fix: conform to url specification for set

Author: anonrig

src/url_search_params.cpp

@@ -34,12 +34,17 @@ void url_search_params::sort() {
 
 void url_search_params::set(const std::string_view key,
                             const std::string_view value) {
-  params.erase(
-      std::remove_if(params.begin(), params.end(),
-                     [&key](auto &param) { return param.first == key; }),
-      params.end());
+  const auto find = [&key](auto &param) { return param.first == key; };
+
+  auto it = std::find_if(params.begin(), params.end(), find);
 
-  params.emplace_back(key, value);
+  if (it == params.end()) {
+    params.emplace_back(key, value);
+  } else {
+    it->second = value;
+    params.erase(std::remove_if(std::next(it), params.end(), find),
+                 params.end());
+  }
 }
 
 std::string url_search_params::to_string() {

tests/url_search_params.cpp

@@ -29,6 +29,18 @@ TEST(url_search_params, set) {
   search_params.set("key1", "hello");
   ASSERT_EQ(search_params.size(), 1);
   ASSERT_EQ(search_params.to_string(), "key1=hello");
+
+  // reset to initial state
+  search_params.remove("key1");
+  search_params.append("key1", "value1");
+  search_params.append("key1", "value2");
+  search_params.append("key2", "value1");
+  search_params.set("key1", "value3");
+  ASSERT_EQ(search_params.size(), 2);
+  ASSERT_EQ(search_params.to_string(), "key1=value3&key2=value1");
+  search_params.set("key1", "value4");
+  ASSERT_EQ(search_params.to_string(), "key1=value4&key2=value1");
+
   SUCCEED();
 }