3.2 KiB
Enforce valid expect()
usage (valid-expect
)
Ensure expect()
is called with a single argument and there is an actual
expectation made.
Rule details
This rule triggers a warning if expect()
is called with more than one argument
or without arguments. It would also issue a warning if there is nothing called
on expect()
, e.g.:
expect();
expect('something');
or when a matcher function was not called, e.g.:
expect(true).toBeDefined;
or when an async assertion was not await
ed or returned, e.g.:
expect(Promise.resolve('Hi!')).resolves.toBe('Hi!');
This rule is enabled by default.
Options
{
type: 'object',
properties: {
alwaysAwait: {
type: 'boolean',
default: false,
},
minArgs: {
type: 'number',
minimum: 1,
},
maxArgs: {
type: 'number',
minimum: 1,
},
},
additionalProperties: false,
}
alwaysAwait
Enforces to use await
inside block statements. Using return
will trigger a
warning. Returning one line statements with arrow functions is always allowed.
Examples of incorrect code for the { "alwaysAwait": true } option:
// alwaysAwait: true
test('test1', async () => {
await expect(Promise.resolve(2)).resolves.toBeDefined();
return expect(Promise.resolve(1)).resolves.toBe(1); // `return` statement will trigger a warning
});
Examples of correct code for the { "alwaysAwait": true } option:
// alwaysAwait: true
test('test1', async () => {
await expect(Promise.resolve(2)).resolves.toBeDefined();
await expect(Promise.resolve(1)).resolves.toBe(1);
});
test('test2', () => expect(Promise.resolve(2)).resolves.toBe(2));
minArgs
& maxArgs
Enforces the minimum and maximum number of arguments that expect
can take, and
is required to take.
Both of these properties have a default value of 1
, which is the number of
arguments supported by vanilla expect
.
This is useful when you're using libraries that increase the number of arguments
supported by expect
, such as
jest-expect-message
.
Default configuration
The following patterns are considered warnings:
test('all the things', async () => {
expect();
expect().toEqual('something');
expect('something', 'else');
expect('something');
await expect('something');
expect(true).toBeDefined;
expect(Promise.resolve('hello')).resolves;
expect(Promise.resolve('hello')).resolves.toEqual('hello');
Promise.resolve(expect(Promise.resolve('hello')).resolves.toEqual('hello'));
Promise.all([
expect(Promise.resolve('hello')).resolves.toEqual('hello'),
expect(Promise.resolve('hi')).resolves.toEqual('hi'),
]);
});
The following patterns are not warnings:
test('all the things', async () => {
expect('something').toEqual('something');
expect([1, 2, 3]).toEqual([1, 2, 3]);
expect(true).toBeDefined();
await expect(Promise.resolve('hello')).resolves.toEqual('hello');
await Promise.resolve(
expect(Promise.resolve('hello')).resolves.toEqual('hello'),
);
await Promise.all(
expect(Promise.resolve('hello')).resolves.toEqual('hello'),
expect(Promise.resolve('hi')).resolves.toEqual('hi'),
);
});