and

Can be used to separate single assertions.

For instance expect(1).isLessThan(2).and.isGreaterThan(0) creates two assertions (not one assertion with two sub-assertions) - the first asserts that 1 is less than 2 and the second asserts that 1 is greater than 0. If the first assertion fails, then the second assertion is not evaluated.

// and is just a filler word does not have any behaviour
expect(13).isGreaterThan(5).and.isLessThan(20)

// i.e. the above is equivalent to:
expect(13).isGreaterThan(5).isLessThan(20)

Return
An Expect for the current subject of the assertion.

Can be used to create a group of sub assertions when using the fluent API.

For instance assert(1).isLessThan(3).and { isEven(); isGreaterThan(1) } creates two assertions where the second one consists of two sub-assertions. In case the first assertion holds, then the second one is evaluated as a whole. Meaning, even though 1 is not even, it still evaluates that 1 is greater than 1. Hence the reporting might (depending on the configured Reporter) contain both failing sub-assertions.

expect(13).isA<Int>().and {
    isGreaterThan(5)
    isLessThan(20)
}

fails {
    expect(13).isA<Int>().and {
        // introduces an assertion group block
        // all assertions are evaluated inside an assertion group block; for more details:
        // https://github.com/robstoll/atrium#define-single-assertions-or-assertion-groups
        // use `.and.` if you want fail fast behaviour

        isNoneOf(1, 2, 13) // fails
        isLessThan(10)     // still evaluated and included in the error report
    }
}

Return
An Expect for the current subject of the assertion.