diff --git a/tests/Pipfile b/tests/Pipfile
index 321872ecd43..4c810ba1fc8 100644
--- a/tests/Pipfile
+++ b/tests/Pipfile
@@ -35,6 +35,7 @@ dnslib = "*"
 requests = "*"
 gunicorn = "*"
 httpbin = "*"
+psutil = "*"
 
 # Keep init.cli.ext updated with this required microserver version.
 microserver = ">=1.0.6"
diff --git a/tests/gold_tests/basic/deny0.test.py b/tests/gold_tests/basic/deny0.test.py
index 285ad4c0773..ecb9f486ae0 100644
--- a/tests/gold_tests/basic/deny0.test.py
+++ b/tests/gold_tests/basic/deny0.test.py
@@ -18,6 +18,8 @@
 #  limitations under the License.
 
 import os
+import sys
+
 Test.Summary = '''
 Test that Trafficserver rejects requests for host 0
 '''
@@ -61,10 +63,13 @@ def buildMetaTest(testName, requestString):
         tr.Processes.Default.StartBefore(ts)
         tr.Processes.Default.StartBefore(redirect_serv, ready=When.PortOpen(redirect_serv.Variables.Port))
         tr.Processes.Default.StartBefore(dns)
-    with open(os.path.join(data_path, tr.Name), 'w') as f:
+
+    requestCommandPath = os.path.join(data_path, tr.Name)
+    with open(requestCommandPath, 'w') as f:
         f.write(requestString)
-    tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | head -1".format(
-        ts.Variables.port, os.path.join(data_dirname, tr.Name))
+    tr.Processes.Default.Command = \
+        (f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} "
+         f"{requestCommandPath} | head -1")
     tr.ReturnCode = 0
     tr.Processes.Default.Streams.stdout = gold_filepath
     tr.StillRunningAfter = ts
diff --git a/tests/gold_tests/h2/http2.test.py b/tests/gold_tests/h2/http2.test.py
index e6d2801ae35..38476191d61 100644
--- a/tests/gold_tests/h2/http2.test.py
+++ b/tests/gold_tests/h2/http2.test.py
@@ -17,6 +17,8 @@
 #  limitations under the License.
 
 import os
+import sys
+
 Test.Summary = '''
 Test a basic remap of a http/2 connection
 '''
@@ -143,7 +145,7 @@
 
 # Test Case 1:  basic H2 interaction
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 h2client.py -p {0}'.format(ts.Variables.ssl_port)
+tr.Processes.Default.Command = f'{sys.executable} h2client.py -p {ts.Variables.ssl_port}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(server)
 tr.Processes.Default.StartBefore(Test.Processes.ts)
@@ -152,14 +154,14 @@
 
 # Test Case 2: Make sure all the big file gets back.  Regression test for issue 1646
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 h2bigclient.py -p {0}'.format(ts.Variables.ssl_port)
+tr.Processes.Default.Command = f'{sys.executable} h2bigclient.py -p {ts.Variables.ssl_port}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.stdout = "gold/bigfile.gold"
 tr.StillRunningAfter = server
 
 # Test Case 3: Chunked content
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 h2chunked.py -p {0}  -u /test2'.format(ts.Variables.ssl_port)
+tr.Processes.Default.Command = f'{sys.executable} h2chunked.py -p {ts.Variables.ssl_port}  -u /test2'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.stdout = "gold/chunked.gold"
 tr.StillRunningAfter = server
@@ -168,15 +170,16 @@
 # Test Case 4: Multiple request
 # client_path = os.path.join(Test.Variables.AtsTestToolsDir, 'traffic-replay/')
 # tr = Test.AddTestRun()
-# tr.Processes.Default.Command = "python3 {0} -type {1} -log_dir {2} -port {3} -host '127.0.0.1' -s_port {4} -v -colorize False".format(
-#     client_path, 'h2', server.Variables.DataDir, ts.Variables.port, ts.Variables.ssl_port)
+# tr.Processes.Default.Command = \
+#     (f"{sys.executable} {client_path} -type h2 -log_dir {server.Variables.DataDir} "
+#      f"-port {ts.Variables.port} -host '127.0.0.1' -s_port {ts.Variables.ssl_port} -v -colorize False")
 # tr.Processes.Default.ReturnCode = 0
 # tr.Processes.Default.Streams.stdout = "gold/replay.gold"
 # tr.StillRunningAfter = server
 
 # Test Case 5: h2_active_timeout
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 h2active_timeout.py -p {0} -d 4'.format(ts.Variables.ssl_port)
+tr.Processes.Default.Command = f'{sys.executable} h2active_timeout.py -p {ts.Variables.ssl_port} -d 4'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = "gold/active_timeout.gold"
 tr.StillRunningAfter = server
diff --git a/tests/gold_tests/h2/httpbin.test.py b/tests/gold_tests/h2/httpbin.test.py
index ff8eb95a712..147b6551f32 100644
--- a/tests/gold_tests/h2/httpbin.test.py
+++ b/tests/gold_tests/h2/httpbin.test.py
@@ -17,6 +17,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 # ----
 # Setup Test
@@ -75,8 +76,8 @@
 Test.Disk.File(os.path.join(ts.Variables.LOGDIR, 'access.log'), exists=True, content='gold/httpbin_access.gold')
 
 # TODO: when httpbin 0.8.0 or later is released, remove below json pretty print hack
-json_printer = '''
-python3 -c "import sys,json; print(json.dumps(json.load(sys.stdin), indent=2, separators=(',', ': ')))"
+json_printer = f'''
+{sys.executable} -c "import sys,json; print(json.dumps(json.load(sys.stdin), indent=2, separators=(',', ': ')))"
 '''
 
 # ----
diff --git a/tests/gold_tests/headers/domain-blacklist-30x.test.py b/tests/gold_tests/headers/domain-blacklist-30x.test.py
index 275c3425890..0280ea0b8f6 100644
--- a/tests/gold_tests/headers/domain-blacklist-30x.test.py
+++ b/tests/gold_tests/headers/domain-blacklist-30x.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Tests 30x responses are returned for matching domains
@@ -56,57 +57,51 @@
 Test.Setup.Copy(os.path.join(os.pardir, os.pardir, 'tools', 'tcp_client.py'))
 Test.Setup.Copy('data')
 
