diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -497,6 +497,12 @@ def vlog(*msg):
 # sans \t, \n and \r
 CDATA_EVIL = re.compile(br"[\000-\010\013\014\016-\037]")
 
+# Match feature conditionalized output lines in the form, capturing the feature
+# list in group 2, and the preceeding line output in group 1:
+#
+#   output..output (feature !)\n
+optline = re.compile(b'(.+) \((.+?) !\)\n$')
+
 def cdatasafe(data):
     """Make a string safe to include in a CDATA block.
 
@@ -1271,8 +1277,19 @@ class TTest(Test):
                     if r:
                         els.pop(i)
                         break
-                    if el and el.endswith(b" (?)\n"):
-                        optional.append(i)
+                    if el:
+                        if el.endswith(b" (?)\n"):
+                            optional.append(i)
+                        else:
+                            m = optline.match(el)
+                            if m:
+                                conditions = [c for c in m.group(2).split(' ')]
+
+                                if self._hghave(conditions)[0]:
+                                    lout = el
+                                else:
+                                    optional.append(i)
+
                     i += 1
 
                 if r:
@@ -1298,8 +1315,10 @@ class TTest(Test):
                 # clean up any optional leftovers
                 while expected.get(pos, None):
                     el = expected[pos].pop(0)
-                    if el and not el.endswith(b" (?)\n"):
-                        break
+                    if el:
+                        if (not optline.match(el)
+                            and not el.endswith(b" (?)\n")):
+                            break
                     postout.append(b'  ' + el)
 
             if lcmd:
@@ -1371,6 +1390,12 @@ class TTest(Test):
             if el.endswith(b" (?)\n"):
                 retry = "retry"
                 el = el[:-5] + b"\n"
+            else:
+                m = optline.match(el)
+                if m:
+                    el = m.group(1) + b"\n"
+                    retry = "retry"
+
             if el.endswith(b" (esc)\n"):
                 if PYTHON3:
                     el = el[:-7].decode('unicode_escape') + '\n'
diff --git a/tests/test-run-tests.t b/tests/test-run-tests.t
--- a/tests/test-run-tests.t
+++ b/tests/test-run-tests.t
@@ -39,6 +39,19 @@ error paths
   $ rm hg
 #endif
 
+Features for testing optional lines
+===================================
+
+  $ cat > hghaveaddon.py <<EOF
+  > import hghave
+  > @hghave.check("custom", "custom hghave feature")
+  > def has_custom():
+  >     return True
+  > @hghave.check("missing", "missing hghave feature")
+  > def has_missing():
+  >     return False
+  > EOF
+
 an empty test
 =======================
 
@@ -67,6 +80,13 @@ a succesful test
   >   def (?)
   >   456 (?)
   >   xyz
+  >   $ printf 'zyx\nwvu\ntsr\n'
+  >   abc (?)
+  >   zyx (custom !)
+  >   wvu
+  >   no_print (no-custom !)
+  >   tsr (no-missing !)
+  >   missing (missing !)
   > EOF
 
   $ rt
@@ -341,6 +361,12 @@ Running In Debug Mode
   xyz
   + echo *SALT* 15 0 (glob)
   *SALT* 15 0 (glob)
+  + printf *zyx\nwvu\ntsr\n* (glob)
+  zyx
+  wvu
+  tsr
+  + echo *SALT* 22 0 (glob)
+  *SALT* 22 0 (glob)
   .
   # Ran 2 tests, 0 skipped, 0 warned, 0 failed.