diff --git a/apps/openmw_test_suite/mwscript/test_scripts.cpp b/apps/openmw_test_suite/mwscript/test_scripts.cpp
index d019244275..fcb4c3de5d 100644
--- a/apps/openmw_test_suite/mwscript/test_scripts.cpp
+++ b/apps/openmw_test_suite/mwscript/test_scripts.cpp
@@ -1,140 +1,370 @@
-#include <gtest/gtest.h>
-
-#include <optional>
-#include <sstream>
-#include <string>
-#include <utility>
-#include <vector>
-
-#include <components/compiler/context.hpp>
-#include <components/compiler/errorhandler.hpp>
-#include <components/compiler/exception.hpp>
-#include <components/compiler/fileparser.hpp>
-#include <components/compiler/scanner.hpp>
-
-#include <components/interpreter/interpreter.hpp>
-
-namespace
-{
-    class TestCompilerContext : public Compiler::Context
-    {
-    public:
-        bool canDeclareLocals() const override { return true; }
-        char getGlobalType(const std::string& name) const override { return ' '; }
-        std::pair<char, bool> getMemberType(const std::string& name, const std::string& id) const override { return {' ', false}; }
-        bool isId(const std::string& name) const override { return false; }
-        bool isJournalId(const std::string& name) const override { return false; }
-    };
-
-    class TestErrorHandler : public Compiler::ErrorHandler
-    {
-        std::vector<std::pair<std::string, Compiler::TokenLoc>> mErrors;
-
-        void report(const std::string& message, const Compiler::TokenLoc& loc, Compiler::ErrorHandler::Type type) override
-        {
-            if(type == Compiler::ErrorHandler::ErrorMessage)
-                mErrors.emplace_back(message, loc);
-        }
-
-        void report(const std::string& message, Compiler::ErrorHandler::Type type) override
-        {
-            report(message, {}, type);
-        }
-
-    public:
-        void reset() override
-        {
-            Compiler::ErrorHandler::reset();
-            mErrors.clear();
-        }
-
-        const std::vector<std::pair<std::string, Compiler::TokenLoc>>& getErrors() const { return mErrors; }
-    };
-
-    struct CompiledScript
-    {
-        std::vector<Interpreter::Type_Code> mByteCode;
-        Compiler::Locals mLocals;
-
-        CompiledScript(const std::vector<Interpreter::Type_Code>& code, const Compiler::Locals& locals) : mByteCode(code), mLocals(locals) {}
-    };
-
-    struct MWScriptTest : public ::testing::Test
-    {
-        MWScriptTest() : mErrorHandler(), mParser(mErrorHandler, mCompilerContext) {}
-
-        std::optional<CompiledScript> compile(const std::string& scriptBody)
-        {
-            mParser.reset();
-            mErrorHandler.reset();
-            std::istringstream input(scriptBody);
-            Compiler::Scanner scanner(mErrorHandler, input, mCompilerContext.getExtensions());
-            scanner.scan(mParser);
-            if(mErrorHandler.isGood())
-            {
-                std::vector<Interpreter::Type_Code> code;
-                mParser.getCode(code);
-                return CompiledScript(code, mParser.getLocals());
-            }
-            return {};
-        }
-
-        void logErrors()
-        {
-            for(const auto& [error, loc] : mErrorHandler.getErrors())
-            {
-                std::cout << error;
-                if(loc.mLine)
-                    std::cout << " at line" << loc.mLine << " column " << loc.mColumn << " (" << loc.mLiteral << ")";
-                std::cout << "\n";
-            }
-        }
-
-        void run(const CompiledScript& script)
-        {
-            // mInterpreter.run(&script.mByteCode[0], script.mByteCode.size(), interpreterContext);
-        }
-    protected:
-        void SetUp() override {}
-
-        void TearDown() override {}
-    private:
-        TestErrorHandler mErrorHandler;
-        TestCompilerContext mCompilerContext;
-        Compiler::FileParser mParser;
-        Interpreter::Interpreter mInterpreter;
-    };
-
-    const std::string sScript1 = R"mwscript(Begin basic_logic
-; Comment
-short one
-short two
-
-set one to two
-
-if ( one == two )
-    set one to 1
-elseif ( two == 1 )
-    set one to 2
-else
-    set one to 3
-endif
-
-while ( one < two )
-    set one to ( one + 1 )
-endwhile
-
-End)mwscript";
-