-redirect301tr = Test.AddTestRun("Test domain {0}".format(REDIRECT_301_HOST))
+redirect301tr = Test.AddTestRun(f"Test domain {REDIRECT_301_HOST}")
 redirect301tr.Processes.Default.StartBefore(Test.Processes.ts)
 redirect301tr.StillRunningAfter = ts
-redirect301tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(REDIRECT_301_HOST))
+redirect301tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{REDIRECT_301_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 redirect301tr.Processes.Default.TimeOut = 5  # seconds
 redirect301tr.Processes.Default.ReturnCode = 0
 redirect301tr.Processes.Default.Streams.stdout = "redirect301_get.gold"
 
-redirect302tr = Test.AddTestRun("Test domain {0}".format(REDIRECT_302_HOST))
+redirect302tr = Test.AddTestRun(f"Test domain {REDIRECT_302_HOST}")
 redirect302tr.StillRunningBefore = ts
 redirect302tr.StillRunningAfter = ts
-redirect302tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(REDIRECT_302_HOST))
+redirect302tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{REDIRECT_302_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 redirect302tr.Processes.Default.TimeOut = 5  # seconds
 redirect302tr.Processes.Default.ReturnCode = 0
 redirect302tr.Processes.Default.Streams.stdout = "redirect302_get.gold"
 
 
-redirect307tr = Test.AddTestRun("Test domain {0}".format(REDIRECT_307_HOST))
+redirect307tr = Test.AddTestRun(f"Test domain {REDIRECT_307_HOST}")
 redirect302tr.StillRunningBefore = ts
 redirect307tr.StillRunningAfter = ts
-redirect307tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(REDIRECT_307_HOST))
+redirect307tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{REDIRECT_307_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 redirect307tr.Processes.Default.TimeOut = 5  # seconds
 redirect307tr.Processes.Default.ReturnCode = 0
 redirect307tr.Processes.Default.Streams.stdout = "redirect307_get.gold"
 
-redirect308tr = Test.AddTestRun("Test domain {0}".format(REDIRECT_308_HOST))
+redirect308tr = Test.AddTestRun(f"Test domain {REDIRECT_308_HOST}")
 redirect308tr.StillRunningBefore = ts
 redirect308tr.StillRunningAfter = ts
-redirect308tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(REDIRECT_308_HOST))
+redirect308tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{REDIRECT_308_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 redirect308tr.Processes.Default.TimeOut = 5  # seconds
 redirect308tr.Processes.Default.ReturnCode = 0
 redirect308tr.Processes.Default.Streams.stdout = "redirect308_get.gold"
 
-redirect0tr = Test.AddTestRun("Test domain {0}".format(REDIRECT_0_HOST))
+redirect0tr = Test.AddTestRun(f"Test domain {REDIRECT_0_HOST}")
 redirect0tr.StillRunningBefore = ts
 redirect0tr.StillRunningAfter = ts
-redirect0tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(REDIRECT_0_HOST))
+redirect0tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{REDIRECT_0_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 redirect0tr.Processes.Default.TimeOut = 5  # seconds
 redirect0tr.Processes.Default.ReturnCode = 0
 redirect0tr.Processes.Default.Streams.stdout = "redirect0_get.gold"
 
-passthroughtr = Test.AddTestRun("Test domain {0}".format(PASSTHRU_HOST))
+passthroughtr = Test.AddTestRun(f"Test domain {PASSTHRU_HOST}")
 passthroughtr.StillRunningBefore = ts
 passthroughtr.StillRunningAfter = ts
-passthroughtr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | grep -v '^Date: '| grep -v '^Server: ATS/'".\
-    format(ts.Variables.port, 'data/{0}_get.txt'.format(PASSTHRU_HOST))
+passthroughtr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{PASSTHRU_HOST}_get.txt | grep -v '^Date: '| grep -v '^Server: ATS/'"
 passthroughtr.Processes.Default.TimeOut = 5  # seconds
 passthroughtr.Processes.Default.ReturnCode = 0
 passthroughtr.Processes.Default.Streams.stdout = "passthrough_get.gold"
diff --git a/tests/gold_tests/headers/general-connection-failure-502.test.py b/tests/gold_tests/headers/general-connection-failure-502.test.py
index 4cb06c3b449..e0f28f56edd 100644
--- a/tests/gold_tests/headers/general-connection-failure-502.test.py
+++ b/tests/gold_tests/headers/general-connection-failure-502.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Test response when connection to origin fails
@@ -39,7 +40,8 @@
 tr = Test.AddTestRun()
 tr.Processes.Default.StartBefore(Test.Processes.ts)
 # Do not start the origin server: We wish to simulate connection refused while hopefully no one else uses this port.
-tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | sed -e '/^Date: /d' -e '/^Server: ATS\//d'"\
-    .format(ts.Variables.port, "www.connectfail502.test-get.txt")
+tr.Processes.Default.Command = \
+    (f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} www.connectfail502.test-get.txt | "
+     "sed -e '/^Date: /d' -e '/^Server: ATS\//d'")
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.stdout = 'general-connection-failure-502.gold'
diff --git a/tests/gold_tests/headers/http408.test.py b/tests/gold_tests/headers/http408.test.py
index e3c2d9cd697..c841bfafe77 100644
--- a/tests/gold_tests/headers/http408.test.py
+++ b/tests/gold_tests/headers/http408.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Check 408 response header for protocol stack data.
@@ -50,8 +51,8 @@
 tr = Test.AddTestRun()
 tr.Processes.Default.StartBefore(server)
 tr.Processes.Default.StartBefore(Test.Processes.ts)
-tr.Processes.Default.Command = 'python3 tcp_client.py 127.0.0.1 {0} {1} --delay-after-send {2}'\
-    .format(ts.Variables.port, 'data/{0}.txt'.format(HTTP_408_HOST), TIMEOUT + 2)
+DELAY = TIMEOUT + 2
+tr.Processes.Default.Command = f'{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} data/{HTTP_408_HOST}.txt --delay-after-send {DELAY}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.TimeOut = 10
 tr.Processes.Default.Streams.stdout = "http408.gold"
diff --git a/tests/gold_tests/logging/all_headers.test.py b/tests/gold_tests/logging/all_headers.test.py
index c5f6a930ece..45bb984108e 100644
--- a/tests/gold_tests/logging/all_headers.test.py
+++ b/tests/gold_tests/logging/all_headers.test.py
@@ -17,6 +17,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Test new "all headers" log fields
@@ -60,8 +61,8 @@
 
