2.1 KiB
No standalone expect in a describe block (no-standalone-expect
)
Prevents expect
statements outside of a test
or it
block. An expect
within a helper function (but outside of a test
or it
block) will not
trigger this rule.
Rule Details
This rule aims to eliminate expect
statements that will not be executed. An
expect
inside of a describe
block but outside of a test
or it
block or
outside of a describe
will not execute and therefore will trigger this rule.
It is viable, however, to have an expect
in a helper function that is called
from within a test
or it
block so expect
statements in a function will not
trigger this rule.
Statements like expect.hasAssertions()
will NOT trigger this rule since these
calls will execute if they are not in a test block.
Examples of incorrect code for this rule:
// in describe
describe('a test', () => {
expect(1).toBe(1);
});
// below other tests
describe('a test', () => {
it('an it', () => {
expect(1).toBe(1);
});
expect(1).toBe(1);
});
Examples of correct code for this rule:
// in it block
describe('a test', () => {
it('an it', () => {
expect(1).toBe(1);
});
});
// in helper function
describe('a test', () => {
const helper = () => {
expect(1).toBe(1);
};
it('an it', () => {
helper();
});
});
describe('a test', () => {
expect.hasAssertions(1);
});
*Note that this rule will not trigger if the helper function is never used even
thought the expect
will not execute. Rely on a rule like no-unused-vars for
this case.
Options
additionalTestBlockFunctions
This array can be used to specify the names of functions that should also be treated as test blocks:
{
"rules": {
"jest/no-standalone-expect": [
"error",
{ "additionalTestBlockFunctions": ["each.test"] }
]
}
}
The following is correct when using the above configuration:
each([
[1, 1, 2],
[1, 2, 3],
[2, 1, 3],
]).test('returns the result of adding %d to %d', (a, b, expected) => {
expect(a + b).toBe(expected);
});
When Not To Use It
Don't use this rule on non-jest test files.