Turns fromJson into a Product constructor

The JsonObject forward declaration seems good enough.
No actual leakage of WinRT types
to be consistent with the production API.

storeapi/base/impl/WinMockContext.cpp

@@ -16,6 +16,7 @@
 #include <iterator>
 #include <sstream>
 #include <unordered_map>
+#include <utility>
 
 #include "WinRTHelpers.hpp"
 
@@ -35,9 +36,6 @@ namespace {
 IAsyncOperation<JsonObject> call(winrt::hstring relativePath,
                                  UrlParams const& params = {});
 
-/// Creates a product from a JsonObject containing the relevant information.
-WinMockContext::Product fromJson(JsonObject const& obj);
-
 /// Translates a textual representation of a purchase transaction result into an
 /// instance of the PurchaseStatus enum.
 StoreApi::PurchaseStatus translate(winrt::hstring const& purchaseStatus);
@@ -69,7 +67,7 @@ std::vector<WinMockContext::Product> WinMockContext::GetProducts(
   result.reserve(products.Size());
   for (const IJsonValue& product : products) {
     JsonObject p = product.GetObject();
-    result.emplace_back(fromJson(p));
+    result.emplace_back(WinMockContext::Product{p});
   }
 
   return result;
@@ -131,6 +129,22 @@ void WinMockContext::Product::PromptUserForPurchase(
           });
 }
 
+WinMockContext::Product::Product(JsonObject const& json)
+    : storeID{winrt::to_string(json.GetNamedString(L"StoreID"))},
+      title{winrt::to_string(json.GetNamedString(L"Title"))},
+      description{winrt::to_string(json.GetNamedString(L"Description"))},
+      productKind{winrt::to_string(json.GetNamedString(L"ProductKind"))},
+      expirationDate{},
+      isInUserCollection{json.GetNamedBoolean(L"IsInUserCollection")}
+
+{
+  std::chrono::system_clock::time_point tp{};
+  std::stringstream ss{
+      winrt::to_string(json.GetNamedString(L"ExpirationDate"))};
+  ss >> std::chrono::parse("%FT%T%Tz", tp);
+  expirationDate = tp;
+}
+
 namespace {
 // Returns the mock server endpoint address and port by reading the environment
 // variable UP4W_MS_STORE_MOCK_ENDPOINT or localhost:9 if the variable is unset.
@@ -177,20 +191,6 @@ IAsyncOperation<JsonObject> call(winrt::hstring relativePath,
   co_return JsonObject::Parse(contents);
 }
 
-WinMockContext::Product fromJson(JsonObject const& obj) {
-  std::chrono::system_clock::time_point tp{};
-  std::stringstream ss{winrt::to_string(obj.GetNamedString(L"ExpirationDate"))};
-  ss >> std::chrono::parse("%FT%T%Tz", tp);
-
-  return WinMockContext::Product{
-      winrt::to_string(obj.GetNamedString(L"StoreID")),
-      winrt::to_string(obj.GetNamedString(L"Title")),
-      winrt::to_string(obj.GetNamedString(L"Description")),
-      winrt::to_string(obj.GetNamedString(L"ProductKind")),
-      tp,
-      obj.GetNamedBoolean(L"IsInUserCollection")};
-}
-
 StoreApi::PurchaseStatus translate(winrt::hstring const& purchaseStatus) {
   if (purchaseStatus == L"Succeeded") {
     return PurchaseStatus::Succeeded;

storeapi/base/impl/WinMockContext.hpp

@@ -13,6 +13,10 @@
 
 #include "../Purchase.hpp"
 
+namespace winrt::Windows::Data::Json {
+class JsonObject;
+}
+
 namespace StoreApi::impl {
 
 class WinMockContext {
@@ -50,17 +54,10 @@ class WinMockContext {
     void PromptUserForPurchase(PurchaseCallback callback) const;
 
    public:
+    /// Creates a product from a JsonObject obtained from a call to the mock
+    /// server containing the relevant information.
+    explicit Product(winrt::Windows::Data::Json::JsonObject const& json);
     Product() = default;
-    Product(std::string&& storeID, std::string&& title,
-            std::string&& description, std::string&& productKind,
-            std::chrono::system_clock::time_point expirationDate,
-            bool isInUserCollection)
-        : storeID(std::move(storeID)),
-          title(std::move(title)),
-          description(std::move(description)),
-          productKind(std::move(productKind)),
-          expirationDate(std::move(expirationDate)),
-          isInUserCollection(isInUserCollection) {}
   };
 
   // Returns a collection of products matching the supplied [kinds] and [ids].