 # Configure comparison of "sanitized" log file with gold file at end of test.
 #
-Test.Disk.File(os.path.join(ts.Variables.LOGDIR, 'test_all_headers.log.san'),
-               exists=True, content='gold/test_all_headers.gold')
+sanitized_log_path = os.path.join(ts.Variables.LOGDIR, 'test_all_headers.log.san')
+Test.Disk.File(sanitized_log_path, exists=True, content='gold/test_all_headers.gold')
 
 
 def reallyLong():
@@ -94,10 +95,12 @@ def reallyLong():
 # Delay to allow TS to flush report to disk, then "sanitize" generated log.
 #
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 {0} {2} {4} | sh {1} > {3}'.format(
-    os.path.join(Test.TestDirectory, 'all_headers_sanitizer.py'),
-    os.path.join(Test.TestDirectory, 'all_headers_sanitizer.sh'),
-    os.path.join(ts.Variables.LOGDIR, 'test_all_headers.log'),
-    os.path.join(ts.Variables.LOGDIR, 'test_all_headers.log.san'),
-    server.Variables.Port)
+
+log_path = os.path.join(ts.Variables.LOGDIR, 'test_all_headers.log')
+sanitizer_python_script = os.path.join(Test.TestDirectory, 'all_headers_sanitizer.py')
+sanitizer_shell_script = os.path.join(Test.TestDirectory, 'all_headers_sanitizer.sh')
+
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {sanitizer_python_script} {log_path} {server.Variables.Port} | '
+     f'sh {sanitizer_shell_script} > {sanitized_log_path}')
 tr.Processes.Default.ReturnCode = 0
diff --git a/tests/gold_tests/logging/log_pipe.test.py b/tests/gold_tests/logging/log_pipe.test.py
index fae1bce366c..7488c4031ea 100644
--- a/tests/gold_tests/logging/log_pipe.test.py
+++ b/tests/gold_tests/logging/log_pipe.test.py
@@ -17,6 +17,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Test custom log file format
@@ -162,7 +163,7 @@ def get_ts(logging_config):
 tr.Setup.Copy(buffer_verifier)
 verify_buffer_size = tr.Processes.Process(
     "verify_buffer_size",
-    "python3 {} {} {}".format(buffer_verifier, pipe_path, pipe_size))
+    f"{sys.executable} {buffer_verifier} {pipe_path} {pipe_size}")
 verify_buffer_size.Return = 0
 verify_buffer_size.Streams.All += Testers.ContainsExpression(
     "Success",
diff --git a/tests/gold_tests/logging/new_log_flds.test.py b/tests/gold_tests/logging/new_log_flds.test.py
index c38da40f6f6..3a4e3ea2fb5 100644
--- a/tests/gold_tests/logging/new_log_flds.test.py
+++ b/tests/gold_tests/logging/new_log_flds.test.py
@@ -17,6 +17,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Test new log fields
@@ -117,7 +118,7 @@
 # Validate generated log.
 #
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 {0} < {1}'.format(
-    os.path.join(Test.TestDirectory, 'new_log_flds_observer.py'),
-    os.path.join(ts.Variables.LOGDIR, 'test_new_log_flds.log'))
+observer_script = os.path.join(Test.TestDirectory, 'new_log_flds_observer.py')
+log_path = os.path.join(ts.Variables.LOGDIR, 'test_new_log_flds.log')
+tr.Processes.Default.Command = f'{sys.executable} {observer_script} < {log_path}'
 tr.Processes.Default.ReturnCode = 0
diff --git a/tests/gold_tests/logging/sigusr2.test.py b/tests/gold_tests/logging/sigusr2.test.py
index a02c302dc07..fae67e051c4 100644
--- a/tests/gold_tests/logging/sigusr2.test.py
+++ b/tests/gold_tests/logging/sigusr2.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 
 TRAFFIC_MANAGER_PID_SCRIPT = 'ts_process_handler.py'
@@ -107,8 +108,8 @@ def get_sigusr2_signal_command(self):
         Return the command that will send a USR2 signal to the traffic manager
         process.
         """
-        return r"python3 {} --parent --signal SIGUSR2 {}".format(
-            TRAFFIC_MANAGER_PID_SCRIPT, self._ts_name)
+        return (f"{sys.executable} {TRAFFIC_MANAGER_PID_SCRIPT} --parent "
+                f"--signal SIGUSR2 {self._ts_name}")
 
 
 Test.Summary = '''
diff --git a/tests/gold_tests/pluginTest/combo_handler/combo_handler.test.py b/tests/gold_tests/pluginTest/combo_handler/combo_handler.test.py
index b4a5a3e2c44..d785bf53e31 100644
--- a/tests/gold_tests/pluginTest/combo_handler/combo_handler.test.py
+++ b/tests/gold_tests/pluginTest/combo_handler/combo_handler.test.py
@@ -17,6 +17,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Test combo_handler plugin
@@ -36,7 +37,7 @@
 
 def data_file(data):
     global _data_file__file_count
-    file_path = Test.RunDirectory + "/tcp_client_in_{}".format(_data_file__file_count)
+    file_path = Test.RunDirectory + f"/tcp_client_in_{_data_file__file_count}"
     _data_file__file_count += 1
     with open(file_path, "x") as f:
         f.write(data)
@@ -47,7 +48,7 @@ def data_file(data):
 
 
 def tcp_client_cmd(host, port, file_path):
-    return "python3 {}/tcp_client.py {} {} {}".format(Test.Variables.AtsTestToolsDir, host, port, file_path)
+    return f"{sys.executable} {Test.Variables.AtsTestToolsDir}/tcp_client.py {host} {port} {file_path}"
 
 # Function to return command (string) to run tcp_client.py tool.  'host' and 'port' are the first two parameters to tcp_client.
 # 'data' is the data to put in the data file input to tcp_client.
@@ -100,10 +101,10 @@ def add_server_obj(content_type, path):
     'map http://xyz/ http://127.0.0.1/ @plugin=combo_handler.so'
 )
 ts.Disk.remap_config.AddLine(
-    'map http://localhost/127.0.0.1/ http://127.0.0.1:{}/'.format(server.Variables.Port)
+    f'map http://localhost/127.0.0.1/ http://127.0.0.1:{server.Variables.Port}/'
 )
 ts.Disk.remap_config.AddLine(
-    'map http://localhost/sub/ http://127.0.0.1:{}/sub/'.format(server.Variables.Port)
+    f'map http://localhost/sub/ http://127.0.0.1:{server.Variables.Port}/sub/'
 )
 
 # Configure the combo_handler's configuration file.
diff --git a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump.test.py b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump.test.py
index 93db6d59f83..1aa57e47f1a 100644
--- a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump.test.py
+++ b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Verify traffic_dump functionality.
@@ -27,6 +28,8 @@
     Condition.PluginExists('traffic_dump.so'),
 )
 
