Fix MakeRegexpArray handling empty strings

staging/src/k8s.io/kubectl/pkg/proxy/proxy_server.go

@@ -61,6 +61,9 @@ type FilterServer struct {
 
 // MakeRegexpArray splits a comma separated list of regexps into an array of Regexp objects.
 func MakeRegexpArray(str string) ([]*regexp.Regexp, error) {
+	if str == "" {
+		return []*regexp.Regexp{}, nil
+	}
 	parts := strings.Split(str, ",")
 	result := make([]*regexp.Regexp, len(parts))
 	for ix := range parts {

staging/src/k8s.io/kubectl/pkg/proxy/proxy_server_test.go

@@ -275,6 +275,28 @@ func TestAccept(t *testing.T) {
 			method:        "PUT",
 			expectAccept:  false,
 		},
+		{
+			name:          "test23",
+			acceptPaths:   DefaultPathAcceptRE,
+			rejectPaths:   DefaultPathRejectRE,
+			acceptHosts:   DefaultHostAcceptRE,
+			rejectMethods: DefaultMethodRejectRE,
+			path:          "/api/v1/namespaces/default/pods/somepod/exec",
+			host:          "localhost",
+			method:        "POST",
+			expectAccept:  false,
+		},
+		{
+			name:          "test24",
+			acceptPaths:   DefaultPathAcceptRE,
+			rejectPaths:   "",
+			acceptHosts:   DefaultHostAcceptRE,
+			rejectMethods: DefaultMethodRejectRE,
+			path:          "/api/v1/namespaces/default/pods/somepod/exec",
+			host:          "localhost",
+			method:        "POST",
+			expectAccept:  true,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {