diff --git a/tests/resources/jupyter_server_config.py b/tests/resources/jupyter_server_config.py
index ac1e0dfe..1b715a37 100644
--- a/tests/resources/jupyter_server_config.py
+++ b/tests/resources/jupyter_server_config.py
@@ -13,11 +13,29 @@ def _get_path(*args):
 c = get_config()  # noqa
 
 
+def get_command(port):
+    return [sys.executable, _get_path("httpinfo.py"), f"--port={port}"]
+
+
+def get_command_unix_socket(unix_socket):
+    return [sys.executable, _get_path("httpinfo.py"), f"--unix-socket={unix_socket}"]
+
+
+def get_environment(base_url):
+    return {"JUPYTERLAB_BASE_URL": base_url, "MYVAR": "String with escaped {{var}}"}
+
+
 def mappathf(path):
     p = path + "mapped"
     return p
 
 
+def request_headers_overwrite():
+    return {
+        "X-Custom-Header": "pytest-23456",
+    }
+
+
 def translate_ciao(path, host, response, orig_response, port):
     # Assume that the body has not been modified by any previous rewrite
     assert response.body == orig_response.body
@@ -47,10 +65,6 @@ def cats_only(response, path):
         response.body = b"dogs not allowed"
 
 
-def my_env():
-    return {"MYVAR": "String with escaped {{var}}"}
-
-
 c.ServerProxy.servers = {
     "python-http": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
@@ -63,19 +77,39 @@ def my_env():
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
         "port": 54321,
     },
+    "python-http-callable-command": {
+        "command": get_command,
+    },
     "python-http-mappath": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
         "mappath": {
             "/": "/index.html",
         },
     },
-    "python-http-mappathf": {
+    "python-http-callable-mappath": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
         "mappath": mappathf,
     },
-    "python-http-callable-env": {
+    "python-http-environment": {
+        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
+        "environment": {
+            "JUPYTERLAB_BASE_URL": "{base_url}",
+            "MYVAR": "String with escaped {{var}}",
+        },
+    },
+    "python-http-callable-environment": {
         "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
-        "environment": my_env,
+        "environment": get_environment,
+    },
+    "python-http-request-headers": {
+        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
+        "request_headers_override": {
+            "X-Custom-Header": "pytest-23456",
+        },
+    },
+    "python-http-callable-request-headers": {
+        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
+        "request_headers_override": request_headers_overwrite,
     },
     "python-websocket": {
         "command": [sys.executable, _get_path("websocket.py"), "--port={port}"],
@@ -94,6 +128,10 @@ def my_env():
         ],
         "unix_socket": True,
     },
+    "python-unix-socket-callable": {
+        "command": get_command_unix_socket,
+        "unix_socket": True,
+    },
     "python-unix-socket-file": {
         "command": [
             sys.executable,
@@ -107,12 +145,6 @@ def my_env():
         # python-unix-socket-file
         "unix_socket": "/tmp/jupyter-server-proxy-test-socket",
     },
-    "python-request-headers": {
-        "command": [sys.executable, _get_path("httpinfo.py"), "--port={port}"],
-        "request_headers_override": {
-            "X-Custom-Header": "pytest-23456",
-        },
-    },
     "python-gzipserver": {
         "command": [sys.executable, _get_path("gzipserver.py"), "{port}"],
     },
diff --git a/tests/test_proxies.py b/tests/test_proxies.py
index 4573517c..1016481f 100644
--- a/tests/test_proxies.py
+++ b/tests/test_proxies.py
@@ -33,6 +33,12 @@ def request_get(port, path, token, host=LOCALHOST):
             sys.platform == "win32", reason="Unix socket not supported on Windows"
         ),
     ),
+    pytest.param(
+        "/python-unix-socket-callable/",
+        marks=pytest.mark.skipif(
+            sys.platform == "win32", reason="Unix socket not supported on Windows"
+        ),
+    ),
     pytest.param(
         "/python-unix-socket-file/",
         marks=pytest.mark.skipif(
@@ -279,6 +285,18 @@ def test_server_proxy_port_non_service_rewrite_response(
     assert s.startswith("GET /foo?token=")
 
