diff --git a/tests/http/test_02_download.py b/tests/http/test_02_download.py
index 69b31183d5..c75f932b72 100644
--- a/tests/http/test_02_download.py
+++ b/tests/http/test_02_download.py
@@ -473,8 +473,10 @@ class TestDownload:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
diff --git a/tests/http/test_07_upload.py b/tests/http/test_07_upload.py
index fee50387c5..6cb4d943e1 100644
--- a/tests/http/test_07_upload.py
+++ b/tests/http/test_07_upload.py
@@ -57,7 +57,8 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-0]'
         r = curl.http_upload(urls=[url], data=data, alpn_proto=proto)
         r.check_stats(count=1, http_status=200, exitcode=0)
-        respdata = open(curl.response_file(0)).readlines()
+        with open(curl.response_file(0)) as fr:
+            respdata = fr.readlines()
         assert respdata == [data]
 
     # upload large data, check that this is what was echoed
@@ -68,8 +69,9 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-0]'
         r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto)
         r.check_stats(count=1, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
-        respdata = open(curl.response_file(0)).readlines()
+        with open(fdata) as fi, open(curl.response_file(0)) as fr:
+            indata = fi.readlines()
+            respdata = fr.readlines()
         assert respdata == indata
 
     # upload data sequentially, check that they were echoed
@@ -82,7 +84,8 @@ class TestUpload:
         r = curl.http_upload(urls=[url], data=data, alpn_proto=proto)
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == [data]
 
     # upload data parallel, check that they were echoed
@@ -97,7 +100,8 @@ class TestUpload:
                              extra_args=['--parallel'])
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == [data]
 
     # upload large data sequentially, check that this is what was echoed
@@ -109,10 +113,12 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-{count-1}]'
         r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto)
         r.check_response(count=count, http_status=200)
-        indata = open(fdata).readlines()
+        with open(fdata) as fi:
+            indata = fi.readlines()
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == indata
 
     # upload very large data sequentially, check that this is what was echoed
@@ -124,9 +130,11 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-{count-1}]'
         r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto)
         r.check_stats(count=count, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
+        with open(fdata) as fi:
+            indata = fi.readlines()
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == indata
 
     # upload from stdin, issue #14870
@@ -141,7 +149,8 @@ class TestUpload:
         r = curl.http_put(urls=[url], data=indata, alpn_proto=proto)
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == [f'{len(indata)}']
 
     @pytest.mark.parametrize("proto", Env.http_protos())
@@ -198,7 +207,8 @@ class TestUpload:
                              extra_args=['--parallel'])
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == [data]
 
     # upload large data parallel, check that this is what was echoed
@@ -243,7 +253,8 @@ class TestUpload:
         exp_data = [f'{os.path.getsize(fdata)}']
         r.check_response(count=count, http_status=200)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == exp_data
 
     # PUT 10m
@@ -259,7 +270,8 @@ class TestUpload:
         exp_data = [f'{os.path.getsize(fdata)}']
         r.check_response(count=count, http_status=200)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == exp_data
 
     # issue #10591
@@ -351,8 +363,9 @@ class TestUpload:
         r.check_response(count=1, http_status=200)
         # apache does not Upgrade on request with a body
         assert r.stats[0]['http_version'] == '1.1', f'{r}'
-        indata = open(fdata).readlines()
-        respdata = open(curl.response_file(0)).readlines()
+        with open(fdata) as fi, open(curl.response_file(0)) as fr:
+            indata = fi.readlines()
+            respdata = fr.readlines()
         assert respdata == indata
 
     # upload to a 301,302,303 response
@@ -368,7 +381,8 @@ class TestUpload:
             '-L', '--trace-config', 'http/2,http/3'
         ])
         r.check_response(count=1, http_status=200)
-        respdata = open(curl.response_file(0)).readlines()
+        with open(curl.response_file(0)) as fr:
+            respdata = fr.readlines()
         assert respdata == []  # was transformed to a GET
 
     # upload to a 307 response
@@ -383,7 +397,8 @@ class TestUpload:
             '-L', '--trace-config', 'http/2,http/3'
         ])
         r.check_response(count=1, http_status=200)
-        respdata = open(curl.response_file(0)).readlines()
+        with open(curl.response_file(0)) as fr:
+            respdata = fr.readlines()
         assert respdata == [data]  # was POST again
 
