func TestZipperBy(t *testing.T) {
adder := func(a, b stream.T) stream.T {
return a.(int) + b.(int)
}
Convey("Given I have a context", t, func() {
context := rivers.NewContext()
Convey("And a stream of data", func() {
in1, out1 := stream.New(2)
out1 <- 1
out1 <- 2
close(out1)
in2, out2 := stream.New(4)
out2 <- 3
out2 <- 4
out2 <- 5
out2 <- 6
close(out2)
Convey("When I apply the combiner to the streams", func() {
combiner := combiners.ZipBy(adder)
combiner.Attach(context)
combined := combiner.Combine(in1, in2)
Convey("Then a transformed stream is returned", func() {
So(combined.ReadAll(), ShouldResemble, []stream.T{4, 6, 5, 6})
})
})
Convey("When I close the context", func() {
context.Close(stream.Done)
Convey("And I apply the transformer to the stream", func() {
combiner := combiners.ZipBy(adder)
combiner.Attach(context)
combined := combiner.Combine(in1, in2)
Convey("Then no item is sent to the next stage", func() {
So(combined.ReadAll(), ShouldBeEmpty)
})
})
})
})
})
}
func (pipeline *Pipeline) ZipBy(fn stream.ReduceFn, pipelines ...*Pipeline) *Pipeline {
return pipeline.Combine(combiners.ZipBy(fn), pipelines)
}