diff --git a/src/test/blockindex_tests.cpp b/src/test/blockindex_tests.cpp
--- a/src/test/blockindex_tests.cpp
+++ b/src/test/blockindex_tests.cpp
@@ -141,4 +141,20 @@
     }
 }
 
+BOOST_AUTO_TEST_CASE(index_isvalid) {
+    CBlockIndex index;
+    for (int validity = 0; validity <= 5; validity++) {
+        index.nStatus = BlockStatus().withValidity(BlockValidity(validity));
+
+        for (int validUpTo = 0; validUpTo <= 5; validUpTo++) {
+            bool isValid = index.IsValid(BlockValidity(validUpTo));
+            if (validUpTo <= validity) {
+                BOOST_CHECK(isValid);
+            } else {
+                BOOST_CHECK(!isValid);
+            }
+        }
+    }
+}
+
 BOOST_AUTO_TEST_SUITE_END()