Add facility and test for checking if Axion upgrade is enabled

Summary: This can be used for activating changes going into the next upgrade.

Test Plan: `ninja check`

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D6780

src/consensus/activation.cpp

@@ -71,3 +71,13 @@ bool IsPhononEnabled(const Consensus::Params &params,
     return pindexPrev->GetMedianTimePast() >=
            gArgs.GetArg("-phononactivationtime", params.phononActivationTime);
 }
+
+bool IsAxionEnabled(const Consensus::Params &params,
+                    const CBlockIndex *pindexPrev) {
+    if (pindexPrev == nullptr) {
+        return false;
+    }
+
+    return pindexPrev->GetMedianTimePast() >=
+           gArgs.GetArg("-axionactivationtime", params.axionActivationTime);
+}

src/consensus/activation.h

@@ -35,4 +35,8 @@ bool IsGravitonEnabled(const Consensus::Params &params,
 bool IsPhononEnabled(const Consensus::Params &params,
                      const CBlockIndex *pindexPrev);
 
+/** Check if November 15th, 2020 protocol upgrade has activated. */
+bool IsAxionEnabled(const Consensus::Params &params,
+                    const CBlockIndex *pindexPrev);
+
 #endif // BITCOIN_CONSENSUS_ACTIVATION_H

src/init.cpp

@@ -367,7 +367,11 @@ void SetupServerArgs() {
         // GUI args. These will be overwritten by SetupUIArgs for the GUI
         "-allowselfsignedrootcertificates", "-choosedatadir", "-lang=<lang>",
         "-min", "-resetguisettings", "-rootcertificates=<file>", "-splash",
-        "-uiplatform"};
+        "-uiplatform",
+        // TODO remove after the May 2020 upgrade
+        "-phononactivationtime",
+        // TODO remove after the November 2020 upgrade
+        "-axionactivationtime"};
 
     // Set all of the args and their help
     // When adding new options to the categories, please keep and ensure alphabetical ordering.

src/test/activation_tests.cpp

@@ -67,4 +67,30 @@ BOOST_AUTO_TEST_CASE(isphononenabled) {
     BOOST_CHECK(IsPhononEnabled(params, &blocks.back()));
 }
 
+BOOST_AUTO_TEST_CASE(isaxionenabled) {
+    CBlockIndex prev;
+
+    const Consensus::Params &params = Params().GetConsensus();
+    const auto activation =
+        gArgs.GetArg("-axionactivationtime", params.axionActivationTime);
+    SetMockTime(activation - 1000000);
+
+    BOOST_CHECK(!IsAxionEnabled(params, nullptr));
+
+    std::array<CBlockIndex, 12> blocks;
+    for (size_t i = 1; i < blocks.size(); ++i) {
+        blocks[i].pprev = &blocks[i - 1];
+    }
+    BOOST_CHECK(!IsAxionEnabled(params, &blocks.back()));
+
+    SetMTP(blocks, activation - 1);
+    BOOST_CHECK(!IsAxionEnabled(params, &blocks.back()));
+
+    SetMTP(blocks, activation);
+    BOOST_CHECK(IsAxionEnabled(params, &blocks.back()));
+
+    SetMTP(blocks, activation + 1);
+    BOOST_CHECK(IsAxionEnabled(params, &blocks.back()));
+}
+
 BOOST_AUTO_TEST_SUITE_END()