+schema_path = os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json')
+
 # Configure the origin server.
 replay_file = "replay/traffic_dump.yaml"
 server = Test.MakeVerifierServerProcess(
@@ -50,10 +53,10 @@
     'proxy.config.diags.debug.tags': 'traffic_dump',
     'proxy.config.http.insert_age_in_response': 0,
 
-    'proxy.config.ssl.server.cert.path': '{0}'.format(ts.Variables.SSLDir),
-    'proxy.config.ssl.server.private_key.path': '{0}'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.server.cert.path': ts.Variables.SSLDir,
+    'proxy.config.ssl.server.private_key.path': ts.Variables.SSLDir,
     'proxy.config.url_remap.pristine_host_hdr': 1,
-    'proxy.config.ssl.CA.cert.filename': '{0}/signer.pem'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.CA.cert.filename': f'{ts.Variables.SSLDir}/signer.pem',
     'proxy.config.exec_thread.autoconfig.scale': 1.0,
     'proxy.config.http.host_sni_policy': 2,
     'proxy.config.ssl.TLSv1_3': 0,
@@ -65,19 +68,19 @@
 )
 
 ts.Disk.remap_config.AddLine(
-    'map https://www.client_only_tls.com/ http://127.0.0.1:{0}'.format(server.Variables.http_port)
+    f'map https://www.client_only_tls.com/ http://127.0.0.1:{server.Variables.http_port}'
 )
 ts.Disk.remap_config.AddLine(
-    'map https://www.tls.com/ https://127.0.0.1:{0}'.format(server.Variables.https_port)
+    f'map https://www.tls.com/ https://127.0.0.1:{server.Variables.https_port}'
 )
 ts.Disk.remap_config.AddLine(
-    'map / http://127.0.0.1:{0}'.format(server.Variables.http_port)
+    f'map / http://127.0.0.1:{server.Variables.http_port}'
 )
 
 # Configure traffic_dump.
 ts.Disk.plugin_config.AddLine(
-    'traffic_dump.so --logdir {0} --sample 1 --limit 1000000000 '
-    '--sensitive-fields "cookie,set-cookie,x-request-1,x-request-2"'.format(replay_dir)
+    f'traffic_dump.so --logdir {replay_dir} --sample 1 --limit 1000000000 '
+    '--sensitive-fields "cookie,set-cookie,x-request-1,x-request-2"'
 )
 # Configure logging of transactions. This is helpful for the cache test below.
 ts.Disk.logging_yaml.AddLines(
@@ -96,7 +99,7 @@
     "loading plugin.*traffic_dump.so",
     "Verify the traffic_dump plugin got loaded.")
 ts.Streams.stderr = Testers.ContainsExpression(
-    "Initialized with log directory: {0}".format(replay_dir),
+    f"Initialized with log directory: {replay_dir}",
     "Verify traffic_dump initialized with the configured directory.")
 ts.Streams.stderr += Testers.ContainsExpression(
     "Initialized with sample pool size 1 bytes and disk limit 1000000000 bytes",
@@ -158,13 +161,9 @@
     "--sensitive-fields x-request-2 ")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 tr.Processes.Default.Command = \
-    ('python3 {0} {1} {2} {3} --client-http-version "1.1" '
-     '--client-protocols "{4}"'.format(
-         verify_replay,
-         os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-         replay_file_session_1,
-         sensitive_fields_arg,
-         http_protocols))
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_1} '
+     f'{sensitive_fields_arg} --client-http-version "1.1" '
+     f'--client-protocols "{http_protocols}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -173,12 +172,9 @@
 tr = Test.AddTestRun("Verify the json content of the second session")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 tr.Processes.Default.Command = \
-    ('python3 {0} {1} {2} {3} --client-http-version "1.1" '
-     '--request-target "/two"'.format(
-         verify_replay,
-         os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-         replay_file_session_2,
-         sensitive_fields_arg))
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_2} '
+     f'{sensitive_fields_arg} --client-http-version "1.1" '
+     '--request-target "/two"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -191,12 +187,9 @@
 tr = Test.AddTestRun("Verify the replay file has the explicit target.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 
-tr.Processes.Default.Command = "python3 {0} {1} {2} {3} --request-target '{4}'".format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_3,
-    sensitive_fields_arg,
-    "http://www.some.host.com/candy")
+tr.Processes.Default.Command = \
+    (f"{sys.executable} {verify_replay} {schema_path} {replay_file_session_3} {sensitive_fields_arg} "
+     "--request-target 'http://www.some.host.com/candy'")
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -211,12 +204,8 @@
 size_of_verify_replay_file = os.path.getsize(os.path.join(Test.TestDirectory, verify_replay))
 expected_body_size = 12345
 tr.Processes.Default.Command = \
-    "python3 {0} {1} {2} {3} --client-request-size {4}".format(
-        verify_replay,
-        os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-        replay_file_session_4,
-        sensitive_fields_arg,
-        expected_body_size)
+    (f"{sys.executable} {verify_replay} {schema_path} {replay_file_session_4} {sensitive_fields_arg} "
+     f"--client-request-size {expected_body_size}")
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -226,11 +215,9 @@
 #
 tr = Test.AddTestRun("Verify that the cached response's replay file looks appropriate.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --client-protocols "{3}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_6,
-    http_protocols)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_6} '
+     f'--client-protocols "{http_protocols}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -240,11 +227,9 @@
 #
 tr = Test.AddTestRun("Verify the dump file of two transactions in a session.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --client-protocols "{3}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_7,
-    http_protocols)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_7} '
+     f'--client-protocols "{http_protocols}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -256,12 +241,9 @@
 https_protocols = "tls,tcp,ip"
 client_tls_features = "sni:www.tls.com,proxy-verify-mode:0,proxy-provided-cert:true"
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --client-protocols "{3}" --client-tls-features "{4}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_8,
-    https_protocols,
-    client_tls_features)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_8} '
+     f'--client-protocols "{https_protocols}" --client-tls-features "{client_tls_features}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -270,12 +252,9 @@
 https_server_stack = "http,tls,tcp,ip"
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 server_tls_features = 'proxy-provided-cert:false,sni:www.tls.com,proxy-verify-mode:1'
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --server-protocols "{3}" --server-tls-features "{4}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_8,
-    https_server_stack,
-    server_tls_features)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_8} --server-protocols '
+     f'"{https_server_stack}" --server-tls-features "{server_tls_features}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -287,25 +266,18 @@
 h2_protocols = "http,tls,tcp,ip"
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 tr.Processes.Default.Command = \
-    ('python3 {0} {1} {2} --client-http-version "2" '
-     '--client-protocols "{3}" --client-tls-features "{4}"'.format(
-         verify_replay,
-         os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-         replay_file_session_9,
-         h2_protocols,
-         client_tls_features))
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_9} '
+     f'--client-http-version "2" --client-protocols "{h2_protocols}" '
+     f'--client-tls-features "{client_tls_features}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
 
