Merge #14903: tests: Handle ImportError explicitly, improve comparisons against None

c9ba253f4f5d675d7736d24c1167229d0898ef1a Add E711 to flake8 check (Daniel Ingram)
17b55202dae8d6e21d2490de89b345c55f7694c0 Compare to None with is/is not (Daniel Ingram)
1b89074ae27ce123adbeed57343deaef13c14f81 Change '== None' to 'is None' (Daniel Ingram)
16d293772365d57cc1a279d5ad0fa6f44b12ed54 Handle exception as ImportError (Daniel Ingram)

Pull request description:

Tree-SHA512: aa5875ea3d9ac47ac898545ff023b511042cd377ea0c4594074daae119f3d4f3fc295721aad94a732a907086ecb32bce19a8eed38adf479f12663c4e8944f721

9 files changed, 18 insertions, 17 deletions

diff --git a/contrib/devtools/clang-format-diff.py b/contrib/devtools/clang-format-diff.py
index 77e845a9b4..f322b3a880 100755
--- a/contrib/devtools/clang-format-diff.py
+++ b/contrib/devtools/clang-format-diff.py
@@ -109,7 +109,7 @@ def main():
     match = re.search('^\+\+\+\ (.*?/){%s}(\S*)' % args.p, line)
     if match:
       filename = match.group(2)
-    if filename == None:
+    if filename is None:
       continue
 
     if args.regex is not None:
diff --git a/contrib/devtools/copyright_header.py b/contrib/devtools/copyright_header.py
index 2d539ffe43..6d7a592f01 100755
--- a/contrib/devtools/copyright_header.py
+++ b/contrib/devtools/copyright_header.py
@@ -491,7 +491,7 @@ def get_git_change_year_range(filename):
 
 def file_already_has_core_copyright(file_lines):
     index, _ = get_updatable_copyright_line(file_lines)
-    return index != None
+    return index is not None
 
 ################################################################################
 # insert header execution
diff --git a/contrib/devtools/github-merge.py b/contrib/devtools/github-merge.py
index 4e90f85f50..c7a64bd6f9 100755
--- a/contrib/devtools/github-merge.py
+++ b/contrib/devtools/github-merge.py
@@ -25,7 +25,7 @@ import json
 import codecs
 try:
     from urllib.request import Request,urlopen
-except:
+except ImportError:
     from urllib2 import Request,urlopen
 
 # External tools (can be overridden using environment)
diff --git a/contrib/devtools/update-translations.py b/contrib/devtools/update-translations.py
index f0098cfcdf..1b9d3a4c27 100755
--- a/contrib/devtools/update-translations.py
+++ b/contrib/devtools/update-translations.py
@@ -125,7 +125,7 @@ def escape_cdata(text):
     return text
 
 def contains_bitcoin_addr(text, errors):
-    if text != None and ADDRESS_REGEXP.search(text) != None:
+    if text is not None and ADDRESS_REGEXP.search(text) is not None:
         errors.append('Translation "%s" contains a bitcoin address. This will be removed.' % (text))
         return True
     return False
diff --git a/test/functional/interface_http.py b/test/functional/interface_http.py
index e4b86f9e1e..20889366e5 100755
--- a/test/functional/interface_http.py
+++ b/test/functional/interface_http.py
@@ -31,13 +31,13 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1)
-        assert(conn.sock!=None) #according to http/1.1 connection must still be open!
+        assert(conn.sock is not None) #according to http/1.1 connection must still be open!
 
         #send 2nd request without closing connection
         conn.request('POST', '/', '{"method": "getchaintips"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1) #must also response with a correct json-rpc message
-        assert(conn.sock!=None) #according to http/1.1 connection must still be open!
+        assert(conn.sock is not None) #according to http/1.1 connection must still be open!
         conn.close()
 
         #same should be if we add keep-alive because this should be the std. behaviour
@@ -48,13 +48,13 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1)
-        assert(conn.sock!=None) #according to http/1.1 connection must still be open!
+        assert(conn.sock is not None) #according to http/1.1 connection must still be open!
 
