[tests] don't override __init__() in individual tests

Almost all test scripts currently need to override the __init__()
method. When they do that they need to call into super().__init__() as
the base class does some generic initialization.

This commit makes the base class __init__() call into set_test_params()
method. Individual test cases can override set_test_params() to setup
their test parameters.

1 files changed, 2 insertions, 3 deletions

diff --git a/test/functional/bip9-softforks.py b/test/functional/bip9-softforks.py
index ad16482550..904789301a 100755
--- a/test/functional/bip9-softforks.py
+++ b/test/functional/bip9-softforks.py
@@ -28,11 +28,10 @@ from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript, OP_1NEGATE, OP_CHECKSEQUENCEVERIFY, OP_DROP
 
 class BIP9SoftForksTest(ComparisonTestFramework):
-
-    def __init__(self):
-        super().__init__()
+    def set_test_params(self):
         self.num_nodes = 1
         self.extra_args = [['-whitelist=127.0.0.1']]
+        self.setup_clean_chain = True
 
     def run_test(self):
         self.test = TestManager(self, self.options.tmpdir)