-    TEST_F(MWScriptTest, mwscript_test_invalid)
-    {
-        EXPECT_THROW(compile("this is not a valid script"), Compiler::SourceException);
-    }
-
-    TEST_F(MWScriptTest, mwscript_test_compilation)
-    {
-        auto script = compile(sScript1);
-        logErrors();
-        EXPECT_FALSE(!script);
-    }
+#include <gtest/gtest.h>
+
+#include <optional>
+#include <sstream>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <components/compiler/context.hpp>
+#include <components/compiler/errorhandler.hpp>
+#include <components/compiler/exception.hpp>
+#include <components/compiler/extensions.hpp>
+#include <components/compiler/extensions0.hpp>
+#include <components/compiler/fileparser.hpp>
+#include <components/compiler/opcodes.hpp>
+#include <components/compiler/scanner.hpp>
+
+#include <components/interpreter/context.hpp>
+#include <components/interpreter/installopcodes.hpp>
+#include <components/interpreter/interpreter.hpp>
+#include <components/interpreter/opcodes.hpp>
+
+namespace
+{
+    class TestCompilerContext : public Compiler::Context
+    {
+    public:
+        bool canDeclareLocals() const override { return true; }
+        char getGlobalType(const std::string& name) const override { return ' '; }
+        std::pair<char, bool> getMemberType(const std::string& name, const std::string& id) const override { return {' ', false}; }
+        bool isId(const std::string& name) const override { return false; }
+        bool isJournalId(const std::string& name) const override { return false; }
+    };
+
+    class TestErrorHandler : public Compiler::ErrorHandler
+    {
+        std::vector<std::pair<std::string, Compiler::TokenLoc>> mErrors;
+
+        void report(const std::string& message, const Compiler::TokenLoc& loc, Compiler::ErrorHandler::Type type) override
+        {
+            if(type == Compiler::ErrorHandler::ErrorMessage)
+                mErrors.emplace_back(message, loc);
+        }
+
+        void report(const std::string& message, Compiler::ErrorHandler::Type type) override
+        {
+            report(message, {}, type);
+        }
+
+    public:
+        void reset() override
+        {
+            Compiler::ErrorHandler::reset();
+            mErrors.clear();
+        }
+
+        const std::vector<std::pair<std::string, Compiler::TokenLoc>>& getErrors() const { return mErrors; }
+    };
+
+    class LocalVariables
+    {
+        std::vector<int> mShorts;
+        std::vector<int> mLongs;
+        std::vector<float> mFloats;
+
+        template<class T>
+        T getLocal(int index, const std::vector<T>& vector) const
+        {
+            if(index < vector.size())
+                return vector[index];
+            return {};
+        }
+
+        template<class T>
+        void setLocal(T value, int index, std::vector<T>& vector)
+        {
+            if(index >= vector.size())
+                vector.resize(index + 1);
+            vector[index] = value;
+        }
+    public:
+        void clear()
+        {
+            mShorts.clear();
+            mLongs.clear();
+            mFloats.clear();
+        }
+
+        int getShort(int index) const { return getLocal(index, mShorts); };
+
+        int getLong(int index) const { return getLocal(index, mLongs); };
+
+        float getFloat(int index) const { return getLocal(index, mFloats); };
+
+        void setShort(int index, int value) { setLocal(value, index, mShorts); };
+
+        void setLong(int index, int value) { setLocal(value, index, mLongs); };
+
+        void setFloat(int index, float value) { setLocal(value, index, mFloats); };
+    };
+
+    class GlobalVariables
+    {
+        std::map<std::string, int> mShorts;
+        std::map<std::string, int> mLongs;
+        std::map<std::string, float> mFloats;
+
+        template<class T>
+        T getGlobal(const std::string& name, const std::map<std::string, T>& map) const
+        {
+            auto it = map.find(name);
+            if(it != map.end())
+                return it->second;
+            return {};
+        }
+    public:
+        void clear()
+        {
+            mShorts.clear();
+            mLongs.clear();
+            mFloats.clear();
+        }
+
