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then and by Packages

then.AssertThat(t, actual, matcher)

The core assertion function. Evaluates the matcher against the actual value and calls t.Errorf with a human-readable message when it does not match.

then.AssertThat(t, "hello", is.EqualTo("world"))
Expected: value equal to <world>
     but: <hello>

Adding a reason with .Reason(...) prepends a message to the output:

then.AssertThat(t, "hello", is.EqualTo("world").Reason("greeting must match"))
greeting must match
Expected: value equal to <world>
     but: <hello>

Using .Reasonf(format, args...) allows a formatted reason string:

then.AssertThat(t, got, is.EqualTo(want).Reasonf("attempt %d failed", attempt))

then.Eventually(t, waitFor, tick, assertions)

Repeatedly runs the assertions function on a tick interval until all assertions pass or the waitFor timeout expires. Each run uses its own RecordingTestingT so failures do not immediately fail the outer test. If the timeout is reached the last set of failures is reported.

then.Eventually(t, 5*time.Second, time.Second, func(eventually gocrest.TestingT) {
    then.AssertThat(eventually, by.Channelling(channel), is.EqualTo(42))
})

Output when the timeout is reached before the assertion passes:

Eventually Failed after 5s:
Expected: value equal to <42>
     but: <0>

then.WithinFiveSeconds(t, assertions)

Shorthand for then.Eventually(t, 5*time.Second, time.Second, assertions).

then.WithinFiveSeconds(t, func(eventually gocrest.TestingT) {
    then.AssertThat(eventually, by.Channelling(channel), is.EqualTo("done"))
})

then.WithinTenSeconds(t, assertions)

Shorthand for then.Eventually(t, 10*time.Second, time.Second, assertions).

then.WithinTenSeconds(t, func(eventually gocrest.TestingT) {
    then.AssertThat(eventually, by.Channelling(channel), is.EqualTo("done"))
})

by.Channelling[T](channel chan T) T

Reads one value from the channel and returns it. Intended to be used as the actual argument inside then.Eventually.

ch := make(chan int, 1)
go func() { ch <- 99 }()

then.Eventually(t, 5*time.Second, time.Second, func(eventually gocrest.TestingT) {
    then.AssertThat(eventually, by.Channelling(ch), is.EqualTo(100))
})
Eventually Failed after 5s:
Expected: value equal to <100>
     but: <99>

by.Reading(reader io.Reader, len int) []byte

Reads up to len bytes from the reader and returns them as a byte slice. Intended to be used as the actual argument inside then.Eventually.

then.WithinFiveSeconds(t, func(eventually gocrest.TestingT) {
    then.AssertThat(eventually, by.Reading(reader, 5), is.EqualTo([]byte("hello")))
})
Eventually Failed after 5s:
Expected: value equal to <[104 105]>
     but: <[0]: expected <104>, got <0>>

by.Calling[K, T](fn func(T) K, value T) K

Calls fn(value) and returns the result. Use this to wrap a function call as the actual argument of an assertion.

double := func(n int) int { return n * 2 }
then.AssertThat(t, by.Calling(double, 3), is.EqualTo(7))
Expected: value equal to <7>
     but: <6>