func TestFilter(t *testing.T) {
evens := func(d stream.T) bool { return d.(int)%2 == 0 }
Convey("Given I have a context", t, func() {
context := rivers.NewContext()
Convey("And a stream of data", func() {
in, out := stream.New(2)
out <- 1
out <- 2
close(out)
Convey("When I apply the transformer to the stream", func() {
transformer := transformers.Filter(evens)
transformer.Attach(context)
transformed := transformer.Transform(in)
Convey("Then a transformed stream is returned", func() {
So(transformed.ReadAll(), ShouldResemble, []stream.T{2})
})
})
Convey("When I close the context", func() {
context.Close(stream.Done)
Convey("And I apply the transformer to the stream", func() {
transformer := transformers.Filter(evens)
transformer.Attach(context)
next := transformer.Transform(in)
Convey("Then no item is sent to the next stage", func() {
So(next.ReadAll(), ShouldBeEmpty)
})
})
})
})
})
}
func (pipeline *Pipeline) Filter(fn stream.PredicateFn) *Pipeline {
return pipeline.ApplyParallel(transformers.Filter(fn))
}