 tr = Test.AddTestRun("Verify the server HTTP/2 protocol stack.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --server-protocols "{3}" --server-tls-features "{4}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_9,
-    https_server_stack,
-    server_tls_features)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_9} '
+     f'--server-protocols "{https_server_stack}" --server-tls-features "{server_tls_features}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -315,11 +287,9 @@
 #
 tr = Test.AddTestRun("Verify the client TLS protocol stack.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --client-http-version "1.1" --client-protocols "{3}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_10,
-    https_protocols)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_10} '
+     f'--client-http-version "1.1" --client-protocols "{https_protocols}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
@@ -327,11 +297,9 @@
 tr = Test.AddTestRun("Verify the server HTTP protocol stack.")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 http_server_stack = "http,tcp,ip"
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --server-protocols "{3}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_10,
-    http_server_stack)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_10} '
+     f'--server-protocols "{http_server_stack}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
diff --git a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_http3.test.py b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_http3.test.py
index b3c31b09206..c4c9bbfaaed 100644
--- a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_http3.test.py
+++ b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_http3.test.py
@@ -18,6 +18,8 @@
 #  limitations under the License.
 
 import os
+import sys
+
 Test.Summary = '''
 Verify traffic_dump HTTP/3 functionality.
 '''
@@ -30,6 +32,8 @@
     Condition.true("Skip this test until the TS_EVENT_HTTP_SSN are supported for QUIC connections."),
 )
 
+schema_path = os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json')
+
 # Configure the origin server.
 replay_file = "replay/http3.yaml"
 server = Test.MakeVerifierServerProcess(
@@ -53,10 +57,10 @@
 
     'proxy.config.quic.qlog_dir': qlog_dir,
 
-    'proxy.config.ssl.server.cert.path': '{0}'.format(ts.Variables.SSLDir),
-    'proxy.config.ssl.server.private_key.path': '{0}'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.server.cert.path': ts.Variables.SSLDir,
+    'proxy.config.ssl.server.private_key.path': ts.Variables.SSLDir,
     'proxy.config.url_remap.pristine_host_hdr': 1,
-    'proxy.config.ssl.CA.cert.filename': '{0}/signer.pem'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.CA.cert.filename': f'{ts.Variables.SSLDir}/signer.pem',
     'proxy.config.exec_thread.autoconfig.scale': 1.0,
     'proxy.config.http.host_sni_policy': 2,
     'proxy.config.ssl.client.verify.server.policy': 'PERMISSIVE',
@@ -67,13 +71,13 @@
 )
 
 ts.Disk.remap_config.AddLine(
-    'map https://www.client_only_tls.com/ http://127.0.0.1:{0}'.format(server.Variables.http_port)
+    f'map https://www.client_only_tls.com/ http://127.0.0.1:{server.Variables.http_port}'
 )
 ts.Disk.remap_config.AddLine(
-    'map https://www.tls.com/ https://127.0.0.1:{0}'.format(server.Variables.https_port)
+    f'map https://www.tls.com/ https://127.0.0.1:{server.Variables.https_port}'
 )
 ts.Disk.remap_config.AddLine(
-    'map / http://127.0.0.1:{0}'.format(server.Variables.http_port)
+    f'map / http://127.0.0.1:{server.Variables.http_port}'
 )
 
 # Configure traffic_dump.
@@ -141,13 +145,9 @@
     "--sensitive-fields x-request-2 ")
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
 tr.Processes.Default.Command = \
-    ('python3 {0} {1} {2} {3} --client-http-version "3" '
-     '--client-protocols "{4}"'.format(
-         verify_replay,
-         os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-         replay_file_session_1,
-         sensitive_fields_arg,
-         http_protocols))
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_1} '
+     f'{sensitive_fields_arg} --client-http-version "3" '
+     f'--client-protocols "{http_protocols}"')
 tr.Processes.Default.ReturnCode = 0
 tr.StillRunningAfter = server
 tr.StillRunningAfter = ts
diff --git a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_ip_filter.test.py b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_ip_filter.test.py
index 9cc61b2c6b0..12eeae0e15c 100644
--- a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_ip_filter.test.py
+++ b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_ip_filter.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Verify traffic_dump IP filter functionality.
@@ -64,7 +65,7 @@ def get_common_ats_process(name, plugin_command, replay_exists):
 # Common verification variables.
 verify_replay = "verify_replay.py"
 schema = os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json')
-verify_command_prefix = f'python3 {verify_replay} {schema}'
+verify_command_prefix = f'{sys.executable} {verify_replay} {schema}'
 
 #
 # Test 1: Verify -4 works for a specified address.
diff --git a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_response_body.test.py b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_response_body.test.py
index a1fda20b0af..61538d13b71 100644
--- a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_response_body.test.py
+++ b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_response_body.test.py
@@ -18,6 +18,7 @@
 #  limitations under the License.
 
 import os
+import sys
 
 Test.Summary = '''
 Verify traffic_dump response body functionality.
@@ -99,7 +100,7 @@
 # Common verification variables.
 verify_replay = "verify_replay.py"
 schema = os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json')
-verify_command_prefix = f'python3 {verify_replay} {schema}'
+verify_command_prefix = f'{sys.executable} {verify_replay} {schema}'
 
 #
 # Verify a response without a body is dumped correctly.
diff --git a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_sni_filter.test.py b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_sni_filter.test.py
index 03a52b87b42..3f8b89c1b89 100644
--- a/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_sni_filter.test.py
+++ b/tests/gold_tests/pluginTest/traffic_dump/traffic_dump_sni_filter.test.py
@@ -18,6 +18,8 @@
 #  limitations under the License.
 
 import os
+import sys
+
 Test.Summary = '''
 Verify traffic_dump functionality.
 '''
@@ -26,6 +28,7 @@
     Condition.PluginExists('traffic_dump.so'),
 )
 
+schema_path = os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json')
 replay_file = "replay/various_sni.yaml"
 server = Test.MakeVerifierServerProcess(
     "server-various-sni", replay_file,
@@ -43,10 +46,10 @@
     'proxy.config.diags.debug.enabled': 1,
     'proxy.config.diags.debug.tags': 'traffic_dump',
 
