Don't try and run the interface_bitcoin_cli.py test when bitcoin-cli isn't available.
stdout:
2019-11-17T01:51:41.623000Z TestFramework (INFO): Initializing test directory /var/folders/z2/cn877pxd3czdfh47mfkmbwgm0000gn/T/test_runner_₿_🏃_20191116_205141/interface_bitcoin_cli_0
2019-11-17T01:51:41.890000Z TestFramework (ERROR): Unexpected exception caught during testing
Traceback (most recent call last):
File "/Users/michael/github/bitcoin/test/functional/test_framework/test_framework.py", line 111, in main
self.run_test()
File "/Users/michael/github/bitcoin/test/functional/interface_bitcoin_cli.py", line 18, in run_test
cli_response = self.nodes[0].cli("-version").send_cli()
File "/Users/michael/github/bitcoin/test/functional/test_framework/test_node.py", line 528, in send_cli
process = subprocess.Popen(p_args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
File "/Users/michael/.pyenv/versions/3.5.6/lib/python3.5/subprocess.py", line 676, in __init__
restore_signals, start_new_session)
File "/Users/michael/.pyenv/versions/3.5.6/lib/python3.5/subprocess.py", line 1289, in _execute_child
raise child_exception_type(errno_num, err_msg)
FileNotFoundError: [Errno 2] No such file or directory: '/Users/michael/github/bitcoin/src/bitcoin-cli'