diff --git a/irctest/controllers/inspircd.py b/irctest/controllers/inspircd.py
index b932ec2..106d8fd 100644
--- a/irctest/controllers/inspircd.py
+++ b/irctest/controllers/inspircd.py
@@ -73,6 +73,7 @@ TEMPLATE_CONFIG = """
 <module name="m_muteban">  # for testing mute extbans
 <module name="namesx"> # For multi-prefix
 <module name="sasl">
+<module name="uhnames">  # For userhost-in-names
 
 # HELP/HELPOP
 <module name="alias">  # for the HELP alias
diff --git a/irctest/server_tests/cap.py b/irctest/server_tests/cap.py
index 95c4027..b6b0d5e 100644
--- a/irctest/server_tests/cap.py
+++ b/irctest/server_tests/cap.py
@@ -4,11 +4,32 @@
 """
 
 from irctest import cases
-from irctest.patma import ANYSTR
+from irctest.patma import ANYSTR, StrRe
 from irctest.runner import CapabilityNotSupported, ImplementationChoice
 
 
 class CapTestCase(cases.BaseServerTestCase):
+    @cases.mark_specifications("IRCv3")
+    def testInvalidCapSubcommand(self):
+        """“If no capabilities are active, an empty parameter must be sent.”
+        -- <http://ircv3.net/specs/core/capability-negotiation-3.1.html#the-cap-list-subcommand>
+        """  # noqa
+        self.addClient()
+        self.sendLine(1, "CAP NOTACOMMAND")
+        self.sendLine(1, "PING test123")
+        m = self.getRegistrationMessage(1)
+        self.assertTrue(
+            self.messageDiffers(m, command="PONG", params=[ANYSTR, "test123"]),
+            "Sending “CAP NOTACOMMAND” as first message got no reply",
+        )
+        self.assertMessageMatch(
+            m,
+            command="410",
+            params=["*", "NOTACOMMAND", ANYSTR],
+            fail_msg="Sending “CAP NOTACOMMAND” as first message got a reply "
+            "that is not ERR_INVALIDCAPCMD: {msg}",
+        )
+
     @cases.mark_specifications("IRCv3")
     def testNoReq(self):
         """Test the server handles gracefully clients which do not send
@@ -23,12 +44,206 @@ class CapTestCase(cases.BaseServerTestCase):
         self.getCapLs(1)
         self.sendLine(1, "USER foo foo foo :foo")
         self.sendLine(1, "NICK foo")
+
+        # Make sure the server didn't send anything yet
+        self.sendLine(1, "CAP LS 302")
+        self.getCapLs(1)
+
         self.sendLine(1, "CAP END")
         m = self.getRegistrationMessage(1)
         self.assertMessageMatch(
             m, command="001", fail_msg="Expected 001 after sending CAP END, got {msg}."
         )
 
