🧪 test: add LSP json fixtures and provider suite

lsp-server/test/test_provider/fixtures.cppm

@@ -0,0 +1,63 @@
+module;
+
+export module lsp.test.provider.fixtures;
+
+import std;
+
+export namespace lsp::test::provider
+{
+    inline std::string& ExecutablePathStorage()
+    {
+        static std::string value;
+        return value;
+    }
+
+    inline void SetExecutablePath(std::string value)
+    {
+        ExecutablePathStorage() = std::move(value);
+    }
+
+    inline const std::string& ExecutablePath()
+    {
+        return ExecutablePathStorage();
+    }
+
+    inline std::filesystem::path FixturesRoot()
+    {
+        return std::filesystem::path(__FILE__).parent_path() / "fixtures";
+    }
+
+    inline std::filesystem::path FixturePath(const std::string& name)
+    {
+        return FixturesRoot() / name;
+    }
+
+    inline std::string ToUri(const std::filesystem::path& path)
+    {
+        auto absolute = std::filesystem::absolute(path).generic_string();
+#ifdef _WIN32
+        std::string normalized;
+        normalized.reserve(absolute.size());
+        for (char ch : absolute)
+        {
+            normalized.push_back(ch == '\\' ? '/' : ch);
+        }
+        absolute = normalized;
+#endif
+        if (!absolute.empty() && absolute.front() != '/')
+        {
+            absolute.insert(absolute.begin(), '/');
+        }
+        return "file://" + absolute;
+    }
+
+    inline std::string ReadTextFile(const std::filesystem::path& path)
+    {
+        std::ifstream file(path, std::ios::binary);
+        if (!file.is_open())
+        {
+            throw std::runtime_error("Failed to open fixture: " + path.string());
+        }
+        return std::string((std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>());
+    }
+}