test/cql-pytest: allow "run-cassandra" without building Scylla

Before this patch, all scripts which use test/cql-pytest/run.py
looked for the Scylla executable as their first step. This is usually
the right thing to do, except in two cases where Scylla is *not* needed:

1. The script test/cql-pytest/run-cassandra.
2. The script test/alternator/run with the "--aws" option.

So in this patch we change run.py to only look for Scylla when actually
needed (the find_scylla() function is called). In both cases mentioned
above, find_scylla() will never get called and the script can work even
if Scylla was never built.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>

Closes #13010

test/alternator/run

@@ -21,7 +21,7 @@ if '--aws' in sys.argv:
 import urllib3
 urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
 
-print('Scylla is: ' + run.scylla + '.')
+print('Scylla is: ' + run.find_scylla() + '.')
 
 # If the "--raft" option is given, switch to the experimental Raft-based
 # implementation of schema operations. When the experimental feature becomes

test/cql-pytest/run

@@ -4,7 +4,7 @@ import sys
 
 import run   # run.py in this directory
 
-print('Scylla is: ' + run.scylla + '.')
+print('Scylla is: ' + run.find_scylla() + '.')
 
 ssl = '--ssl' in sys.argv
 if ssl:

test/cql-pytest/run.py

@@ -162,17 +162,24 @@ import ssl
 # next to the location of this script, but this can be overridden by setting
 # a SCYLLA environment variable:
 source_path = os.path.realpath(os.path.join(__file__, '../../..'))
+scylla = None
 def find_scylla():
-    scyllas = glob.glob(os.path.join(source_path, 'build/*/scylla'))
-    if not scyllas:
-        print("Can't find a Scylla executable in {}.\nPlease build Scylla or set SCYLLA to the path of a Scylla executable.".format(source_path))
+    global scylla
+    global source_path
+    if scylla:
+        return scylla
+    if os.getenv('SCYLLA'):
+        scylla = os.path.abspath(os.getenv('SCYLLA'))
+    else:
+        scyllas = glob.glob(os.path.join(source_path, 'build/*/scylla'))
+        if not scyllas:
+            print("Can't find a Scylla executable in {}.\nPlease build Scylla or set SCYLLA to the path of a Scylla executable.".format(source_path))
+            exit(1)
+        scylla = max(scyllas, key=os.path.getmtime)
+    if not os.access(scylla, os.X_OK):
+        print("Cannot execute '{}'.\nPlease set SCYLLA to the path of a Scylla executable.".format(scylla))
         exit(1)
-    return max(scyllas, key=os.path.getmtime)
-
-scylla = os.path.abspath(os.getenv('SCYLLA') or find_scylla())
-if not os.access(scylla, os.X_OK):
-    print("Cannot execute '{}'.\nPlease set SCYLLA to the path of a Scylla executable.".format(scylla))
-    exit(1)
+    return scylla
 
 def run_scylla_cmd(pid, dir):
     ip = pid_to_ip(pid)

test/redis/run

@@ -6,7 +6,7 @@ import run
 
 import redis
 
-print('Scylla is: ' + run.scylla + '.')
+print('Scylla is: ' + run.find_scylla() + '.')
 
 REDIS_PORT = 6379
 

test/rest_api/run

@@ -6,7 +6,7 @@ import sys
 sys.path.insert(1, sys.path[0] + '/../cql-pytest')
 import run
 
-print('Scylla is: ' + run.scylla + '.')
+print('Scylla is: ' + run.find_scylla() + '.')
 
 ssl = '--ssl' in sys.argv
 if ssl:

test/scylla-gdb/run

@@ -8,7 +8,7 @@ import subprocess
 sys.path.insert(1, sys.path[0] + '/../cql-pytest')
 import run
 
-print('Scylla is: ' + run.scylla + '.')
+print('Scylla is: ' + run.find_scylla() + '.')
 
 # Gdb will only work if the executable was built with debug symbols
 # (e.g., Scylla's release or debug build modes mode, but not dev mode).