channel tests: added a couple of tests with closed channels

R=rsc
CC=golang-dev
https://golang.org/cl/1774047

diff --git a/test/chan/select3.go b/test/chan/select3.go
index f429f9e8f905ba29d2222c9f28d9a0f4c81aab9e..d4f7ebcec0896cfc6325d268def373fc3ce606b4 100644 (file)
--- a/test/chan/select3.go
+++ b/test/chan/select3.go
@@ -25,7 +25,7 @@ func testPanic(signal string, f func()) {
        defer func() {
                s := never
                if recover() != nil {
-                       s = always  // f panicked
+                       s = always // f panicked
                }
                if s != signal {
                        panic(signal + " panic")
@@ -55,6 +55,8 @@ func testBlock(signal string, f func()) {
 func main() {
        const async = 1 // asynchronous channels
        var nilch chan int
+       closedch := make(chan int)
+       close(closedch)
 
        // sending/receiving from a nil channel outside a select panics
        testPanic(always, func() {
@@ -86,6 +88,24 @@ func main() {
                ch <- 7
        })
 
+       // receiving (a small number of times) from a closed channel never blocks
+       testBlock(never, func() {
+               for i := 0; i < 10; i++ {
+                       if <-closedch != 0 {
+                               panic("expected zero value when reading from closed channel")
+                       }
+               }
+       })
+
+       // sending (a small number of times) to a closed channel is not specified
+       // but the current implementation doesn't block: test that different
+       // implementations behave the same
+       testBlock(never, func() {
+               for i := 0; i < 10; i++ {
+                       closedch <- 7
+               }
+       })
+
        // receiving from a non-ready channel always blocks
        testBlock(always, func() {
                ch := make(chan int)
@@ -173,4 +193,16 @@ func main() {
                        unreachable()
                }
        })
+
+       // selects with closed channels don't block
+       testBlock(never, func() {
+               select {
+               case <-closedch:
+               }
+       })
+       testBlock(never, func() {
+               select {
+               case closedch <- 7:
+               }
+       })
 }