     # POST form data, yet another code path in transfer
@@ -406,8 +421,9 @@ class TestUpload:
             '--trace-config', 'http/2,http/3'
         ])
         r.check_stats(count=1, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
-        respdata = open(curl.response_file(0)).readlines()
+        with open(fdata) as fi, open(curl.response_file(0)) as fr:
+            indata = fi.readlines()
+            respdata = fr.readlines()
         assert respdata == indata
 
     # POST data urlencoded, large enough to be sent separate from request headers
@@ -420,8 +436,9 @@ class TestUpload:
             '--trace-config', 'http/2,http/3'
         ])
         r.check_stats(count=1, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
-        respdata = open(curl.response_file(0)).readlines()
+        with open(fdata) as fi, open(curl.response_file(0)) as fr:
+            indata = fi.readlines()
+            respdata = fr.readlines()
         assert respdata == indata
 
     # POST data urlencoded, small enough to be sent with request headers
@@ -442,8 +459,9 @@ class TestUpload:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-0]'
         r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto, extra_args=extra_args)
         r.check_stats(count=1, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
-        respdata = open(curl.response_file(0)).readlines()
+        with open(fdata) as fi, open(curl.response_file(0)) as fr:
+            indata = fi.readlines()
+            respdata = fr.readlines()
         assert respdata == indata
 
     def check_download(self, r: ExecResult, count: int, srcfile: Union[str, os.PathLike], curl: CurlClient):
@@ -451,8 +469,10 @@ class TestUpload:
             dfile = curl.download_file(i)
             assert os.path.exists(dfile), f'download {dfile} missing\n{r.dump_logs()}'
             if not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -699,8 +719,9 @@ class TestUpload:
             dfile = client.download_file(i)
             assert os.path.exists(dfile), f'download {dfile} missing\n{r.dump_logs()}'
             if complete:
-                diff = "".join(difflib.unified_diff(a=source,
-                                                    b=open(dfile).readlines(),
+                with open(dfile) as fb:
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=source, b=b,
                                                     fromfile='-',
                                                     tofile=dfile,
                                                     n=1))
diff --git a/tests/http/test_08_caddy.py b/tests/http/test_08_caddy.py
index efee4bc48b..23cea4582a 100644
--- a/tests/http/test_08_caddy.py
+++ b/tests/http/test_08_caddy.py
@@ -151,7 +151,8 @@ class TestCaddy:
                              extra_args=['--parallel'])
         r.check_stats(count=count, http_status=200, exitcode=0)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == [data]
 
     # put large file, check that they length were echoed
@@ -166,7 +167,8 @@ class TestCaddy:
         exp_data = [f'{os.path.getsize(fdata)}']
         r.check_response(count=count, http_status=200)
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == exp_data
 
     @pytest.mark.parametrize("proto", Env.http_protos())
@@ -210,8 +212,10 @@ class TestCaddy:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
diff --git a/tests/http/test_10_proxy.py b/tests/http/test_10_proxy.py
index f81260a28f..94a13ef490 100644
--- a/tests/http/test_10_proxy.py
+++ b/tests/http/test_10_proxy.py
@@ -57,7 +57,6 @@ class TestProxy:
             if m:
                 return m.group(1)
         assert False, f'tunnel protocol not found in:\n{"".join(r.trace_lines)}'
-        return None
 
     # download via http: proxy (no tunnel)
     def test_10_01_proxy_http(self, env: Env, httpd):
@@ -105,9 +104,11 @@ class TestProxy:
                              extra_args=xargs)
         r.check_response(count=count, http_status=200,
                          protocol='HTTP/2' if proto == 'h2' else 'HTTP/1.1')
-        indata = open(srcfile).readlines()
+        with open(srcfile) as fi:
+            indata = fi.readlines()
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == indata
 
     # download http: via http: proxytunnel
@@ -229,9 +230,11 @@ class TestProxy:
         assert self.get_tunnel_proto_used(r) == tunnel
         r.check_response(count=count, http_status=200)
         assert r.total_connects == 1, r.dump_logs()
-        indata = open(srcfile).readlines()
+        with open(srcfile) as fi:
+            indata = fi.readlines()
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == indata, f'response {i} differs'
 