 
+def test_server_proxy_command_callable(
+    a_server_port_and_token: Tuple[int, str]
+) -> None:
+    PORT, TOKEN = a_server_port_and_token
+    r = request_get(PORT, "/python-http-callable-command/abc", TOKEN)
+    assert r.code == 200
+    s = r.read().decode("ascii")
+    assert s.startswith("GET /abc?token=")
+    assert "X-Forwarded-Context: /python-http-callable-command\n" in s
+    assert "X-Proxycontextpath: /python-http-callable-command\n" in s
+
+
 @pytest.mark.parametrize(
     "requestpath,expected",
     [
@@ -311,28 +329,48 @@ def test_server_proxy_mappath_callable(
     requestpath, expected, a_server_port_and_token: Tuple[int, str]
 ) -> None:
     PORT, TOKEN = a_server_port_and_token
-    r = request_get(PORT, "/python-http-mappathf" + requestpath, TOKEN)
+    r = request_get(PORT, "/python-http-callable-mappath" + requestpath, TOKEN)
     assert r.code == 200
     s = r.read().decode("ascii")
     assert s.startswith("GET " + expected)
-    assert "X-Forwarded-Context: /python-http-mappathf\n" in s
-    assert "X-Proxycontextpath: /python-http-mappathf\n" in s
+    assert "X-Forwarded-Context: /python-http-callable-mappath\n" in s
+    assert "X-Proxycontextpath: /python-http-callable-mappath\n" in s
 
 
-def test_server_proxy_remote(a_server_port_and_token: Tuple[int, str]) -> None:
+@pytest.mark.parametrize(
+    "name", ["python-http-environment", "python-http-callable-environment"]
+)
+def test_server_proxy_environment(
+    name: str, a_server_port_and_token: Tuple[int, str]
+) -> None:
     PORT, TOKEN = a_server_port_and_token
-    r = request_get(PORT, "/newproxy", TOKEN, host="127.0.0.1")
+    r = request_get(PORT, f"/{name}/test", TOKEN)
     assert r.code == 200
+    s = r.read().decode("ascii")
+    assert s.startswith("GET /test?token=")
+    assert f"X-Forwarded-Context: /{name}\n" in s
+    assert f"X-Proxycontextpath: /{name}\n" in s
 
 
-def test_server_request_headers(a_server_port_and_token: Tuple[int, str]) -> None:
+@pytest.mark.parametrize(
+    "name", ["python-http-request-headers", "python-http-callable-request-headers"]
+)
+def test_server_proxy_request_headers(
+    name, a_server_port_and_token: Tuple[int, str]
+) -> None:
     PORT, TOKEN = a_server_port_and_token
-    r = request_get(PORT, "/python-request-headers/", TOKEN, host="127.0.0.1")
+    r = request_get(PORT, f"/{name}/", TOKEN, host="127.0.0.1")
     assert r.code == 200
     s = r.read().decode("ascii")
     assert "X-Custom-Header: pytest-23456\n" in s
 
 
+def test_server_proxy_remote(a_server_port_and_token: Tuple[int, str]) -> None:
+    PORT, TOKEN = a_server_port_and_token
+    r = request_get(PORT, "/newproxy", TOKEN, host="127.0.0.1")
+    assert r.code == 200
+
+
 def test_server_content_encoding_header(
     a_server_port_and_token: Tuple[int, str]
 ) -> None:
@@ -498,14 +536,6 @@ def test_bad_server_proxy_url(
         assert "X-ProxyContextPath" not in r.headers
 
 
-def test_callable_environment_formatting(
-    a_server_port_and_token: Tuple[int, str]
-) -> None:
-    PORT, TOKEN = a_server_port_and_token
-    r = request_get(PORT, "/python-http-callable-env/test", TOKEN)
-    assert r.code == 200
-
-
 @pytest.mark.parametrize(
     "rawsocket_type",
     [