         #send 2nd request without closing connection
         conn.request('POST', '/', '{"method": "getchaintips"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1) #must also response with a correct json-rpc message
-        assert(conn.sock!=None) #according to http/1.1 connection must still be open!
+        assert(conn.sock is not None) #according to http/1.1 connection must still be open!
         conn.close()
 
         #now do the same with "Connection: close"
@@ -65,7 +65,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1)
-        assert(conn.sock==None) #now the connection must be closed after the response
+        assert(conn.sock is None) #now the connection must be closed after the response
 
         #node1 (2nd node) is running with disabled keep-alive option
         urlNode1 = urllib.parse.urlparse(self.nodes[1].url)
@@ -88,7 +88,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.request('POST', '/', '{"method": "getbestblockhash"}', headers)
         out1 = conn.getresponse().read()
         assert(b'"error":null' in out1)
-        assert(conn.sock!=None) #connection must be closed because bitcoind should use keep-alive by default
+        assert(conn.sock is not None) #connection must be closed because bitcoind should use keep-alive by default
 
         # Check excessive request size
         conn = http.client.HTTPConnection(urlNode2.hostname, urlNode2.port)
diff --git a/test/functional/mining_prioritisetransaction.py b/test/functional/mining_prioritisetransaction.py
index c5ddee56f1..da16bfbbfb 100755
--- a/test/functional/mining_prioritisetransaction.py
+++ b/test/functional/mining_prioritisetransaction.py
@@ -84,7 +84,7 @@ class PrioritiseTransactionTest(BitcoinTestFramework):
                 high_fee_tx = x
 
         # Something high-fee should have been mined!
-        assert(high_fee_tx != None)
+        assert(high_fee_tx is not None)
 
         # Add a prioritisation before a tx is in the mempool (de-prioritising a
         # high-fee transaction so that it's now low fee).
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index c72cb8835c..c2829bd328 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -764,7 +764,7 @@ class HeaderAndShortIDs:
         self.prefilled_txn = []
         self.use_witness = False
 
-        if p2pheaders_and_shortids != None:
+        if p2pheaders_and_shortids is not None:
             self.header = p2pheaders_and_shortids.header
             self.nonce = p2pheaders_and_shortids.nonce
             self.shortids = p2pheaders_and_shortids.shortids
@@ -822,7 +822,7 @@ class BlockTransactionsRequest:
 
     def __init__(self, blockhash=0, indexes = None):
         self.blockhash = blockhash
-        self.indexes = indexes if indexes != None else []
+        self.indexes = indexes if indexes is not None else []
 
     def deserialize(self, f):
         self.blockhash = deser_uint256(f)
@@ -863,7 +863,7 @@ class BlockTransactions:
 
     def __init__(self, blockhash=0, transactions = None):
         self.blockhash = blockhash
-        self.transactions = transactions if transactions != None else []
+        self.transactions = transactions if transactions is not None else []
 
     def deserialize(self, f):
         self.blockhash = deser_uint256(f)
@@ -1052,7 +1052,7 @@ class msg_getdata:
     command = b"getdata"
 
     def __init__(self, inv=None):
-        self.inv = inv if inv != None else []
+        self.inv = inv if inv is not None else []
 
     def deserialize(self, f):
         self.inv = deser_vector(f, CInv)
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index ebae3faffc..031a8824b1 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -68,7 +68,7 @@ class TestNode():
         self.rpc_timeout = timewait
         self.binary = bitcoind
         self.coverage_dir = coverage_dir
-        if extra_conf != None:
+        if extra_conf is not None:
             append_config(datadir, extra_conf)
         # Most callers will just need to add extra args to the standard list below.
         # For those callers that need more flexibility, they can just set the args property directly.
diff --git a/test/lint/lint-python.sh b/test/lint/lint-python.sh
index d44a585294..3dbb9fff28 100755
--- a/test/lint/lint-python.sh
+++ b/test/lint/lint-python.sh
@@ -36,6 +36,7 @@ export LC_ALL=C
 # E701 multiple statements on one line (colon)
 # E702 multiple statements on one line (semicolon)
 # E703 statement ends with a semicolon
+# E711 comparison to None should be 'if cond is None:'
 # E714 test for object identity should be "is not"
 # E721 do not compare types, use "isinstance()"
 # E741 do not use variables named "l", "O", or "I"
@@ -87,4 +88,4 @@ elif PYTHONWARNINGS="ignore" flake8 --version | grep -q "Python 2"; then
     exit 0
 fi
 
-PYTHONWARNINGS="ignore" flake8 --ignore=B,C,E,F,I,N,W --select=E101,E112,E113,E115,E116,E125,E129,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E714,E721,E741,E742,E743,E901,E902,F401,F402,F403,F404,F405,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 "${@:-.}"
+PYTHONWARNINGS="ignore" flake8 --ignore=B,C,E,F,I,N,W --select=E101,E112,E113,E115,E116,E125,E129,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E711,E714,E721,E741,E742,E743,E901,E902,F401,F402,F403,F404,F405,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 "${@:-.}"