.any(is.string, 1, 2, 3);
}, {
// Removes duplicates:
message: /received values of types `number`./,
// Includes expected type and removes duplicates from received types:
message: /Expected values which are `string`. Received values of type `number`./,
});

t.throws(() => {
assert.any(is.string, 1, [4]);
}, {
// Lists all types:
message: /received values of types `number`, `Array`./,
// Includes expected type and lists all received types:
message: /Expected values which are `string`. Received values of types `number` and `Array`./,
});

t.throws(() => {
assert.any([is.string, is.nullOrUndefined], 1);
}, {
// Handles array as first argument:
message: /received values of types `number`./,
message: /Expected values which are `string` or `null or undefined`. Received values of type `number`./,
});

t.throws(() => {
assert.any([is.string, is.number, is.boolean], null, undefined, Number.NaN);
}, {
// Handles more than 2 expected and received types:
message: /Expected values which are `string`, `number`, or `boolean`. Received values of types `null`, `undefined`, and `NaN`./,
});

t.throws(() => {
assert.any(() => false, 1);
}, {
// Default type assertion message
message: /Expected values which are `predicate returns truthy for any value`./,
});
});

Expand Down Expand Up @@ -2024,15 +2038,22 @@ test('is.all', t => {
t.throws(() => {
assert.all(is.string, 1, 2, 3);
}, {
// Removes duplicates:
message: /received values of types `number`./,
// Includes expected type and removes duplicates from received types:
message: /Expected values which are `string`. Received values of type `number`./,
});

t.throws(() => {
assert.all(is.string, 1, [4]);
}, {
// Lists all types:
message: /received values of types `number`, `Array`./,
// Includes expected type and lists all received types:
message: /Expected values which are `string`. Received values of types `number` and `Array`./,
});

t.throws(() => {
assert.all(() => false, 1);
}, {
// Default type assertion message
message: /Expected values which are `predicate returns truthy for all values`./,
});
});

Expand Down

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