all: use ^TestName$ regular pattern for invoking a single test

Use ^ and $ in the -run flag regular expression value when the intention
is to invoke a single named test. This removes the reliance on there not
being another similarly named test to achieve the intended result.

In particular, package syscall has tests named TestUnshareMountNameSpace
and TestUnshareMountNameSpaceChroot that both trigger themselves setting
GO_WANT_HELPER_PROCESS=1 to run alternate code in a helper process. As a
consequence of overlap in their test names, the former was inadvertently
triggering one too many helpers.

Spotted while reviewing CL 525196. Apply the same change in other places
to make it easier for code readers to see that said tests aren't running
extraneous tests. The unlikely cases of -run=TestSomething intentionally
being used to run all tests that have the TestSomething substring in the
name can be better written as -run=^.*TestSomething.*$ or with a comment
so it is clear it wasn't an oversight.

Change-Id: Iba208aba3998acdbf8c6708e5d23ab88938bfc1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/524948
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Kirill Kolyshkin <kolyshkin@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

4 files changed, 5 insertions, 5 deletions

diff --git a/src/internal/cpu/cpu_test.go b/src/internal/cpu/cpu_test.go
index b8c74f2e9c..a6fe7f77f3 100644
--- a/src/internal/cpu/cpu_test.go
+++ b/src/internal/cpu/cpu_test.go
@@ -30,7 +30,7 @@ func runDebugOptionsTest(t *testing.T, test string, options string) {
 
 	env := "GODEBUG=" + options
 
-	cmd := exec.Command(os.Args[0], "-test.run="+test)
+	cmd := exec.Command(os.Args[0], "-test.run=^"+test+"$")
 	cmd.Env = append(cmd.Env, env)
 
 	output, err := cmd.CombinedOutput()
diff --git a/src/internal/godebug/godebug_test.go b/src/internal/godebug/godebug_test.go
index 8e46283ada..ed8e93d453 100644
--- a/src/internal/godebug/godebug_test.go
+++ b/src/internal/godebug/godebug_test.go
@@ -72,7 +72,7 @@ func TestMetrics(t *testing.T) {
 
 func TestCmdBisect(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
-	out, err := exec.Command("go", "run", "cmd/vendor/golang.org/x/tools/cmd/bisect", "GODEBUG=buggy=1#PATTERN", os.Args[0], "-test.run=BisectTestCase").CombinedOutput()
+	out, err := exec.Command("go", "run", "cmd/vendor/golang.org/x/tools/cmd/bisect", "GODEBUG=buggy=1#PATTERN", os.Args[0], "-test.run=^TestBisectTestCase$").CombinedOutput()
 	if err != nil {
 		t.Fatalf("exec bisect: %v\n%s", err, out)
 	}
@@ -101,7 +101,7 @@ func TestCmdBisect(t *testing.T) {
 
 // This test does nothing by itself, but you can run
 //
-//	bisect 'GODEBUG=buggy=1#PATTERN' go test -run=BisectTestCase
+//	bisect 'GODEBUG=buggy=1#PATTERN' go test -run='^TestBisectTestCase$'
 //
 // to see that the GODEBUG bisect support is working.
 // TestCmdBisect above does exactly that.
diff --git a/src/internal/platform/supported.go b/src/internal/platform/supported.go
index b1e550ef32..4589903550 100644
--- a/src/internal/platform/supported.go
+++ b/src/internal/platform/supported.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:generate go test . -run=TestGenerated -fix
+//go:generate go test . -run=^TestGenerated$ -fix
 
 package platform
 
diff --git a/src/internal/syscall/windows/exec_windows_test.go b/src/internal/syscall/windows/exec_windows_test.go
index 3311da5474..72550b5a84 100644
--- a/src/internal/syscall/windows/exec_windows_test.go
+++ b/src/internal/syscall/windows/exec_windows_test.go
@@ -29,7 +29,7 @@ func TestRunAtLowIntegrity(t *testing.T) {
 		return
 	}
 
-	cmd := exec.Command(os.Args[0], "-test.run=TestRunAtLowIntegrity", "--")
+	cmd := exec.Command(os.Args[0], "-test.run=^TestRunAtLowIntegrity$", "--")
 	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
 
 	token, err := getIntegrityLevelToken(sidWilLow)