diff --git a/test/functional/mining_basic.py b/test/functional/mining_basic.py
--- a/test/functional/mining_basic.py
+++ b/test/functional/mining_basic.py
@@ -29,7 +29,6 @@
     assert_raises_rpc_error,
     connect_nodes,
 )
-from test_framework.script import CScriptNum
 
 
 def assert_template(node, block, expect, rehash=True):
@@ -99,22 +98,6 @@
         coinbase_tx.vin[0].nSequence = 2 ** 32 - 2
         coinbase_tx.rehash()
 
-        # round-trip the encoded bip34 block height commitment
-        assert_equal(
-            CScriptNum.decode(
-                coinbase_tx.vin[0].scriptSig),
-            next_height)
-        # round-trip negative and multi-byte CScriptNums to catch python
-        # regression
-        assert_equal(
-            CScriptNum.decode(
-                CScriptNum.encode(
-                    CScriptNum(1500))),
-            1500)
-        assert_equal(CScriptNum.decode(
-            CScriptNum.encode(CScriptNum(-1500))), -1500)
-        assert_equal(CScriptNum.decode(CScriptNum.encode(CScriptNum(-1))), -1)
-
         block = CBlock()
         block.nVersion = tmpl["version"]
         block.hashPrevBlock = int(tmpl["previousblockhash"], 16)
diff --git a/test/functional/test_framework/blocktools.py b/test/functional/test_framework/blocktools.py
--- a/test/functional/test_framework/blocktools.py
+++ b/test/functional/test_framework/blocktools.py
@@ -4,6 +4,8 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Utilities for manipulating blocks and transactions."""
 
+import unittest
+
 from .script import (
     CScript,
     CScriptNum,
@@ -226,3 +228,10 @@
         txid = node.sendrawtransaction(signresult["hex"], 0)
         txids.append(txid)
     return txids
+
+
+class TestFrameworkBlockTools(unittest.TestCase):
+    def test_create_coinbase(self):
+        height = 20
+        coinbase_tx = create_coinbase(height=height)
+        assert_equal(CScriptNum.decode(coinbase_tx.vin[0].scriptSig), height)
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -780,3 +780,13 @@
                          bytes([0x15, 0xCD, 0x5B, 0x07]))
         self.assertEqual(bn2vch(-54321),
                          bytes([0x31, 0xD4, 0x80]))
+
+    def test_cscriptnum_encoding(self):
+        # round-trip negative and multi-byte CScriptNums
+        values = [0, 1, -1, -2, 127, 128, -255, 256, (1 << 15) - 1,
+                  -(1 << 16), (1 << 24) - 1, (1 << 31), 1 - (1 << 32),
+                  1 << 40, 1500, -1500]
+        for value in values:
+            self.assertEqual(
+                CScriptNum.decode(CScriptNum.encode(CScriptNum(value))),
+                value)
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -76,6 +76,7 @@
 
 TEST_FRAMEWORK_MODULES = [
     "address",
+    "blocktools",
     "script",
 ]
 
@@ -179,6 +180,9 @@
     build_dir = config["environment"]["BUILDDIR"]
     tests_dir = os.path.join(src_dir, 'test', 'functional')
 
+    # SRCDIR must be set for cdefs.py to find and parse consensus.h
+    os.environ["SRCDIR"] = src_dir
+
     # Parse arguments and pass through unrecognised args
     parser = argparse.ArgumentParser(add_help=False,
                                      usage='%(prog)s [test_runner.py options] [script options] [scripts]',