-    'proxy.config.ssl.server.cert.path': '{0}'.format(ts.Variables.SSLDir),
-    'proxy.config.ssl.server.private_key.path': '{0}'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.server.cert.path': ts.Variables.SSLDir,
+    'proxy.config.ssl.server.private_key.path': ts.Variables.SSLDir,
     'proxy.config.url_remap.pristine_host_hdr': 1,
-    'proxy.config.ssl.CA.cert.filename': '{0}/signer.pem'.format(ts.Variables.SSLDir),
+    'proxy.config.ssl.CA.cert.filename': f'{ts.Variables.SSLDir}/signer.pem',
     'proxy.config.exec_thread.autoconfig.scale': 1.0,
     'proxy.config.http.host_sni_policy': 2,
     'proxy.config.ssl.TLSv1_3': 0,
@@ -58,7 +61,7 @@
 )
 
 ts.Disk.remap_config.AddLine(
-    'map / https://127.0.0.1:{0}'.format(server.Variables.https_port)
+    f'map / https://127.0.0.1:{server.Variables.https_port}'
 )
 
 ts.Disk.sni_yaml.AddLines([
@@ -71,13 +74,13 @@
 # Configure traffic_dump's SNI filter to only dump connections with SNI bob.com.
 sni_filter = "bob.com"
 ts.Disk.plugin_config.AddLine(
-    'traffic_dump.so --logdir {0} --sample 1 --limit 1000000000 '
-    '--sni-filter "{1}"'.format(replay_dir, sni_filter)
+    f'traffic_dump.so --logdir {replay_dir} --sample 1 --limit 1000000000 '
+    f'--sni-filter "{sni_filter}"'
 )
 
 # Set up trafficserver expectations.
 ts.Streams.stderr += Testers.ContainsExpression(
-    "Filtering to only dump connections with SNI: {}".format(sni_filter),
+    f"Filtering to only dump connections with SNI: {sni_filter}",
     "Verify filtering for the expected SNI.")
 
 ts.Streams.stderr += Testers.ContainsExpression(
@@ -117,10 +120,7 @@
 session_1_tls_features = 'sni:bob.com,proxy-verify-mode:0,proxy-provided-cert:true'
 verify_replay = "verify_replay.py"
 tr.Setup.CopyAs(verify_replay, Test.RunDirectory)
-tr.Processes.Default.Command = 'python3 {0} {1} {2} --client-protocols "{3}" --client-tls-features "{4}"'.format(
-    verify_replay,
-    os.path.join(Test.Variables.AtsTestToolsDir, 'lib', 'replay_schema.json'),
-    replay_file_session_1,
-    session_1_protocols,
-    session_1_tls_features)
+tr.Processes.Default.Command = \
+    (f'{sys.executable} {verify_replay} {schema_path} {replay_file_session_1} '
+     f'--client-protocols "{session_1_protocols}" --client-tls-features "{session_1_tls_features}"')
 tr.Processes.Default.ReturnCode = 0
diff --git a/tests/gold_tests/pluginTest/xdebug/x_cache_info/x_cache_info.test.py b/tests/gold_tests/pluginTest/xdebug/x_cache_info/x_cache_info.test.py
index 892297bb6dd..5d6529b1846 100644
--- a/tests/gold_tests/pluginTest/xdebug/x_cache_info/x_cache_info.test.py
+++ b/tests/gold_tests/pluginTest/xdebug/x_cache_info/x_cache_info.test.py
@@ -14,6 +14,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
+
 Test.Summary = '''
 Test xdebug plugin X-Cache-Info header
 '''
@@ -57,7 +59,7 @@
 def sendMsg(msgFile):
     global started
     tr = Test.AddTestRun()
-    tr.Processes.Default.Command = f"( python3 tools/tcp_client.py 127.0.0.1 {ts.Variables.port} {msgFile}.in ; echo '======' ) | sed 's/:{server.Variables.Port}/:SERVER_PORT/' >>  out.log 2>&1"
+    tr.Processes.Default.Command = f"( {sys.executable} tools/tcp_client.py 127.0.0.1 {ts.Variables.port} {msgFile}.in ; echo '======' ) | sed 's/:{server.Variables.Port}/:SERVER_PORT/' >>  out.log 2>&1"
     tr.Processes.Default.ReturnCode = 0
 
     if not started:
diff --git a/tests/gold_tests/pluginTest/xdebug/x_effective_url/x_effective_url.test.py b/tests/gold_tests/pluginTest/xdebug/x_effective_url/x_effective_url.test.py
index ed1c3b54300..29c09c51605 100644
--- a/tests/gold_tests/pluginTest/xdebug/x_effective_url/x_effective_url.test.py
+++ b/tests/gold_tests/pluginTest/xdebug/x_effective_url/x_effective_url.test.py
@@ -14,6 +14,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
+
 Test.Summary = '''
 Test xdebug plugin X-Effective header
 '''
@@ -61,10 +63,8 @@ def sendMsg(msgFile):
 
     tr = Test.AddTestRun()
     tr.Processes.Default.Command = (
-        "( python3 {}/tcp_client.py 127.0.0.1 {} {}/{}.in".format(
-            Test.RunDirectory, ts.Variables.port, Test.TestDirectory, msgFile) +
-        " ; echo '======' ) | sed 's/:{}/:SERVER_PORT/' >>  {}/out.log 2>&1 ".format(
-            server.Variables.Port, Test.RunDirectory)
+        f"( {sys.executable} {Test.RunDirectory}/tcp_client.py 127.0.0.1 {ts.Variables.port} {Test.TestDirectory}/{msgFile}.in"
+        f" ; echo '======' ) | sed 's/:{server.Variables.Port}/:SERVER_PORT/' >>  {Test.RunDirectory}/out.log 2>&1 "
     )
     tr.Processes.Default.ReturnCode = 0
 
diff --git a/tests/gold_tests/pluginTest/xdebug/x_remap/x_remap.test.py b/tests/gold_tests/pluginTest/xdebug/x_remap/x_remap.test.py
index f5ee5df0eea..a4dcee01622 100644
--- a/tests/gold_tests/pluginTest/xdebug/x_remap/x_remap.test.py
+++ b/tests/gold_tests/pluginTest/xdebug/x_remap/x_remap.test.py
@@ -14,6 +14,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
+
 Test.Summary = '''
 Test xdebug plugin X-Remap, Probe and fwd headers
 '''
@@ -59,10 +61,8 @@ def sendMsg(msgFile):
 
     tr = Test.AddTestRun()
     tr.Processes.Default.Command = (
-        "( python3 {}/tcp_client.py 127.0.0.1 {} {}/{}.in".format(
-            Test.RunDirectory, ts.Variables.port, Test.TestDirectory, msgFile) +
-        " ; echo '======' ) | sed 's/:{}/:SERVER_PORT/' >>  {}/out.log 2>&1 ".format(
-            server.Variables.Port, Test.RunDirectory)
+        f"( {sys.executable} {Test.RunDirectory}/tcp_client.py 127.0.0.1 {ts.Variables.port} {Test.TestDirectory}/{msgFile}.in"
+        f" ; echo '======' ) | sed 's/:{server.Variables.Port}/:SERVER_PORT/' >>  {Test.RunDirectory}/out.log 2>&1 "
     )
     tr.Processes.Default.ReturnCode = 0
 
diff --git a/tests/gold_tests/redirect/redirect.test.py b/tests/gold_tests/redirect/redirect.test.py
index bd586898d08..01777dc3738 100644
--- a/tests/gold_tests/redirect/redirect.test.py
+++ b/tests/gold_tests/redirect/redirect.test.py
@@ -18,6 +18,8 @@
 #  limitations under the License.
 