     @pytest.mark.skipif(condition=not Env.have_ssl_curl(), reason="curl without SSL")
diff --git a/tests/http/test_13_proxy_auth.py b/tests/http/test_13_proxy_auth.py
index d74a9f280b..50e4596057 100644
--- a/tests/http/test_13_proxy_auth.py
+++ b/tests/http/test_13_proxy_auth.py
@@ -48,7 +48,6 @@ class TestProxyAuth:
             if m:
                 return m.group(1)
         assert False, f'tunnel protocol not found in:\n{"".join(r.trace_lines)}'
-        return None
 
     # download via http: proxy (no tunnel), no auth
     def test_13_01_proxy_no_auth(self, env: Env, httpd, configures_httpd):
diff --git a/tests/http/test_17_ssl_use.py b/tests/http/test_17_ssl_use.py
index 0f3b2ccb62..4179925f42 100644
--- a/tests/http/test_17_ssl_use.py
+++ b/tests/http/test_17_ssl_use.py
@@ -243,10 +243,10 @@ class TestSSLUse:
                                succeed13, succeed12):
         # to test setting cipher suites, the AES 256 ciphers are disabled in the test server
         httpd.set_extra_config('base', [
-            'SSLCipherSuite SSL'
-            ' ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256'
+            'SSLCipherSuite SSL' +
+            ' ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256' +
             ':ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305',
-            'SSLCipherSuite TLSv1.3'
+            'SSLCipherSuite TLSv1.3' +
             ' TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256',
             f'SSLProtocol {tls_proto}'
         ])
@@ -525,10 +525,10 @@ class TestSSLUse:
     def test_17_18_gnutls_priority(self, env: Env, httpd, configures_httpd, priority, tls_proto, ciphers, success):
         # to test setting cipher suites, the AES 256 ciphers are disabled in the test server
         httpd.set_extra_config('base', [
-            'SSLCipherSuite SSL'
-            ' ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256'
+            'SSLCipherSuite SSL' +
+            ' ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256' +
             ':ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305',
-            'SSLCipherSuite TLSv1.3'
+            'SSLCipherSuite TLSv1.3' +
             ' TLS_AES_128_GCM_SHA256:TLS_CHACHA20_POLY1305_SHA256',
         ])
         httpd.reload_if_config_changed()
diff --git a/tests/http/test_30_vsftpd.py b/tests/http/test_30_vsftpd.py
index a57882f520..d625852249 100644
--- a/tests/http/test_30_vsftpd.py
+++ b/tests/http/test_30_vsftpd.py
@@ -77,7 +77,8 @@ class TestVsFTPD:
         url = f'ftp://{env.ftp_domain}:{vsftpd.port}/'
         r = curl.ftp_get(urls=[url], with_stats=True)
         r.check_stats(count=1, http_status=226)
-        lines = open(os.path.join(curl.run_dir, 'download_#1.data')).readlines()
+        with open(os.path.join(curl.run_dir, 'download_#1.data')) as fd:
+            lines = fd.readlines()
         assert len(lines) == 5, f'list: {lines}'
         r.check_stats_timelines()
 
@@ -251,8 +252,10 @@ class TestVsFTPD:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -264,8 +267,10 @@ class TestVsFTPD:
         assert os.path.exists(srcfile)
         assert os.path.exists(dstfile)
         if not filecmp.cmp(srcfile, dstfile, shallow=False):
-            diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                b=open(dstfile).readlines(),
+            with open(srcfile) as fa, open(dstfile) as fb:
+                a = fa.readlines()
+                b = fb.readlines()
+            diff = "".join(difflib.unified_diff(a=a, b=b,
                                                 fromfile=srcfile,
                                                 tofile=dstfile,
                                                 n=1))
diff --git a/tests/http/test_31_vsftpds.py b/tests/http/test_31_vsftpds.py
index 5858d9e461..ac4c154c47 100644
--- a/tests/http/test_31_vsftpds.py
+++ b/tests/http/test_31_vsftpds.py
@@ -82,7 +82,8 @@ class TestVsFTPD:
         url = f'ftp://{env.ftp_domain}:{vsftpds.port}/'
         r = curl.ftp_ssl_get(urls=[url], with_stats=True)
         r.check_stats(count=1, http_status=226)
-        lines = open(os.path.join(curl.run_dir, 'download_#1.data')).readlines()
+        with open(os.path.join(curl.run_dir, 'download_#1.data')) as fd:
+            lines = fd.readlines()
         assert len(lines) == 4, f'list: {lines}'
         r.check_stats_timelines()
 
