cmd/vet: add subtestnames analyzer; fix all existing violations

Add a new vet analyzer that checks t.Run subtest names don't contain
characters requiring quoting when re-running via "go test -run". This
enforces the style guide rule: don't use spaces or punctuation in
subtest names.

The analyzer flags:
- Direct t.Run calls with string literal names containing spaces,
  regex metacharacters, quotes, or other problematic characters
- Table-driven t.Run(tt.name, ...) calls where tt ranges over a
  slice/map literal with bad name field values

Also fix all 978 existing violations across 81 test files, replacing
spaces with hyphens and shortening long sentence-like names to concise
hyphenated forms.

Updates #19242

Change-Id: Ib0ad96a111bd8e764582d1d4902fe2599454ab65
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

drive/driveimpl/dirfs/dirfs_test.go

@@ -29,7 +29,7 @@ func TestStat(t *testing.T) {
 		err      error
 	}{
 		{
-			label: "root folder",
+			label: "root-folder",
 			name:  "",
 			expected: &shared.StaticFileInfo{
 				Named:      "",
@@ -40,7 +40,7 @@ func TestStat(t *testing.T) {
 			},
 		},
 		{
-			label: "static root folder",
+			label: "static-root-folder",
 			name:  "/domain",
 			expected: &shared.StaticFileInfo{
 				Named:      "domain",
@@ -73,7 +73,7 @@ func TestStat(t *testing.T) {
 			},
 		},
 		{
-			label: "non-existent remote",
+			label: "non-existent-remote",
 			name:  "remote3",
 			err:   os.ErrNotExist,
 		},
@@ -108,7 +108,7 @@ func TestListDir(t *testing.T) {
 		err      error
 	}{
 		{
-			label: "root folder",
+			label: "root-folder",
 			name:  "",
 			expected: []fs.FileInfo{
 				&shared.StaticFileInfo{
@@ -121,7 +121,7 @@ func TestListDir(t *testing.T) {
 			},
 		},
 		{
-			label: "static root folder",
+			label: "static-root-folder",
 			name:  "/domain",
 			expected: []fs.FileInfo{
 				&shared.StaticFileInfo{
@@ -189,19 +189,19 @@ func TestMkdir(t *testing.T) {
 		err   error
 	}{
 		{
-			label: "attempt to create root folder",
+			label: "create-root-folder",
 			name:  "/",
 		},
 		{
-			label: "attempt to create static root folder",
+			label: "create-static-root-folder",
 			name:  "/domain",
 		},
 		{
-			label: "attempt to create remote",
+			label: "create-remote",
 			name:  "/domain/remote1",
 		},
 		{
-			label: "attempt to create non-existent remote",
+			label: "create-non-existent-remote",
 			name:  "/domain/remote3",
 			err:   os.ErrPermission,
 		},
@@ -231,7 +231,7 @@ func TestRemoveAll(t *testing.T) {
 		err   error
 	}{
 		{
-			label: "attempt to remove root folder",
+			label: "remove-root-folder",
 			name:  "/",
 			err:   os.ErrPermission,
 		},
@@ -258,7 +258,7 @@ func TestRename(t *testing.T) {
 		err     error
 	}{
 		{
-			label:   "attempt to move root folder",
+			label:   "move-root-folder",
 			oldName: "/",
 			newName: "/domain/remote2/copy.txt",
 			err:     os.ErrPermission,

drive/driveimpl/drive_test.go

@@ -156,27 +156,27 @@ func TestMissingPaths(t *testing.T) {
 		wantStatus int
 	}{
 		{
-			name:       "empty path",
+			name:       "empty-path",
 			path:       "",
 			wantStatus: http.StatusForbidden,
 		},
 		{
-			name:       "single slash",
+			name:       "single-slash",
 			path:       "/",
 			wantStatus: http.StatusForbidden,
 		},
 		{
-			name:       "only token",
+			name:       "only-token",
 			path:       "/" + secretToken,
 			wantStatus: http.StatusBadRequest,
 		},
 		{
-			name:       "token with trailing slash",
+			name:       "token-trailing-slash",
 			path:       "/" + secretToken + "/",
 			wantStatus: http.StatusBadRequest,
 		},
 		{
-			name:       "token and invalid share",
+			name:       "token-invalid-share",
 			path:       "/" + secretToken + "/nonexistentshare",
 			wantStatus: http.StatusNotFound,
 		},