Auto merge of #2386 - str4d:2385-consensus-correction, r=str4d

Correct consensus logic in ContextualCheckInputs

Closes #2385.

src/Makefile.gtest.include

@@ -32,6 +32,7 @@ zcash_gtest_SOURCES += \
 	gtest/test_random.cpp \
 	gtest/test_rpc.cpp \
 	gtest/test_transaction.cpp \
+	gtest/test_validation.cpp \
 	gtest/test_circuit.cpp \
 	gtest/test_txid.cpp \
 	gtest/test_libzcash_utils.cpp \

src/gtest/test_validation.cpp

@@ -0,0 +1,63 @@
+#include <gtest/gtest.h>
+
+#include "consensus/validation.h"
+#include "main.h"
+
+// Fake an empty view
+class FakeCoinsViewDB : public CCoinsView {
+public:
+    FakeCoinsViewDB() {}
+
+    bool GetAnchorAt(const uint256 &rt, ZCIncrementalMerkleTree &tree) const {
+        return false;
+    }
+
+    bool GetNullifier(const uint256 &nf) const {
+        return false;
+    }
+
+    bool GetCoins(const uint256 &txid, CCoins &coins) const {
+        return false;
+    }
+
+    bool HaveCoins(const uint256 &txid) const {
+        return false;
+    }
+
+    uint256 GetBestBlock() const {
+        uint256 a;
+        return a;
+    }
+
+    uint256 GetBestAnchor() const {
+        uint256 a;
+        return a;
+    }
+
+    bool BatchWrite(CCoinsMap &mapCoins,
+                    const uint256 &hashBlock,
+                    const uint256 &hashAnchor,
+                    CAnchorsMap &mapAnchors,
+                    CNullifiersMap &mapNullifiers) {
+        return false;
+    }
+
+    bool GetStats(CCoinsStats &stats) const {
+        return false;
+    }
+};
+
+TEST(Validation, ContextualCheckInputsPassesWithCoinbase) {
+    // Create fake coinbase transaction
+    CMutableTransaction mtx;
+    mtx.vin.resize(1);
+    CTransaction tx(mtx);
+    ASSERT_TRUE(tx.IsCoinBase());
+
+    // Fake an empty view
+    FakeCoinsViewDB fakeDB;
+    CCoinsViewCache view(&fakeDB);
+
+    CValidationState state;
+    EXPECT_TRUE(ContextualCheckInputs(tx, state, view, false, 0, false, Params(CBaseChainParams::MAIN).GetConsensus()));
+}

src/main.cpp

@@ -1687,11 +1687,12 @@ bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoins
 
 bool ContextualCheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams, std::vector<CScriptCheck> *pvChecks)
 {
-    if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs), consensusParams))
-        return false;
-
     if (!tx.IsCoinBase())
     {
+        if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs), consensusParams)) {
+            return false;
+        }
+
         if (pvChecks)
             pvChecks->reserve(tx.vin.size());