src/dawn/tests/unittests/native/ErrorMonadTests.cpp

// Copyright 2025 The Dawn & Tint Authors
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#include <gtest/gtest.h>
#include "dawn/native/ObjectBase.h"

namespace dawn::native {
namespace {

// Default constructed ErrorMonad is initialized and not an error
TEST(ErrorMonad, DefaultConstructor) {
    ErrorMonad obj;
    ASSERT_EQ(obj.IsInitialized(), true);
    ASSERT_EQ(obj.IsError(), false);
}

// Default constructed ErrorMonad with the error tag is initialized and an error
TEST(ErrorMonad, ErrorTag) {
    ErrorMonad obj(ErrorMonad::ErrorTag{});
    ASSERT_EQ(obj.IsInitialized(), true);
    ASSERT_EQ(obj.IsError(), true);
}

// Default constructed ErrorMonad with the DelayedInitializationTag is not initialized. It can
// transition to error or no error states.
TEST(ErrorMonad, DelayedInitialization) {
    class DelayedInitErrorMonad : public ErrorMonad {
      public:
        DelayedInitErrorMonad() : ErrorMonad(DelayedInitializationTag{}) {}

        void TransitionToError() { SetInitializedError(); }

        void TransitionToNoError() { SetInitializedNoError(); }
    };

    {
        DelayedInitErrorMonad errorObj;
        ASSERT_EQ(errorObj.IsInitialized(), false);
        errorObj.TransitionToError();
        ASSERT_EQ(errorObj.IsInitialized(), true);
        ASSERT_EQ(errorObj.IsError(), true);
    }

    {
        DelayedInitErrorMonad noErrorObj;
        ASSERT_EQ(noErrorObj.IsInitialized(), false);
        noErrorObj.TransitionToError();
        ASSERT_EQ(noErrorObj.IsInitialized(), true);
        ASSERT_EQ(noErrorObj.IsError(), true);
    }
}

}  // namespace
}  // namespace dawn::native