net: add test that TCP Close unblocks blocked Reads

I guess this was fixed at some point. Remove a skipped test in
net/http and add an explicit test in net.

Fixes #17695

Change-Id: Idb9f3e236b726bb45098474b830c95c1fce57529
Reviewed-on: https://go-review.googlesource.com/33242
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/http/serve_test.go

@@ -4907,9 +4907,6 @@ func get(t *testing.T, c *Client, url string) string {
 // Tests that calls to Server.SetKeepAlivesEnabled(false) closes any
 // currently-open connections.
 func TestServerSetKeepAlivesEnabledClosesConns(t *testing.T) {
-	if runtime.GOOS == "nacl" {
-		t.Skip("skipping on nacl; see golang.org/issue/17695")
-	}
 	setParallel(t)
 	defer afterTest(t)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {

src/net/net_test.go

@@ -497,3 +497,22 @@ func TestReadTimeoutUnblocksRead(t *testing.T) {
 	}
 	withTCPConnPair(t, client, server)
 }
+
+// Issue 17695: verify that a blocked Read is woken up by a Close.
+func TestCloseUnblocksRead(t *testing.T) {
+	t.Parallel()
+	server := func(cs *TCPConn) error {
+		// Give the client time to get stuck in a Read:
+		time.Sleep(20 * time.Millisecond)
+		cs.Close()
+		return nil
+	}
+	client := func(ss *TCPConn) error {
+		n, err := ss.Read([]byte{0})
+		if n != 0 || err != io.EOF {
+			return fmt.Errorf("Read = %v, %v; want 0, EOF", n, err)
+		}
+		return nil
+	}
+	withTCPConnPair(t, client, server)
+}