@@ -203,7 +204,8 @@ class TestVsFTPD:
         r.check_stats(count=count, http_status=226)
         # expect the uploaded file to be number of converted newlines larger
         dstsize = os.path.getsize(dstfile)
-        newlines = len(open(srcfile).readlines())
+        with open(srcfile) as fd:
+            newlines = len(fd.readlines())
         assert (srcsize + newlines) == dstsize, \
             f'expected source with {newlines} lines to be that much larger,'\
             f'instead srcsize={srcsize}, upload size={dstsize}, diff={dstsize-srcsize}'
@@ -248,7 +250,8 @@ class TestVsFTPD:
         r = curl.ftp_ssl_upload(urls=[url], updata=indata, with_stats=True)
         r.check_stats(count=count, http_status=226)
         assert os.path.exists(dstfile)
-        destdata = open(dstfile).readlines()
+        with open(dstfile) as fd:
+            destdata = fd.readlines()
         expdata = [indata] if len(indata) else []
         assert expdata == destdata, f'expected: {expdata}, got: {destdata}'
 
@@ -300,8 +303,10 @@ class TestVsFTPD:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -313,8 +318,10 @@ class TestVsFTPD:
         assert os.path.exists(srcfile)
         assert os.path.exists(dstfile)
         if not filecmp.cmp(srcfile, dstfile, shallow=False):
-            diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                b=open(dstfile).readlines(),
+            with open(srcfile) as fa, open(dstfile) as fb:
+                a = fa.readlines()
+                b = fb.readlines()
+            diff = "".join(difflib.unified_diff(a=a, b=b,
                                                 fromfile=srcfile,
                                                 tofile=dstfile,
                                                 n=1))
diff --git a/tests/http/test_32_ftps_vsftpd.py b/tests/http/test_32_ftps_vsftpd.py
index b167664661..1181bb3211 100644
--- a/tests/http/test_32_ftps_vsftpd.py
+++ b/tests/http/test_32_ftps_vsftpd.py
@@ -82,7 +82,8 @@ class TestFtpsVsFTPD:
         url = f'ftps://{env.ftp_domain}:{vsftpds.port}/'
         r = curl.ftp_get(urls=[url], with_stats=True)
         r.check_stats(count=1, http_status=226)
-        lines = open(os.path.join(curl.run_dir, 'download_#1.data')).readlines()
+        with open(os.path.join(curl.run_dir, 'download_#1.data')) as fd:
+            lines = fd.readlines()
         assert len(lines) == 4, f'list: {lines}'
         r.check_stats_timelines()
 
@@ -216,7 +217,8 @@ class TestFtpsVsFTPD:
         r.check_stats(count=count, http_status=226)
         # expect the uploaded file to be number of converted newlines larger
         dstsize = os.path.getsize(dstfile)
-        newlines = len(open(srcfile).readlines())
+        with open(srcfile) as fd:
+            newlines = len(fd.readlines())
         assert (srcsize + newlines) == dstsize, \
             f'expected source with {newlines} lines to be that much larger,'\
             f'instead srcsize={srcsize}, upload size={dstsize}, diff={dstsize-srcsize}'
@@ -261,7 +263,8 @@ class TestFtpsVsFTPD:
         r = curl.ftp_upload(urls=[url], updata=indata, with_stats=True)
         r.check_stats(count=count, http_status=226)
         assert os.path.exists(dstfile)
-        destdata = open(dstfile).readlines()
+        with open(dstfile) as fd:
+            destdata = fd.readlines()
         expdata = [indata] if len(indata) else []
         assert expdata == destdata, f'expected: {expdata}, got: {destdata}'
 
