src/base/memoizer.test.cc

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#include <gtest/gtest.h>

#include "base/memoizer.hh"

using namespace gem5;

namespace
{

uint32_t
fibonacci(uint32_t n)
{
    if (n == 0) return 0;
    if (n == 1) return 1;

    return fibonacci(n-1) + fibonacci(n-2);
}

using FibonacciMemoizer = decltype(Memoizer(fibonacci));

class FibonacciMemoizerFixture : public FibonacciMemoizer,
                                 public ::testing::Test
{
  public:
    FibonacciMemoizerFixture()
      : FibonacciMemoizer(fibonacci)
    {}

};

}

/**
 * Testing result cache before and after a memoized call
 */
TEST_F(FibonacciMemoizerFixture, Uncached)
{
    const auto res10 = fibonacci(10);

    // Fresh memoizer, input = 10 shouldn't be present
    ASSERT_FALSE(cached(10));

    // We are now memoizing the result and making sure
    // it provides the same value
    EXPECT_EQ((*this)(10), res10);

    // Now the fibonacci output for input = 10 should be cached
    ASSERT_TRUE(cached(10));
}

/**
 * Just checking memoization works for multiple values
 */
TEST_F(FibonacciMemoizerFixture, MultipleValues)
{
    const auto res0 = fibonacci(0);
    const auto res10 = fibonacci(10);
    const auto res20 = fibonacci(20);

    EXPECT_EQ((*this)(0), res0);
    EXPECT_EQ((*this)(10), res10);
    EXPECT_EQ((*this)(20), res20);

    EXPECT_EQ(cacheSize(), 3);

    EXPECT_TRUE(cached(0));
    EXPECT_TRUE(cached(10));
    EXPECT_TRUE(cached(20));

    // fibonacci(30) shouldn't be cached
    EXPECT_FALSE(cached(30));
}

/**
 * Testing the Memoizer::flush method
 */
TEST_F(FibonacciMemoizerFixture, CacheFlush)
{
    const auto res10 = fibonacci(10);

    ASSERT_EQ(cacheSize(), 0);

    // Memoizing fibonacci(10)
    EXPECT_EQ((*this)(10), res10);
    ASSERT_EQ(cacheSize(), 1);

    // Flushing the cache
    flush();

    // Cache should be empty now
    ASSERT_EQ(cacheSize(), 0);
}