Always-active versionbits support

src/consensus/params.h

@@ -35,6 +35,12 @@ struct BIP9Deployment {
 
     /** Constant for nTimeout very far in the future. */
     static constexpr int64_t NO_TIMEOUT = std::numeric_limits<int64_t>::max();
+
+    /** Special value for nStartTime indicating that the deployment is always active.
+     *  This is useful for testing, as it means tests don't need to deal with the activation
+     *  process (which takes at least 3 BIP9 intervals). Only tests that specifically test the
+     *  behaviour during activation cannot use this. */
+    static constexpr int64_t ALWAYS_ACTIVE = -1;
 };
 
 /**