+    @cases.mark_specifications("IRCv3")
+    def testReqOne(self):
+        """Tests requesting a single capability"""
+        self.addClient(1)
+        self.sendLine(1, "CAP LS")
+        self.getCapLs(1)
+        self.sendLine(1, "USER foo foo foo :foo")
+        self.sendLine(1, "NICK foo")
+        self.sendLine(1, "CAP REQ :multi-prefix")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("multi-prefix ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP LIST")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "LIST", StrRe("multi-prefix ?")],
+            fail_msg="Expected CAP LIST after sending CAP LIST, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP END")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m, command="001", fail_msg="Expected 001 after sending CAP END, got {msg}."
+        )
+
+    @cases.mark_specifications("IRCv3")
+    @cases.xfailIfSoftware(
+        ["ngIRCd"],
+        "ngIRCd does not support userhost-in-names",
+    )
+    def testReqTwo(self):
+        """Tests requesting two capabilities at once"""
+        self.addClient(1)
+        self.sendLine(1, "CAP LS")
+        self.getCapLs(1)
+        self.sendLine(1, "USER foo foo foo :foo")
+        self.sendLine(1, "NICK foo")
+        self.sendLine(1, "CAP REQ :multi-prefix userhost-in-names")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("multi-prefix userhost-in-names ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP LIST")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[
+                ANYSTR,
+                "LIST",
+                StrRe(
+                    "(multi-prefix userhost-in-names|userhost-in-names multi-prefix) ?"
+                ),
+            ],
+            fail_msg="Expected CAP LIST after sending CAP LIST, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP END")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m, command="001", fail_msg="Expected 001 after sending CAP END, got {msg}."
+        )
+
+    @cases.mark_specifications("IRCv3")
+    @cases.xfailIfSoftware(
+        ["ngIRCd"],
+        "ngIRCd does not support userhost-in-names",
+    )
+    def testReqOneThenOne(self):
+        """Tests requesting two capabilities in different messages"""
+        self.addClient(1)
+        self.sendLine(1, "CAP LS")
+        self.getCapLs(1)
+        self.sendLine(1, "USER foo foo foo :foo")
+        self.sendLine(1, "NICK foo")
+
+        self.sendLine(1, "CAP REQ :multi-prefix")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("multi-prefix ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP REQ :userhost-in-names")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("userhost-in-names ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP LIST")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[
+                ANYSTR,
+                "LIST",
+                StrRe(
+                    "(multi-prefix userhost-in-names|userhost-in-names multi-prefix) ?"
+                ),
+            ],
+            fail_msg="Expected CAP LIST after sending CAP LIST, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP END")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m, command="001", fail_msg="Expected 001 after sending CAP END, got {msg}."
+        )
+
+    @cases.mark_specifications("IRCv3")
+    @cases.xfailIfSoftware(
+        ["ngIRCd"],
+        "ngIRCd does not support userhost-in-names",
+    )
+    def testReqPostRegistration(self):
+        """Tests requesting more capabilities after CAP END"""
+        self.addClient(1)
+        self.sendLine(1, "CAP LS")
+        self.getCapLs(1)
+        self.sendLine(1, "USER foo foo foo :foo")
+        self.sendLine(1, "NICK foo")
+
+        self.sendLine(1, "CAP REQ :multi-prefix")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("multi-prefix ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP LIST")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "LIST", StrRe("multi-prefix ?")],
+            fail_msg="Expected CAP LIST after sending CAP LIST, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP END")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m, command="001", fail_msg="Expected 001 after sending CAP END, got {msg}."
+        )
+
+        self.getMessages(1)
+
+        self.sendLine(1, "CAP REQ :userhost-in-names")
+        m = self.getRegistrationMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[ANYSTR, "ACK", StrRe("userhost-in-names ?")],
+            fail_msg="Expected CAP ACK after sending CAP REQ, got {msg}.",
+        )
+
+        self.sendLine(1, "CAP LIST")
+        m = self.getMessage(1)
+        self.assertMessageMatch(
+            m,
+            command="CAP",
+            params=[
+                ANYSTR,
+                "LIST",
+                StrRe(
+                    "(multi-prefix userhost-in-names|userhost-in-names multi-prefix) ?"
+                ),
+            ],
+            fail_msg="Expected CAP LIST after sending CAP LIST, got {msg}.",
+        )
+
     @cases.mark_specifications("IRCv3")
     def testReqUnavailable(self):
         """Test the server handles gracefully clients which request
@@ -45,7 +260,7 @@ class CapTestCase(cases.BaseServerTestCase):
         self.assertMessageMatch(
             m,
             command="CAP",
-            params=[ANYSTR, "NAK", "foo"],
+            params=[ANYSTR, "NAK", StrRe("foo ?")],
             fail_msg="Expected CAP NAK after requesting non-existing "
             "capability, got {msg}.",
         )
@@ -78,10 +293,6 @@ class CapTestCase(cases.BaseServerTestCase):
         )
 
     @cases.mark_specifications("IRCv3")
-    @cases.xfailIfSoftware(
-        ["UnrealIRCd"],
-        "UnrealIRCd sends a trailing space on CAP NAK: https://github.com/unrealircd/unrealircd/pull/148",
-    )
     def testNakWhole(self):
         """“The capability identifier set must be accepted as a whole, or
         rejected entirely.”
@@ -123,16 +334,12 @@ class CapTestCase(cases.BaseServerTestCase):
         self.assertMessageMatch(
             m,
             command="CAP",
-            params=[ANYSTR, "ACK", "multi-prefix"],
+            params=[ANYSTR, "ACK", StrRe("multi-prefix ?")],
             fail_msg="Expected “CAP ACK :multi-prefix” after "
             "sending “CAP REQ :multi-prefix”, but got {msg}.",
         )
 
     @cases.mark_specifications("IRCv3")
-    @cases.xfailIfSoftware(
-        ["UnrealIRCd"],
-        "UnrealIRCd sends a trailing space on CAP NAK: https://github.com/unrealircd/unrealircd/pull/148",
-    )
     def testCapRemovalByClient(self):
         """Test CAP LIST and removal of caps via CAP REQ :-tagname."""
         cap1 = "echo-message"
@@ -167,17 +374,19 @@ class CapTestCase(cases.BaseServerTestCase):
         m = self.getMessage(1)
         self.assertIn("time", m.tags, m)
 
-        # remove the server-time cap
+        # remove the multi-prefix cap
         self.sendLine(1, f"CAP REQ :-{cap2}")
         m = self.getMessage(1)
         # Must be either ACK or NAK
-        if self.messageDiffers(m, command="CAP", params=[ANYSTR, "ACK", f"-{cap2}"]):
+        if self.messageDiffers(
+            m, command="CAP", params=[ANYSTR, "ACK", StrRe(f"-{cap2} ?")]
+        ):
             self.assertMessageMatch(
-                m, command="CAP", params=[ANYSTR, "NAK", f"-{cap2}"]
+                m, command="CAP", params=[ANYSTR, "NAK", StrRe(f"-{cap2} ?")]
             )
             raise ImplementationChoice(f"Does not support CAP REQ -{cap2}")
 
-        # server-time should be disabled
+        # multi-prefix should be disabled
         self.sendLine(1, "CAP LIST")
         messages = self.getMessages(1)
         cap_list = [m for m in messages if m.command == "CAP"][0]