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Fix type guard for isWhitespaceString and isEmptyStringOrWhitespace (#207)

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Martin Eneqvist 2024-06-26 14:31:56 +02:00 • committed by GitHub
parent 8cbcaee674
commit 25a376875d
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3 changed files with 14 additions and 4 deletions
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9
source/index.ts
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@ -10,6 +10,7 @@ import type {
Primitive, Primitive,
TypedArray, TypedArray,
WeakRef, WeakRef,
Whitespace,
} from './types.js'; } from './types.js';
const typedArrayTypeNames = [ const typedArrayTypeNames = [
@ -435,7 +436,7 @@ export function isEmptyString(value: unknown): value is '' {
return isString(value) && value.length === 0; return isString(value) && value.length === 0;
} }
export function isEmptyStringOrWhitespace(value: unknown): value is string { export function isEmptyStringOrWhitespace(value: unknown): value is '' | Whitespace {
return isEmptyString(value) || isWhitespaceString(value); return isEmptyString(value) || isWhitespaceString(value);
} }
@ -777,7 +778,7 @@ export function isWeakSet(value: unknown): value is WeakSet<object> {
return getObjectType(value) === 'WeakSet'; return getObjectType(value) === 'WeakSet';
} }
export function isWhitespaceString(value: unknown): value is string { export function isWhitespaceString(value: unknown): value is Whitespace {
return isString(value) && /^\s+$/.test(value); return isString(value) && /^\s+$/.test(value);
} }
@ -893,7 +894,7 @@ type Assert = {
emptyArray: (value: unknown, message?: string) => asserts value is never[]; emptyArray: (value: unknown, message?: string) => asserts value is never[];
nonEmptyArray: <T = unknown, Item = unknown>(value: T | Item[], message?: string) => asserts value is [Item, ...Item[]]; nonEmptyArray: <T = unknown, Item = unknown>(value: T | Item[], message?: string) => asserts value is [Item, ...Item[]];
emptyString: (value: unknown, message?: string) => asserts value is ''; emptyString: (value: unknown, message?: string) => asserts value is '';
emptyStringOrWhitespace: (value: unknown, message?: string) => asserts value is string; emptyStringOrWhitespace: (value: unknown, message?: string) => asserts value is '' | Whitespace;
nonEmptyString: (value: unknown, message?: string) => asserts value is string; nonEmptyString: (value: unknown, message?: string) => asserts value is string;
nonEmptyStringAndNotWhitespace: (value: unknown, message?: string) => asserts value is string; nonEmptyStringAndNotWhitespace: (value: unknown, message?: string) => asserts value is string;
emptyObject: <Key extends keyof any = string>(value: unknown, message?: string) => asserts value is Record<Key, never>; emptyObject: <Key extends keyof any = string>(value: unknown, message?: string) => asserts value is Record<Key, never>;
@ -1277,7 +1278,7 @@ export function assertEmptyString(value: unknown, message?: string): asserts val
} }
} }
export function assertEmptyStringOrWhitespace(value: unknown, message?: string): asserts value is string { export function assertEmptyStringOrWhitespace(value: unknown, message?: string): asserts value is '' | Whitespace {
if (!isEmptyStringOrWhitespace(value)) { if (!isEmptyStringOrWhitespace(value)) {
throw new TypeError(message ?? typeErrorMessage('empty string or whitespace', value)); throw new TypeError(message ?? typeErrorMessage('empty string or whitespace', value));
} }

2
source/types.ts
View file

@ -73,3 +73,5 @@ export type NodeStream = {
export type Predicate = (value: unknown) => boolean; export type Predicate = (value: unknown) => boolean;
export type NonEmptyString = string & {0: string}; export type NonEmptyString = string & {0: string};
export type Whitespace = ' ';

7
test/test.ts
View file

@ -1793,6 +1793,13 @@ test('is.emptyStringOrWhitespace', t => {
t.throws(() => { t.throws(() => {
assert.emptyStringOrWhitespace('unicorn'); assert.emptyStringOrWhitespace('unicorn');
}); });
let value = 'test'; // eslint-disable-line prefer-const -- can't use `const` here because then it will be inferred as `never` in the `if` block
if (is.emptyStringOrWhitespace(value)) {
value.charAt(0); // Should be inferred as `'' | Whitespace` and not `never`
} else {
value.charAt(0); // Should be inferred as `string` and not `never`
}
}); });
test('is.nonEmptyString', t => { test('is.nonEmptyString', t => {