From 4b32181dbbe32f9cd9f8c2063bd31b27746f794d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C5=91rinc?= <pap.lorinc@gmail.com>
Date: Wed, 14 Jan 2026 23:43:24 +0100
Subject: [PATCH] test: add `HaveInputs` call-path unit tests

Add unit tests covering `CCoinsViewCache::HaveInputs()`.

The tests document that `HaveInputs()` consults the cache first and that a cache miss pulls from the backing view via `GetCoin()`.
---
 src/test/coins_tests.cpp | 87 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/src/test/coins_tests.cpp b/src/test/coins_tests.cpp
index 8c0756d8528..ad182559a33 100644
--- a/src/test/coins_tests.cpp
+++ b/src/test/coins_tests.cpp
@@ -1050,6 +1050,93 @@ BOOST_FIXTURE_TEST_CASE(ccoins_flush_behavior, FlushTest)
     }
 }
 
+BOOST_AUTO_TEST_CASE(ccoins_haveinputs_cache_miss_uses_base_getcoin)
+{
+    const COutPoint prevout{Txid::FromUint256(m_rng.rand256()), 0};
+
+    CCoinsViewDB db{{.path = "test", .cache_bytes = 1_MiB, .memory_only = true}, {}};
+    {
+        CCoinsViewCache write_cache{&db};
+        write_cache.SetBestBlock(m_rng.rand256());
+        write_cache.AddCoin(prevout, Coin{CTxOut{1, CScript{}}, 1, false}, /*possible_overwrite=*/false);
+        write_cache.Flush();
+    }
+
+    class CCoinsViewSpy final : public CCoinsViewBacked
+    {
+    public:
+        const COutPoint expected;
+        mutable size_t havecoin_calls{0}, getcoin_calls{0};
+
+        explicit CCoinsViewSpy(CCoinsView* view, const COutPoint& out) : CCoinsViewBacked(view), expected{out} {}
+
+        std::optional<Coin> GetCoin(const COutPoint& out) const override
+        {
+            ++getcoin_calls;
+            BOOST_CHECK(out == expected);
+            return CCoinsViewBacked::GetCoin(out);
+        }
+
+        bool HaveCoin(const COutPoint& out) const override
+        {
+            ++havecoin_calls;
+            BOOST_CHECK(out == expected);
+            return CCoinsViewBacked::HaveCoin(out);
+        }
+    };
+
+    CCoinsViewSpy base{&db, prevout};
+    CCoinsViewCache cache{&base};
+
+    CMutableTransaction mtx;
+    mtx.vin.emplace_back(prevout);
+    const CTransaction tx{mtx};
+    BOOST_CHECK(!tx.IsCoinBase());
+
+    BOOST_CHECK(cache.HaveInputs(tx));
+    BOOST_CHECK_EQUAL(base.getcoin_calls, 1);
+    BOOST_CHECK_EQUAL(base.havecoin_calls, 0);
+}
+
+BOOST_AUTO_TEST_CASE(ccoins_cache_hit_does_not_call_base)
+{
+    class CCoinsViewNoCall final : public CCoinsView
+    {
+    public:
+        std::optional<Coin> GetCoin(const COutPoint&) const override
+        {
+            BOOST_FAIL("Base GetCoin should not be called when input is cached");
+            return std::nullopt;
+        }
+
+        bool HaveCoin(const COutPoint&) const override
+        {
+            BOOST_FAIL("Base HaveCoin should not be called when input is cached");
+            return false;
+        }
+    };
+
+    const COutPoint prevout{Txid::FromUint256(m_rng.rand256()), 0};
+    CCoinsViewNoCall base;
+    CCoinsViewCache cache{&base};
+
+    cache.AddCoin(prevout, Coin{CTxOut{1, CScript{}}, 1, false}, /*possible_overwrite=*/false);
+    BOOST_CHECK(cache.HaveCoinInCache(prevout));
+
+    BOOST_CHECK(!cache.AccessCoin(prevout).IsSpent());
+    BOOST_CHECK(cache.GetCoin(prevout));
+    BOOST_CHECK(cache.HaveCoin(prevout));
+
+    CMutableTransaction mtx;
+    mtx.vin.emplace_back(prevout);
+    const CTransaction tx{mtx};
+    BOOST_CHECK(!tx.IsCoinBase());
+    BOOST_CHECK(cache.HaveInputs(tx));
+
+    BOOST_CHECK(cache.SpendCoin(prevout));
+    BOOST_CHECK(!cache.HaveCoinInCache(prevout));
+}
+
 BOOST_AUTO_TEST_CASE(coins_resource_is_used)
 {
     CCoinsMapMemoryResource resource;