unix, windows: use ^TestName$ regular pattern for invoking a single test

For reasons motivated in the commit message of CL 524948.

Change-Id: I0085411f30a77634962239ee36d15e7b6ef893ef
Reviewed-on: https://go-review.googlesource.com/c/sys/+/525618
Auto-Submit: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: dmitshur

unix/syscall_zos_test.go

@@ -757,7 +757,7 @@ func TestFlock(t *testing.T) {
 		if err != nil {
 			t.Fatalf("Flock: %s", err.Error())
 		}
-		cmd := exec.Command(os.Args[0], "-test.run=TestFlock", f.Name())
+		cmd := exec.Command(os.Args[0], "-test.run=^TestFlock$", f.Name())
 		cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
 		out, err := cmd.CombinedOutput()
 		if len(out) > 0 || err != nil {

windows/svc/svc_test.go

@@ -182,7 +182,7 @@ func TestIsWindowsServiceWhenParentExits(t *testing.T) {
 		// in parent process
 
 		// Start the child and exit quickly.
-		child := exec.Command(os.Args[0], "-test.run=TestIsWindowsServiceWhenParentExits")
+		child := exec.Command(os.Args[0], "-test.run=^TestIsWindowsServiceWhenParentExits$")
 		child.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=child")
 		err := child.Start()
 		if err != nil {
@@ -221,7 +221,7 @@ func TestIsWindowsServiceWhenParentExits(t *testing.T) {
 	for i := 0; i < 10; i++ {
 		childDumpPath := filepath.Join(t.TempDir(), "issvc.txt")
 
-		parent := exec.Command(os.Args[0], "-test.run=TestIsWindowsServiceWhenParentExits")
+		parent := exec.Command(os.Args[0], "-test.run=^TestIsWindowsServiceWhenParentExits$")
 		parent.Env = append(os.Environ(),
 			"GO_WANT_HELPER_PROCESS=parent",
 			"GO_WANT_HELPER_PROCESS_FILE="+childDumpPath)