test: Disable several (sub)tests with cli

Reason for each test:
wallet_labels.py: uses createmultiwallet, which is currently not
compatible with cli
rpc_whitelist.py: Relies on direct RPC calls
wallet_encryption.py: Null characters cannot be passed to
suprocess.Popen, which is used to send the commands to
bitcoin-cli.

test/functional/rpc_whitelist.py

@@ -33,6 +33,7 @@ class RPCWhitelistTest(BitcoinTestFramework):
 
     def set_test_params(self):
         self.num_nodes = 1
+        self.supports_cli = False
 
     def run_test(self):
         # 0 => Username

test/functional/wallet_encryption.py

@@ -90,14 +90,15 @@ class WalletEncryptionTest(BitcoinTestFramework):
         assert_equal(actual_time, expected_time)
         self.nodes[0].walletlock()
 
-        # Test passphrase with null characters
-        passphrase_with_nulls = "Phrase\0With\0Nulls"
-        self.nodes[0].walletpassphrasechange(passphrase2, passphrase_with_nulls)
-        # walletpassphrasechange should not stop at null characters
-        assert_raises_rpc_error(-14, "wallet passphrase entered was incorrect", self.nodes[0].walletpassphrase, passphrase_with_nulls.partition("\0")[0], 10)
-        with WalletUnlock(self.nodes[0], passphrase_with_nulls):
-            sig = self.nodes[0].signmessage(address, msg)
-            assert self.nodes[0].verifymessage(address, sig, msg)
+        if not self.options.usecli: # can't be done with the test framework for cli since subprocess.Popen doesn't allow null characters
+            # Test passphrase with null characters
+            passphrase_with_nulls = "Phrase\0With\0Nulls"
+            self.nodes[0].walletpassphrasechange(passphrase2, passphrase_with_nulls)
+            # walletpassphrasechange should not stop at null characters
+            assert_raises_rpc_error(-14, "wallet passphrase entered was incorrect", self.nodes[0].walletpassphrase, passphrase_with_nulls.partition("\0")[0], 10)
+            with WalletUnlock(self.nodes[0], passphrase_with_nulls):
+                sig = self.nodes[0].signmessage(address, msg)
+                assert self.nodes[0].verifymessage(address, sig, msg)
 
         self.log.info("Test that wallets without private keys cannot be encrypted")
         self.nodes[0].createwallet(wallet_name="noprivs", disable_private_keys=True)

test/functional/wallet_send.py

@@ -29,6 +29,7 @@ class WalletSendTest(BitcoinTestFramework):
         self.num_nodes = 2
         # whitelist peers to speed up tx relay / mempool sync
         self.noban_tx_relay = True
+        self.supports_cli = False
         self.extra_args = [
             ["-walletrbf=1"],
             ["-walletrbf=1"]