мой main_test.go для задачи E https://contest.yandex.ru/contest/17728

main_test.go

package main

import (
	"log"
	"math/rand"
	"runtime"
	"sync"
	"testing"
	"time"
)

func init() {
	log.Println("GOMAXPROCS was", runtime.GOMAXPROCS(0))
	runtime.GOMAXPROCS(1)
}

func TestNil(t *testing.T) {
	repeats := -999
	var in1 chan int
	var in2 chan int
	var out chan int
	log.Println("Run Merge2Channels")
	Merge2Channels(fRandomSpeed, in1, in2, out, repeats)
}

func TestMerge2Channels3TimesSameChannelsFillInAfterRun(t *testing.T) {
	rand.Seed(time.Now().UnixNano())
	// repeats := rand.Intn(400)
	repeats := 999999
	log.Printf("Repeats=%d", repeats)
	in1 := make(chan int, repeats)
	in2 := make(chan int, repeats)
	out := make(chan int, repeats)
	log.Println("Run Merge2Channels 2 times with half of N")
	Merge2Channels(fRandomSpeed, in1, in2, out, repeats/3)
	Merge2Channels(fRandomSpeed, in1, in2, out, repeats/3)
	Merge2Channels(fRandomSpeed, in1, in2, out, repeats/3)
	results := make([]int, repeats)

	go func() {
		for i := 1; i < repeats+1; i++ {
			i1 := rand.Intn(200)
			i2 := rand.Intn(200)
			// to avoid data race in next range
			results[i-1] = fFast(i1) + fFast(i2)
			in1 <- i1
			in2 <- i2
		}
		log.Println("Sent all inputs, closing channel")
		close(in1)
		close(in2)
	}()
	log.Println("Reading through out channel")
	for i := 0; i < repeats; i++ {
		got, ok := <-out
		if !ok {
			t.Fatal("out channel is closed!")
		}
		if results[i] != got {
			t.Errorf("got %d, want %d", got, results[i])
		}
		//log.Println("result =", results[i])
		//log.Println("out =", got)
	}
	log.Println("Got all results, closing out channel")
	//close(out)
	// log.Println("results =", results)
}

func TestMerge2ChannelsNTimesDefferentChannelsFillInBeforeRun(t *testing.T) {
	rand.Seed(time.Now().UnixNano())
	repeats := 10000
	log.Printf("Repeats=%d", repeats)
	runTimes := 100
	//done := make(chan struct{}, runTimes)
	var wg sync.WaitGroup

	for r := 0; r < runTimes; r++ {
		wg.Add(1)
		rr := r
		go func() {
			in1 := make(chan int, repeats*2)
			in2 := make(chan int, repeats*2)
			out := make(chan int, repeats*2)

			results := make([]int, repeats)

			for i := 1; i < repeats+1; i++ {
				in1 <- i
				in2 <- i
				results[i-1] = fFast(i) * 2
				//log.Println("Wrote input", rr, i)
			}
			// add extra input
			for i := repeats + 1; i < repeats*2+1; i++ {
				in1 <- 1
				in2 <- 1
			}
			log.Println("Run Merge2Channels")
			Merge2Channels(fFast, in1, in2, out, repeats)
			go func(wg *sync.WaitGroup) {
				log.Println("Reading through out channel", rr)
				for i := 0; i < repeats; i++ {
					v := results[i]
					r := <-out
					if v != r {
						t.Errorf("got %d, want %d", r, v)
					}
				}
				log.Println("Done reading through out channel", rr)
				wg.Done()
				//done <- struct{}{}
			}(&wg)
		}()

	}
	wg.Wait()
	/*for i := 0; i < runTimes; i++ {
		<-done
	}*/
}

func fFast(n int) int {
	return n + n
}

func fRandomSpeed(n int) int {
	time.Sleep(time.Duration(rand.Int31n(500)) * time.Millisecond)
	return fFast(n)
}

func fSlow(n int) int {
	time.Sleep(1000 * time.Millisecond)
	return fFast(n)
}

func TestNonBlocking(t *testing.T) {
	capacity := 100
	portion := capacity / 10
	ch1 := make(chan int, capacity)
	ch2 := make(chan int, capacity)
	chOut := make(chan int, capacity)

	// fill only portion in case if function blocks on channels read
	for i := 0; i < portion; i++ {
		ch1 <- i
		ch2 <- i
	}

	done := make(chan struct{})

	go func() {
		Merge2Channels(fSlow, ch1, ch2, chOut, capacity)
		close(done)
	}()

	select {
	case <-done:
		close(ch1)
		close(ch2)
		//close(chOut)
		return
	case <-time.After(time.Millisecond * 100):
		t.Fatal("Function should be non-blocking")
	}
}

//check for reading extra input
//check for returning extra output
func TestMerge2ChannelsExtraData(t *testing.T) {
	capacity := 100
	portion := capacity / 2

	ch1 := make(chan int, capacity)
	ch2 := make(chan int, capacity)
	chOut := make(chan int, capacity)
	results := make([]int, capacity)

	i := 0
	for i < capacity {
		ch1 <- i + 42
		ch2 <- i * 42
		results[i] = fFast(i+42) + fFast(i*42)
		i++
	}

	done := make(chan struct{})

	go func() {
		Merge2Channels(fSlow, ch1, ch2, chOut, portion)
		close(done)
	}()

	<-done

	i = 0
	for i < portion {
		ans, ok := <-chOut
		if !ok {
			t.Fatal("Output channel should not be closed")
		}
		if ans != results[i] {
			t.Fatalf("Got %d from output channel, should be %d", ans, results[i])
		}
		i++
	}

	if len(ch1) != capacity-portion {
		t.Fatalf("First channel has %d numbers in it, should have %d", len(ch1), capacity-portion)
	}
	if len(ch2) != capacity-portion {
		t.Fatalf("Second channel has %d numbers in it, should have %d", len(ch2), capacity-portion)
	}
	if len(chOut) != 0 {
		t.Fatalf("Output channel has %d numbers in it, should have %d", len(chOut), 0)
	}
}