@@ -289,8 +292,10 @@ class TestFtpsVsFTPD:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -302,8 +307,10 @@ class TestFtpsVsFTPD:
         assert os.path.exists(srcfile)
         assert os.path.exists(dstfile)
         if not filecmp.cmp(srcfile, dstfile, shallow=False):
-            diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                b=open(dstfile).readlines(),
+            with open(srcfile) as fa, open(dstfile) as fb:
+                a = fa.readlines()
+                b = fb.readlines()
+            diff = "".join(difflib.unified_diff(a=a, b=b,
                                                 fromfile=srcfile,
                                                 tofile=dstfile,
                                                 n=1))
diff --git a/tests/http/test_40_socks.py b/tests/http/test_40_socks.py
index 9702aa1110..471f1948fb 100644
--- a/tests/http/test_40_socks.py
+++ b/tests/http/test_40_socks.py
@@ -96,7 +96,9 @@ class TestSocks:
         url = f'https://{env.authority_for(env.domain1, proto)}/curltest/echo?id=[0-{count-1}]'
         r = curl.http_upload(urls=[url], data=f'@{fdata}', alpn_proto=proto)
         r.check_stats(count=count, http_status=200, exitcode=0)
-        indata = open(fdata).readlines()
+        with open(fdata) as fi:
+            indata = fi.readlines()
         for i in range(count):
-            respdata = open(curl.response_file(i)).readlines()
+            with open(curl.response_file(i)) as fr:
+                respdata = fr.readlines()
             assert respdata == indata
diff --git a/tests/http/test_50_scp.py b/tests/http/test_50_scp.py
index 5bfba23f33..831ee5b3f8 100644
--- a/tests/http/test_50_scp.py
+++ b/tests/http/test_50_scp.py
@@ -191,8 +191,10 @@ class TestScp:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -202,8 +204,10 @@ class TestScp:
         assert os.path.exists(srcfile)
         assert os.path.exists(destfile)
         if not filecmp.cmp(srcfile, destfile, shallow=False):
-            diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                b=open(destfile).readlines(),
+            with open(srcfile) as fa, open(destfile) as fb:
+                a = fa.readlines()
+                b = fb.readlines()
+            diff = "".join(difflib.unified_diff(a=a, b=b,
                                                 fromfile=srcfile,
                                                 tofile=destfile,
                                                 n=1))
diff --git a/tests/http/test_51_sftp.py b/tests/http/test_51_sftp.py
index 76e8727b99..acf76ef683 100644
--- a/tests/http/test_51_sftp.py
+++ b/tests/http/test_51_sftp.py
@@ -191,8 +191,10 @@ class TestSftp:
             dfile = client.download_file(i)
             assert os.path.exists(dfile)
             if complete and not filecmp.cmp(srcfile, dfile, shallow=False):
-                diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                    b=open(dfile).readlines(),
+                with open(srcfile) as fa, open(dfile) as fb:
+                    a = fa.readlines()
+                    b = fb.readlines()
+                diff = "".join(difflib.unified_diff(a=a, b=b,
                                                     fromfile=srcfile,
                                                     tofile=dfile,
                                                     n=1))
@@ -202,8 +204,10 @@ class TestSftp:
         assert os.path.exists(srcfile)
         assert os.path.exists(destfile)
         if not filecmp.cmp(srcfile, destfile, shallow=False):
-            diff = "".join(difflib.unified_diff(a=open(srcfile).readlines(),
-                                                b=open(destfile).readlines(),
+            with open(srcfile) as fa, open(destfile) as fb:
+                a = fa.readlines()
+                b = fb.readlines()
+            diff = "".join(difflib.unified_diff(a=a, b=b,
                                                 fromfile=srcfile,
                                                 tofile=destfile,
                                                 n=1))
diff --git a/tests/http/testenv/client.py b/tests/http/testenv/client.py
index 36ac8a599e..1b4e303ac6 100644
--- a/tests/http/testenv/client.py
+++ b/tests/http/testenv/client.py
@@ -104,8 +104,9 @@ class LocalClient:
             log.warning(f'Timeout after {self._timeout}s: {args}')
             exitcode = -1
             exception = 'TimeoutExpired'
-        coutput = open(self._stdoutfile).readlines()
-        cerrput = open(self._stderrfile).readlines()
+        with open(self._stdoutfile) as fout, open(self._stderrfile) as ferr:
+            coutput = fout.readlines()
+            cerrput = ferr.readlines()
         return ExecResult(args=myargs, exit_code=exitcode, exception=exception,
                           stdout=coutput, stderr=cerrput,
                           duration=datetime.now() - start)
@@ -113,8 +114,10 @@ class LocalClient:
     def dump_logs(self):
         lines = []
         lines.append('>>--stdout ----------------------------------------------\n')
-        lines.extend(open(self._stdoutfile).readlines())
+        with open(self._stdoutfile) as cstdout:
+            lines.extend(cstdout.readlines())
         lines.append('>>--stderr ----------------------------------------------\n')
-        lines.extend(open(self._stderrfile).readlines())
+        with open(self._stderrfile) as cstderr:
+            lines.extend(cstderr.readlines())
         lines.append('<<-------------------------------------------------------\n')
         return ''.join(lines)
diff --git a/tests/http/testenv/curl.py b/tests/http/testenv/curl.py
index 64c1cacd46..0864e2899e 100644
--- a/tests/http/testenv/curl.py
+++ b/tests/http/testenv/curl.py
@@ -393,7 +393,7 @@ class ExecResult:
                                         f'got {self.exit_code}\n{self.dump_logs()}'
         elif code is False:
             assert self.exit_code != 0, f'expected exit code {code}, '\
-                                                f'got {self.exit_code}\n{self.dump_logs()}'
+                                        f'got {self.exit_code}\n{self.dump_logs()}'
         else:
             assert self.exit_code == code, f'expected exit code {code}, '\
                                            f'got {self.exit_code}\n{self.dump_logs()}'
@@ -1072,8 +1072,9 @@ class CurlClient:
             dtrace.finish()
         if self._with_flame:
             self._generate_flame(args, dtrace=dtrace, perf=perf)
-        coutput = open(self._stdoutfile).readlines()
-        cerrput = open(self._stderrfile).readlines()
+        with open(self._stdoutfile) as fout, open(self._stderrfile) as ferr:
+            coutput = fout.readlines()
+            cerrput = ferr.readlines()
         return ExecResult(args=args, exit_code=exitcode, exception=exception,
                           stdout=coutput, stderr=cerrput,
                           duration=ended_at - started_at,
@@ -1167,7 +1168,8 @@ class CurlClient:
         return args
 
