Method TestFlushBehavior

src/test/coins_tests.cpp:900–1047

For CCoinsViewCache instances backed by either another cache instance or leveldb, test cache behavior and flag state (DIRTY/FRESH) by 1. Adding a random coin to the child-most cache, 2. Flushing all caches (without erasing), 3. Ensure the entry still exists in the cache and has been written to parent, 4. (if `do_erasing_flush`) Flushing the caches again (with erasing), 5. (if `do_erasing_flush`)

//! 6. Spend the coin, ensure it no longer exists in the parent.
//!
void TestFlushBehavior(
    CCoinsViewCacheTest* view,
    CCoinsViewDB& base,
    std::vector<std::unique_ptr<CCoinsViewCacheTest>>& all_caches,
    bool do_erasing_flush)
{
    size_t cache_usage;
    size_t cache_size;

    auto flush_all = [this, &all_caches](bool erase) {
        // Flush in reverse order to ensure that flushes happen from children up.
        for (auto i = all_caches.rbegin(); i != all_caches.rend(); ++i) {
            auto& cache = *i;
            cache->SanityCheck();
            // block_hash must be filled before flushing to disk; value is
            // unimportant here. This is normally done during connect/disconnect block.
            cache->SetBestBlock(m_rng.rand256());
            erase ? cache->Flush() : cache->Sync();
        }
    };

    Txid txid = Txid::FromUint256(m_rng.rand256());
    COutPoint outp = COutPoint(txid, 0);
    Coin coin = MakeCoin();
    // Ensure the coins views haven't seen this coin before.
    BOOST_CHECK(!base.HaveCoin(outp));
    BOOST_CHECK(!view->HaveCoin(outp));

    // --- 1. Adding a random coin to the child cache
    //
    view->AddCoin(outp, Coin(coin), false);

    cache_usage = view->DynamicMemoryUsage();
    cache_size = view->map().size();

    // `base` shouldn't have coin (no flush yet) but `view` should have cached it.
    BOOST_CHECK(!base.HaveCoin(outp));
    BOOST_CHECK(view->HaveCoin(outp));

    BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), CoinEntry(coin.out.nValue, CoinEntry::State::DIRTY_FRESH));

    // --- 2. Flushing all caches (without erasing)
    //
    flush_all(/*erase=*/ false);

    // CoinsMap usage should be unchanged since we didn't erase anything.
    BOOST_CHECK_EQUAL(cache_usage, view->DynamicMemoryUsage());
    BOOST_CHECK_EQUAL(cache_size, view->map().size());

    // --- 3. Ensuring the entry still exists in the cache and has been written to parent
    //
    BOOST_CHECK_EQUAL(GetCoinsMapEntry(view->map(), outp), CoinEntry(coin.out.nValue, CoinEntry::State::CLEAN)); // State should have been wiped.

    // Both views should now have the coin.
    BOOST_CHECK(base.HaveCoin(outp));
    BOOST_CHECK(view->HaveCoin(outp));

    if (do_erasing_flush) {