+        int getShort(const std::string& name) const { return getGlobal(name, mShorts); };
+
+        int getLong(const std::string& name) const { return getGlobal(name, mLongs); };
+
+        float getFloat(const std::string& name) const { return getGlobal(name, mFloats); };
+
+        void setShort(const std::string& name, int value) { mShorts[name] = value; };
+
+        void setLong(const std::string& name, int value) { mLongs[name] = value; };
+
+        void setFloat(const std::string& name, float value) { mFloats[name] = value; };
+    };
+
+    class TestInterpreterContext : public Interpreter::Context
+    {
+        LocalVariables mLocals;
+        std::map<std::string, GlobalVariables> mMembers;
+    public:
+        std::string getTarget() const override { return {}; };
+
+        int getLocalShort(int index) const override { return mLocals.getShort(index); };
+
+        int getLocalLong(int index) const override { return mLocals.getLong(index); };
+
+        float getLocalFloat(int index) const override { return mLocals.getFloat(index); };
+
+        void setLocalShort(int index, int value) override { mLocals.setShort(index, value); };
+
+        void setLocalLong(int index, int value) override { mLocals.setLong(index, value); };
+
+        void setLocalFloat(int index, float value) override { mLocals.setFloat(index, value); };
+
+        void messageBox(const std::string& message, const std::vector<std::string>& buttons) override {};
+
+        void report(const std::string& message) override { std::cout << message << "\n"; };
+
+        int getGlobalShort(const std::string& name) const override { return {}; };
+
+        int getGlobalLong(const std::string& name) const override { return {}; };
+
+        float getGlobalFloat(const std::string& name) const override { return {}; };
+
+        void setGlobalShort(const std::string& name, int value) override {};
+
+        void setGlobalLong(const std::string& name, int value) override {};
+
+        void setGlobalFloat(const std::string& name, float value) override {};
+
+        std::vector<std::string> getGlobals() const override { return {}; };
+
+        char getGlobalType(const std::string& name) const override { return ' '; };
+
+        std::string getActionBinding(const std::string& action) const override { return {}; };
+
+        std::string getActorName() const override { return {}; };
+
+        std::string getNPCRace() const override { return {}; };
+
+        std::string getNPCClass() const override { return {}; };
+
+        std::string getNPCFaction() const override { return {}; };
+
+        std::string getNPCRank() const override { return {}; };
+
+        std::string getPCName() const override { return {}; };
+
+        std::string getPCRace() const override { return {}; };
+
+        std::string getPCClass() const override { return {}; };
+
+        std::string getPCRank() const override { return {}; };
+
+        std::string getPCNextRank() const override { return {}; };
+
+        int getPCBounty() const override { return {}; };
+
+        std::string getCurrentCellName() const override { return {}; };
+
+        int getMemberShort(const std::string& id, const std::string& name, bool global) const override
+        {
+            auto it = mMembers.find(id);
+            if(it != mMembers.end())
+                return it->second.getShort(name);
+            return {};
+        };
+
+        int getMemberLong(const std::string& id, const std::string& name, bool global) const override
+        {
+            auto it = mMembers.find(id);
+            if(it != mMembers.end())
+                return it->second.getLong(name);
+            return {};
+        };
+
+        float getMemberFloat(const std::string& id, const std::string& name, bool global) const override
+        {
+            auto it = mMembers.find(id);
+            if(it != mMembers.end())
+                return it->second.getFloat(name);
+            return {};
+        };
+
+        void setMemberShort(const std::string& id, const std::string& name, int value, bool global) override { mMembers[id].setShort(name, value); };
+
+        void setMemberLong(const std::string& id, const std::string& name, int value, bool global) override { mMembers[id].setLong(name, value); };
