@glint/type-test v1.4.0
@glint/type-test
This library contains template helpers for testing inferred types in Glint-enabled templates.
It's similar in concept to (and built on) the expect-type
library.
Usage
{{expectTypeOf "hello" to.beString}}
{{expectTypeOf 123 to.equalTypeOf 456}}
Strict-Mode Templates
For strict-mode templates, the expectTypeOf
helper and to
collection of expectations are
both directly importable from @glint/type-test
.
import { expectTypeOf, to } from '@glint/type-test';
let letters = ['a', 'b', 'c'];
<template>
{{#each letters as |letter index|}}
{{expectTypeOf letter to.beString}}
{{expectTypeOf index to.beNumber}}
{{/each}}
<template>
Loose-Mode Templates
For "classic" loose-mode Ember templates, @glint/type-test
provides a typeTest
wrapper that
will pass expectTypeOf
and to
to your template as args:
import { typeTest } from '@glint/type-test';
import { hbs } from 'ember-cli-htmlbars';
typeTest(
hbs`
{{#each (array 'a' 'b' 'c') as |letter index|}}
{{@expectTypeOf letter @to.beString}}
{{@expectTypeOf index @to.beNumber}}
{{/each}}
`
);
You can also optionally provide an initial this
value to typeTest
to make values available
in your template to either test inference against or to use as a basis for comparing type equality.
import { typeTest } from '@glint/type-test';
import { hbs } from 'ember-cli-htmlbars';
typeTest(
{ letters: ['a', 'b', 'c'] },
hbs`
{{#each this.letters as |letter index|}}
{{@expectTypeOf letter @to.beString}}
{{@expectTypeOf index @to.beNumber}}
{{/each}}
`
);
Expectations
This library provides a set of expectations to compare the type of a given value to common simple types.
import { expectTypeOf, to } from '@glint/type-test';
let symbolValue = Symbol('hi');
let anyValue: any = null;
let unknownValue: unknown = null;
let neverValue: never = (null as never);
<template>
{{expectTypeOf "hello" to.beString}}
{{expectTypeOf 123 to.beNumber}}
{{expectTypeOf true to.beBoolean}}
{{expectTypeOf symbolValue to.beSymbol}}
{{expectTypeOf anyValue to.beAny}}
{{expectTypeOf unknownValue to.beUnknown}}
{{expectTypeOf neverValue to.beNever}}
{{expectTypeOf null to.beNull}}
{{expectTypeOf undefined to.beUndefined}}
</template>
It also provides expectations that allow you to compare the type of one value to that of another.
import { expectTypeOf, to } from '@glint/type-test';
let a: 'a' | 'b' = 'a';
let b: 'a' | 'b' = 'b';
let hi: string = 'hi';
<template>
<!-- 'a' | 'b' is the same type as itself -->
{{expectTypeOf a to.equalTypeOf b}}
<!-- 'a' | 'b' is assignable to the more general type string -->
{{expectTypeOf a to.beAssignableToTypeOf hi}}
<!-- string is not the same type as 'a' | 'b' -->
{{! @glint-expect-error }}
{{expectTypeOf hi to.equalTypeOf a}}
<!-- string is not assignable to 'a' | 'b' -->
{{! @glint-expect-error }}
{{expectTypeOf hi to.beAssignableToTypeOf a}}
</template>
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