Check that all models can be instantiated

include/teqp/filesystem.hpp

+#pragma once
+
+#include <filesystem>
+
+/** Find all files in a given folder that match the specified file extension
+ *  The extension should be specified with the period, as in ".json"
+ */
+static auto get_files_in_folder(const std::string& folder, const std::string& extension) 
+{
+    std::vector<std::filesystem::path> files;
+    for (auto const& dir_entry : std::filesystem::directory_iterator{ folder }) {
+        auto path = dir_entry.path();
+        if (path.extension() == extension) {
+            files.push_back(path.filename());
+        }
+    }
+    return files;
+}
\ No newline at end of file

src/tests/catch_test_multifluid.cxx

@@ -2,6 +2,8 @@
 
 #include "teqp/models/multifluid.hpp"
 #include "teqp/algorithms/critical_tracing.hpp"
+#include "teqp/filesystem.hpp"
+
 
 TEST_CASE("Confirm failure for missing files","[multifluid]") {
     CHECK_THROWS(build_multifluid_model({ "BADFLUID" }, "IMPOSSIBLE PATH", "IMPOSSIBLE PATH.json"));
@@ -38,4 +40,13 @@ TEST_CASE("Trace critical locus for nitrogen + ethane", "[crit],[multifluid]")
         CHECK(j.size() > 3);
         auto tic1 = std::chrono::steady_clock::now();
     }
+}
+
+TEST_CASE("Check that all models can be instantiated", "[multifluid],[all]"){
+    std::string root = "../mycp";
+    for (auto filename : get_files_in_folder(root + "/dev/fluids", ".json")) {
+        auto stem = filename.stem().string(); // filename without the .json
+        if (stem == "Methanol") { continue; }
+        auto model = build_multifluid_model({ stem }, root, root + "/dev/mixtures/mixture_binary_pairs.json");
+    }
 }
\ No newline at end of file