 import os
+import sys
+
 Test.Summary = '''
 Test redirection
 '''
@@ -71,10 +73,10 @@
 # Here and below: spaces are deliberately omitted from the test run names because autest creates directories using these names.
 tr = Test.AddTestRun("FollowsRedirectWithAbsoluteLocationURI")
 # Here and below: because autest's Copy does not behave like standard cp, it's easiest to write all of our files out and copy last.
-with open(os.path.join(data_path, tr.Name), 'w') as f:
+command_path = os.path.join(data_path, tr.Name)
+with open(command_path, 'w') as f:
     f.write('GET /redirect HTTP/1.1\r\nHost: iwillredirect.test:{port}\r\n\r\n'.format(port=redirect_serv.Variables.Port))
-tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | egrep -v '^(Date: |Server: ATS/)'".format(
-    ts.Variables.port, os.path.join(data_dirname, tr.Name))
+tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} {command_path} | egrep -v '^(Date: |Server: ATS/)'"
 tr.Processes.Default.StartBefore(ts)
 tr.Processes.Default.StartBefore(redirect_serv)
 tr.Processes.Default.StartBefore(dest_serv)
@@ -92,11 +94,11 @@
 redirect_serv.addResponse("sessionfile.log", redirect_request_header, redirect_response_header)
 
 tr = Test.AddTestRun("FollowsRedirectWithRelativeLocationURI")
-with open(os.path.join(data_path, tr.Name), 'w') as f:
+command_path = os.path.join(data_path, tr.Name)
+with open(command_path, 'w') as f:
     f.write(
         'GET /redirect-relative-path HTTP/1.1\r\nHost: iwillredirect.test:{port}\r\n\r\n'.format(port=redirect_serv.Variables.Port))
-tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | egrep -v '^(Date: |Server: ATS/)'".format(
-    ts.Variables.port, os.path.join(data_dirname, tr.Name))
+tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} {command_path} | egrep -v '^(Date: |Server: ATS/)'"
 tr.StillRunningAfter = ts
 tr.StillRunningAfter = redirect_serv
 tr.StillRunningAfter = dest_serv
@@ -111,11 +113,11 @@
 redirect_serv.addResponse("sessionfile.log", redirect_request_header, redirect_response_header)
 
 tr = Test.AddTestRun("FollowsRedirectWithRelativeLocationURIMissingLeadingSlash")
-with open(os.path.join(data_path, tr.Name), 'w') as f:
+command_path = os.path.join(data_path, tr.Name)
+with open(command_path, 'w') as f:
     f.write(
         'GET /redirect-relative-path-no-leading-slash HTTP/1.1\r\nHost: iwillredirect.test:{port}\r\n\r\n'.format(port=redirect_serv.Variables.Port))
-tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | egrep -v '^(Date: |Server: ATS/)'".format(
-    ts.Variables.port, os.path.join(data_dirname, tr.Name))
+tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} {command_path} | egrep -v '^(Date: |Server: ATS/)'"
 tr.StillRunningAfter = ts
 tr.StillRunningAfter = redirect_serv
 tr.StillRunningAfter = dest_serv
@@ -149,12 +151,12 @@
     redirect_serv.addResponse("sessionfile.log", redirect_request_header, redirect_response_header)
 
     tr = Test.AddTestRun("FollowsRedirect{0}".format(status))
-    with open(os.path.join(data_path, tr.Name), 'w') as f:
+    command_path = os.path.join(data_path, tr.Name)
+    with open(command_path, 'w') as f:
         f.write(('GET /redirect{0} HTTP/1.1\r\n'
                  'Host: iwillredirect.test:{1}\r\n\r\n').
                 format(status, redirect_serv.Variables.Port))
-    tr.Processes.Default.Command = "python3 tcp_client.py 127.0.0.1 {0} {1} | egrep -v '^(Date: |Server: ATS/)'".\
-        format(ts.Variables.port, os.path.join(data_dirname, tr.Name))
+    tr.Processes.Default.Command = f"{sys.executable} tcp_client.py 127.0.0.1 {ts.Variables.port} {command_path} | egrep -v '^(Date: |Server: ATS/)'"
     tr.StillRunningAfter = ts
     tr.StillRunningAfter = redirect_serv
     tr.StillRunningAfter = dest_serv
diff --git a/tests/gold_tests/redirect/redirect_actions.test.py b/tests/gold_tests/redirect/redirect_actions.test.py
index 5c1f49e481f..486b39af581 100644
--- a/tests/gold_tests/redirect/redirect_actions.test.py
+++ b/tests/gold_tests/redirect/redirect_actions.test.py
@@ -21,6 +21,8 @@
 import re
 import os
 import socket
+import sys
+
 Test.Summary = '''
 Test redirection behavior to invalid addresses
 '''
@@ -149,13 +151,17 @@ def makeTestCase(redirectTarget, expectedAction, scenario):
     origin.addResponse('sessionfile.log', request_header, response_header)
 