     def _parse_headerfile(self, headerfile: str, r: Optional[ExecResult] = None) -> ExecResult:
-        lines = open(headerfile).readlines()
+        with open(headerfile) as fd:
+            lines = fd.readlines()
         if r is None:
             r = ExecResult(args=[], exit_code=0, stdout=[], stderr=[])
 
diff --git a/tests/http/testenv/sshd.py b/tests/http/testenv/sshd.py
index e800ced17b..83accd7492 100644
--- a/tests/http/testenv/sshd.py
+++ b/tests/http/testenv/sshd.py
@@ -132,7 +132,8 @@ class Sshd:
                 self._host_key_files.append(key_file)
                 pub_file = f'{key_file}.pub'
                 self._host_pub_files.append(pub_file)
-                pubkey = open(pub_file).read()
+                with open(pub_file) as fp:
+                    pubkey = fp.read()
                 # fd_known.write(f'[127.0.0.1]:{self.port} {pubkey}')
                 fd_known.write(f'[{self.env.domain1.lower()}]:{self.port} {pubkey}')
                 fd_unknown.write(f'dummy.invalid {pubkey}')
@@ -159,7 +160,8 @@ class Sshd:
             self._user_pub_files.append(f'{key_file}.pub')
         with open(self._auth_keys, 'w') as fd:
             os.chmod(self._auth_keys, stat.S_IRUSR | stat.S_IWUSR)
-            pubkey = open(self._user_pub_files[0]).read()
+            with open(self._user_pub_files[0]) as fp:
+                pubkey = fp.read()
             fd.write(pubkey)
 
     def clear_logs(self):