runtime/pprof: make TestBlockMutexProfileInlineExpansion stricter

While working on CL 611241 and CL 616375, I introduced a bug that wasn't
caught by any test. CL 611241 added more inline expansion at sample time
for block/mutex profile stacks collected via frame pointer unwinding.
CL 616375 then changed how inline expansion for those stacks is done at
reporting time. So some frames passed through multiple rounds of inline
expansion, and this lead to duplicate stack frames in some cases. The
stacks from TestBlockMutexProfileInlineExpansion looked like

	sync.(*Mutex).Unlock
	runtime/pprof.inlineF
	runtime/pprof.inlineE
	runtime/pprof.inlineD
	runtime/pprof.inlineD
	runtime.goexit

after those two CLs, and in particular after CL 616375. Note the extra
inlineD frame. The test didn't catch that since it was only looking for
a few frames in the stacks rather than checking the entire stacks.

This CL makes that test stricter by checking the entire expected stacks
rather than just a portion of the stacks.

Change-Id: I0acc739d826586e9a63a081bb98ef512d72cdc9a
Reviewed-on: https://go-review.googlesource.com/c/go/+/617235
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

src/runtime/pprof/pprof_test.go

@@ -2727,38 +2727,38 @@ func TestBlockMutexProfileInlineExpansion(t *testing.T) {
 	wg.Wait()
 
 	tcs := []struct {
-		Name     string
-		Collect  func([]runtime.BlockProfileRecord) (int, bool)
-		SubStack string
+		Name    string
+		Collect func([]runtime.BlockProfileRecord) (int, bool)
+		Stack   string
 	}{
 		{
 			Name:    "mutex",
 			Collect: runtime.MutexProfile,
-			SubStack: `sync.(*Mutex).Unlock
+			Stack: `sync.(*Mutex).Unlock
 runtime/pprof.inlineF
 runtime/pprof.inlineE
-runtime/pprof.inlineD`,
+runtime/pprof.inlineD
+runtime.goexit`,
 		},
 		{
 			Name:    "block",
 			Collect: runtime.BlockProfile,
-			SubStack: `sync.(*Mutex).Lock
+			Stack: `sync.(*Mutex).Lock
 runtime/pprof.inlineC
 runtime/pprof.inlineB
-runtime/pprof.inlineA`,
+runtime/pprof.inlineA
+runtime.goexit`,
 		},
 	}
 
 	for _, tc := range tcs {
 		t.Run(tc.Name, func(t *testing.T) {
 			stacks := getProfileStacks(tc.Collect, false)
-			for _, s := range stacks {
-				if strings.Contains(s, tc.SubStack) {
-					return
-				}
+			if slices.Contains(stacks, tc.Stack) {
+				return
 			}
 			t.Error("did not see expected stack")
-			t.Logf("wanted:\n%s", tc.SubStack)
+			t.Logf("wanted:\n%s", tc.Stack)
 			t.Logf("got: %s", stacks)
 		})
 	}