add test for Resolver.

tests/Resolver.cpp

@@ -0,0 +1,75 @@
+#include <AST/Resolver.h>
+#include <gtest/gtest.h>
+
+using namespace clice;
+
+namespace {
+
+struct ASTVisitor : public clang::RecursiveASTVisitor<ASTVisitor> {
+    clang::Sema& sema;
+    clang::QualType& result;
+    clang::ASTContext& context;
+
+    bool VisitTypeAliasDecl(clang::TypeAliasDecl* decl) {
+        if(decl->getName() == "result") {
+            auto type = decl->getUnderlyingType();
+            {
+                clang::Sema::CodeSynthesisContext context;
+                context.Kind = clang::Sema::CodeSynthesisContext::TemplateInstantiation;
+                context.Entity = decl;
+                context.TemplateArgs = nullptr;
+                sema.pushCodeSynthesisContext(context);
+            }
+            auto resolver = DependentNameResolver(sema, context);
+            result = resolver.resolve(type);
+        }
+        return true;
+    }
+};
+
+TEST(DependentNameResolver, resolve) {
+    std::vector<const char*> args{
+        "clang++",
+        "-std=c++20",
+        "main.cpp",
+        "-resource-dir=../build/lib/clang/20",
+    };
+
+    const char* code = R"(
+template <typename ...Ts>
+struct type_list {};
+
+template <typename T>
+struct A {
+    using type = type_list<T>;
+};
+
+template <typename X>
+struct test {
+    using result = typename A<X>::type;
+};
+)";
+
+    auto parsedAST = ParsedAST::build("main.cpp", code, args);
+    auto decl = parsedAST->context.getTranslationUnitDecl();
+
+    clang::QualType result;
+
+    ASTVisitor visitor{{}, parsedAST->sema, result, parsedAST->context};
+    visitor.TraverseDecl(decl);
+
+    {
+        auto TST = result->getAs<clang::TemplateSpecializationType>();
+        ASSERT_TRUE(TST);
+        ASSERT_EQ(TST->getTemplateName().getAsTemplateDecl()->getName(), "type_list");
+
+        auto args = TST->template_arguments();
+        ASSERT_EQ(args.size(), 1);
+        auto T = llvm::dyn_cast<clang::TemplateTypeParmType>(args[0].getAsType());
+        ASSERT_TRUE(T);
+        ASSERT_EQ(T->getDecl()->getName(), "X");
+    }
+}
+
+}  // namespace
+