     # Generate the request data file.
-    with open(os.path.join(data_path, tr.Name), 'w') as f:
+    command_path = os.path.join(data_path, tr.Name)
+    with open(command_path, 'w') as f:
         f.write(('GET /redirect?config={0}&target={1} HTTP/1.1\r\n'
                  'Host: iwillredirect.test:{2}\r\n\r\n').
                 format(normConfig, normRedirectTarget, origin.Variables.Port))
     # Set the command with the appropriate URL.
-    tr.Processes.Default.Command = "bash -o pipefail -c 'python3 tcp_client.py 127.0.0.1 {0} {1} | head -n 1'".\
-        format(trafficservers[config].Variables.port, os.path.join(data_dirname, tr.Name))
+    port = trafficservers[config].Variables.port
+    dir_path = os.path.join(data_dirname, tr.Name)
+    tr.Processes.Default.Command = \
+        (f"bash -o pipefail -c '{sys.executable} tcp_client.py 127.0.0.1 {port} "
+         f"{dir_path} | head -n 1'")
     tr.Processes.Default.ReturnCode = 0
     # Generate and set the 'gold file' to check stdout
     goldFilePath = os.path.join(data_path, '{0}.gold'.format(tr.Name))
diff --git a/tests/gold_tests/slow_post/slow_post.test.py b/tests/gold_tests/slow_post/slow_post.test.py
index 35bcbec644d..1de7ddbfeab 100644
--- a/tests/gold_tests/slow_post/slow_post.test.py
+++ b/tests/gold_tests/slow_post/slow_post.test.py
@@ -16,6 +16,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
 
 Test.SkipUnless(
     Condition.PluginExists('request_buffer.so')
@@ -60,8 +61,8 @@ def setupTS(self):
 
     def run(self):
         tr = Test.AddTestRun()
-        tr.Processes.Default.Command = 'python3 {0} -p {1} -c {2}'.format(
-            self._slow_post_client, self._ts.Variables.port, self._origin_max_connections)
+        tr.Processes.Default.Command = \
+            f'{sys.executable} {self._slow_post_client} -p {self._ts.Variables.port} -c {self._origin_max_connections}'
         tr.Processes.Default.ReturnCode = 0
         tr.Processes.Default.StartBefore(self._server)
         tr.Processes.Default.StartBefore(Test.Processes.ts)
diff --git a/tests/gold_tests/thread_config/thread_config.test.py b/tests/gold_tests/thread_config/thread_config.test.py
index a1e6324251a..0ef86a1599b 100644
--- a/tests/gold_tests/thread_config/thread_config.test.py
+++ b/tests/gold_tests/thread_config/thread_config.test.py
@@ -16,6 +16,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
 
 Test.Summary = 'Test that Trafficserver starts with different thread configurations.'
 Test.ContinueOnFail = True
@@ -33,7 +34,8 @@
 ts.Setup.CopyAs('check_threads.py', Test.RunDirectory)
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 1, 0, 1, 1)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 1 -a 0 -t 1 -c 1'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -49,7 +51,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 1, 1, 2, 8)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 1 -a 1 -t 2 -c 8'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -65,8 +68,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(
-    ts.Env['TS_ROOT'], 1, 10, 10, 32)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 1 -a 10 -t 10 -c 32'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -82,7 +85,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 2, 0, 1, 1)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 2 -a 0 -t 1 -c 1'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -98,7 +102,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 2, 1, 2, 8)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 2 -a 1 -t 2 -c 8'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -114,8 +119,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(
-    ts.Env['TS_ROOT'], 2, 10, 10, 32)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 2 -a 10 -t 10 -c 32'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -131,7 +136,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 32, 0, 1, 1)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 32 -a 0 -t 1 -c 1'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -147,7 +153,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 32, 1, 2, 8)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 32 -a 1 -t 2 -c 8'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -163,8 +170,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(
-    ts.Env['TS_ROOT'], 32, 10, 10, 32)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 32 -a 10 -t 10 -c 32'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -180,7 +187,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 100, 0, 1, 1)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 100 -a 0 -t 1 -c 1'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -196,7 +204,8 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(ts.Env['TS_ROOT'], 100, 1, 2, 8)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 100 -a 1 -t 2 -c 8'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
 
@@ -212,7 +221,7 @@
     'proxy.config.diags.debug.tags': 'iocore_thread_start|iocore_net_accept_start'})
 
 tr = Test.AddTestRun()
-tr.Processes.Default.Command = 'python3 check_threads.py -p {0} -e {1} -a {2} -t {3} -c {4}'.format(
-    ts.Env['TS_ROOT'], 100, 10, 10, 32)
+TS_ROOT = ts.Env['TS_ROOT']
+tr.Processes.Default.Command = f'{sys.executable} check_threads.py -p {TS_ROOT} -e 100 -a 10 -t 10 -c 32'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.StartBefore(ts)
diff --git a/tests/gold_tests/tls/tls_0rtt_server.test.py b/tests/gold_tests/tls/tls_0rtt_server.test.py
index 2c69ec087f2..a86e9795f4b 100644
--- a/tests/gold_tests/tls/tls_0rtt_server.test.py
+++ b/tests/gold_tests/tls/tls_0rtt_server.test.py
@@ -16,6 +16,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
+import sys
+
 Test.Summary = '''
 Test ATS TLSv1.3 0-RTT support
 '''
@@ -143,8 +145,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/1.1 GET)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h1', 'get', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h1 get {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression('early data accepted', '')
 tr.Processes.Default.Streams.All += Testers.ExcludesExpression('curl test', '')
@@ -152,8 +153,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/1.1 POST)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h1', 'post', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h1 post {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression('HTTP/1.1 425 Too Early', '')
 tr.Processes.Default.Streams.All += Testers.ExcludesExpression('curl test', '')
@@ -162,8 +162,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/2 GET)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h2', 'get', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h2 get {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression('early data accepted', '')
 tr.Processes.Default.Streams.All += Testers.ExcludesExpression('curl test', '')
@@ -171,8 +170,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/2 POST)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h2', 'post', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h2 post {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression(':status 425', 'Only safe methods are allowed')
 tr.Processes.Default.Streams.All += Testers.ExcludesExpression('curl test', '')
@@ -181,8 +179,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/2 Multiplex)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h2', 'multi1', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h2 multi1 {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression('early data accepted multi_1', '')
 tr.Processes.Default.Streams.All += Testers.ContainsExpression('early data accepted multi_2', '')
@@ -192,8 +189,7 @@
 tr.StillRunningAfter += ts
 
 tr = Test.AddTestRun('TLSv1.3 0-RTT Support (HTTP/2 Multiplex with POST)')
-tr.Processes.Default.Command = 'python3 test-0rtt-s_client.py {0} {1} {2} {3}'.format(
-    ts.Variables.ssl_port, 'h2', 'multi2', Test.RunDirectory)
+tr.Processes.Default.Command = f'{sys.executable} test-0rtt-s_client.py {ts.Variables.ssl_port} h2 multi2 {Test.RunDirectory}'
 tr.Processes.Default.ReturnCode = 0
 tr.Processes.Default.Streams.All = Testers.ContainsExpression('early data accepted multi_1', '')
 tr.Processes.Default.Streams.All += Testers.ContainsExpression(':status 425', 'Only safe methods are allowed')