+
+        void setMemberFloat(const std::string& id, const std::string& name, float value, bool global) override { mMembers[id].setFloat(name, value); };
+    };
+
+    struct CompiledScript
+    {
+        std::vector<Interpreter::Type_Code> mByteCode;
+        Compiler::Locals mLocals;
+
+        CompiledScript(const std::vector<Interpreter::Type_Code>& code, const Compiler::Locals& locals) : mByteCode(code), mLocals(locals) {}
+    };
+
+    struct MWScriptTest : public ::testing::Test
+    {
+        MWScriptTest() : mErrorHandler(), mParser(mErrorHandler, mCompilerContext) {}
+
+        std::optional<CompiledScript> compile(const std::string& scriptBody, bool shouldFail = false)
+        {
+            mParser.reset();
+            mErrorHandler.reset();
+            std::istringstream input(scriptBody);
+            Compiler::Scanner scanner(mErrorHandler, input, mCompilerContext.getExtensions());
+            scanner.scan(mParser);
+            if(mErrorHandler.isGood())
+            {
+                std::vector<Interpreter::Type_Code> code;
+                mParser.getCode(code);
+                return CompiledScript(code, mParser.getLocals());
+            }
+            else if(!shouldFail)
+                logErrors();
+            return {};
+        }
+
+        void logErrors()
+        {
+            for(const auto& [error, loc] : mErrorHandler.getErrors())
+            {
+                std::cout << error;
+                if(loc.mLine)
+                    std::cout << " at line" << loc.mLine << " column " << loc.mColumn << " (" << loc.mLiteral << ")";
+                std::cout << "\n";
+            }
+        }
+
+        void registerExtensions()
+        {
+            Compiler::registerExtensions(mExtensions);
+            mCompilerContext.setExtensions(&mExtensions);
+        }
+
+        void run(const CompiledScript& script, TestInterpreterContext& context)
+        {
+            mInterpreter.run(&script.mByteCode[0], script.mByteCode.size(), context);
+        }
+
+        void installOpcode(int code, Interpreter::Opcode0* opcode)
+        {
+            mInterpreter.installSegment5(code, opcode);
+        }
+    protected:
+        void SetUp() override
+        {
+            Interpreter::installOpcodes(mInterpreter);
+        }
+
+        void TearDown() override {}
+    private:
+        TestErrorHandler mErrorHandler;
+        TestCompilerContext mCompilerContext;
+        Compiler::FileParser mParser;
+        Compiler::Extensions mExtensions;
+        Interpreter::Interpreter mInterpreter;
+    };
+
+    const std::string sScript1 = R"mwscript(Begin basic_logic
+; Comment
+short one
+short two
+
+set one to two
+
+if ( one == two )
+    set one to 1
+elseif ( two == 1 )
+    set one to 2
+else
+    set one to 3
+endif
+
+while ( one < two )
+    set one to ( one + 1 )
+endwhile
+
+End)mwscript";
+
+    const std::string sScript2 = R"mwscript(Begin addtopic
+
+AddTopic "OpenMW Unit Test"
+
+End)mwscript";
+
+    TEST_F(MWScriptTest, mwscript_test_invalid)
+    {
+        EXPECT_THROW(compile("this is not a valid script", true), Compiler::SourceException);
+    }
+
+    TEST_F(MWScriptTest, mwscript_test_compilation)
+    {
+        EXPECT_FALSE(!compile(sScript1));
+    }
+
+    TEST_F(MWScriptTest, mwscript_test_no_extensions)
+    {
+        EXPECT_THROW(compile(sScript2, true), Compiler::SourceException);
+    }
+
+    TEST_F(MWScriptTest, mwscript_test_function)
+    {
+        registerExtensions();
+        if(auto script = compile(sScript2))
+        {
+            class AddTopic : public Interpreter::Opcode0
+            {
+            public:
+                void execute(Interpreter::Runtime& runtime)
+                {
+                    const auto topic = runtime.getStringLiteral(runtime[0].mInteger);
+                    runtime.pop();
+                    EXPECT_EQ(topic, "OpenMW Unit Test");
+                }
+            };
+            installOpcode(Compiler::Dialogue::opcodeAddTopic, new AddTopic);
+            TestInterpreterContext context;
+            run(*script, context);
+        }
+        else
+        {
+            FAIL();
+        }
+    }
 }
\ No newline at end of file