QueryString handles null inputs

src/QueryString.cpp

@@ -7,7 +7,7 @@
  */
 QueryString::QueryString(const char* query) : n(0)
 {
-  if (query[0] == '\0') return;
+  if (query == nullptr || query[0] == '\0') return;
 
   // create buffer
   buffer_length = urlenc::decoded_length(query) + 2;
@@ -116,6 +116,8 @@ size_t QueryString::str_count_fields(const char* query)
 
 QueryString::~QueryString()
 {
-  free(buffer);
-  free(fields);
+  if (n) {
+    free(buffer);
+    free(fields);
+  }
 }

test/test_QueryString.cpp

@@ -91,3 +91,15 @@ TEST_CASE("str_count_fields", "[QueryString][str_count_fields]")
   CHECK(QueryString::str_count_fields("foo=bar&baz=qux") == 2);
   CHECK(QueryString::str_count_fields("foo&bar&foo&bar") == 4);
 }
+
+TEST_CASE("empty string", "[QueryString][QueryString-empty]")
+{
+  QueryString qs("");
+  CHECK(qs.count() == 0);
+}
+
+TEST_CASE("constructor with nullptr", "[QueryString-nullptr]")
+{
+  QueryString qs(nullptr);
+  CHECK(qs.count() == 0);
+}