testing: disable tests that cause a hang on some platforms

plan9, nacl, and netbsd to be precise.

Only the first test causes a hang, but just to be sure.

Change-Id: I400bb356ee2a0cf12c8666c95af79c924d1629aa
Reviewed-on: https://go-review.googlesource.com/20839
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/testing/sub_test.go

@@ -178,57 +178,6 @@ func TestTRun(t *T) {
 				t.Errorf("count was %d; want 4", count)
 			}
 		},
-	}, {
-		desc:   "run no more than *parallel tests concurrently",
-		ok:     true,
-		maxPar: 4,
-		f: func(t *T) {
-			max := 0
-			in := make(chan int)
-			out := make(chan int)
-			ctx := t.context
-			t.Run("wait", func(t *T) {
-				t.Run("controller", func(t *T) {
-					// Verify sequential tests don't skew counts.
-					t.Run("seq1", func(t *T) {})
-					t.Run("seq2", func(t *T) {})
-					t.Run("seq3", func(t *T) {})
-					t.Parallel()
-					for i := 0; i < 80; i++ {
-						ctx.mu.Lock()
-						if ctx.running > max {
-							max = ctx.running
-						}
-						ctx.mu.Unlock()
-						<-in
-						// force a minimum to avoid a race, although it works
-						// without it.
-						if i >= ctx.maxParallel-2 { // max - this - 1
-							out <- i
-						}
-					}
-					close(out)
-				})
-				// Ensure we don't exceed the maximum even with nested parallelism.
-				for i := 0; i < 2; i++ {
-					t.Run("", func(t *T) {
-						t.Parallel()
-						for j := 0; j < 40; j++ {
-							t.Run("", func(t *T) {
-								t.Run("seq1", func(t *T) {})
-								t.Run("seq2", func(t *T) {})
-								t.Parallel()
-								in <- j
-								<-out
-							})
-						}
-					})
-				}
-			})
-			if max != ctx.maxParallel {
-				realTest.Errorf("max: got %d; want: %d", max, ctx.maxParallel)
-			}
-		},
 	}, {
 		desc: "alternate sequential and parallel",
 		// Sequential tests should partake in the counting of running threads.
@@ -249,7 +198,7 @@ func TestTRun(t *T) {
 			})
 		},
 	}, {
-		desc: "alternate sequential and parallel",
+		desc: "alternate sequential and parallel 2",
 		// Sequential tests should partake in the counting of running threads.
 		// Otherwise, if one runs parallel subtests in sequential tests that are
 		// itself subtests of parallel tests, the counts can get askew.
@@ -298,7 +247,6 @@ func TestTRun(t *T) {
 									t.Run("d4", func(t *T) {})
 								})
 							}
-
 						})
 					}
 				})