runtime: skip TestLockOSThreadAvoidsStatePropagation if one can't unshare

This change splits a testprog out of TestLockOSThreadExit and makes it
its own test. Then, this change makes the testprog exit prematurely with
a special message if unshare fails with EPERM because not all of the
builders allow the user to call the unshare syscall.

Also, do some minor cleanup on the TestLockOSThread* tests.

Fixes #29366.

Change-Id: Id8a9f6c4b16e26af92ed2916b90b0249ba226dbe
Reviewed-on: https://go-review.googlesource.com/c/155437
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 13 insertions, 8 deletions

diff --git a/src/runtime/proc_test.go b/src/runtime/proc_test.go
index e6947d5849..1715324aa0 100644
--- a/src/runtime/proc_test.go
+++ b/src/runtime/proc_test.go
@@ -885,23 +885,28 @@ func TestLockOSThreadNesting(t *testing.T) {
 
 func TestLockOSThreadExit(t *testing.T) {
 	testLockOSThreadExit(t, "testprog")
-
-	want := "OK\n"
-	output := runTestProg(t, "testprog", "LockOSThreadAvoidsStatePropagation", "GOMAXPROCS=1")
-	if output != want {
-		t.Errorf("want %s, got %s\n", want, output)
-	}
 }
 
 func testLockOSThreadExit(t *testing.T, prog string) {
 	output := runTestProg(t, prog, "LockOSThreadMain", "GOMAXPROCS=1")
 	want := "OK\n"
 	if output != want {
-		t.Errorf("want %s, got %s\n", want, output)
+		t.Errorf("want %q, got %q", want, output)
 	}
 
 	output = runTestProg(t, prog, "LockOSThreadAlt")
 	if output != want {
-		t.Errorf("want %s, got %s\n", want, output)
+		t.Errorf("want %q, got %q", want, output)
+	}
+}
+
+func TestLockOSThreadAvoidsStatePropagation(t *testing.T) {
+	want := "OK\n"
+	skip := "unshare not permitted\n"
+	output := runTestProg(t, "testprog", "LockOSThreadAvoidsStatePropagation", "GOMAXPROCS=1")
+	if output == skip {
+		t.Skip("unshare syscall not permitted on this system")
+	} else if output != want {
+		t.Errorf("want %q, got %q", want, output)
 	}
 }