testing: clarify T.Parallel() godoc wording

Fixes #18914.

Change-Id: Iec90d6aaa62595983db28b17794429f3c9a3dc36
Reviewed-on: https://go-review.googlesource.com/36272
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/testing/testing.go b/src/testing/testing.go
index 97c703d8ba0e1bc8fca60ffba8c43b8e0b46b9bc..d63d5d85a754fbc953029805f949cbbcaf2ac0b8 100644 (file)
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -569,7 +569,9 @@ func (c *common) Skipped() bool {
 }
 
 // Parallel signals that this test is to be run in parallel with (and only with)
-// other parallel tests.
+// other parallel tests. When a test is run multiple times due to use of
+// -test.count or -test.cpu, multiple instances of a single test never run in
+// parallel with each other.
 func (t *T) Parallel() {
        if t.isParallel {
                panic("testing: t.Parallel called multiple times")