--- a/scripts/audio/@audioplayer/__get_properties__.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/__get_properties__.m	Thu Dec 30 16:11:55 2021 -0800
@@ -32,44 +32,36 @@
 
 function props = __get_properties__ (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
-  if (__player_isplaying__ (struct (player).player))
-    running = "on";
-  else
-    running = "off";
-  endif
+  hplayer = struct (player).player;
 
   props = struct ("BitsPerSample",
-                  __player_get_nbits__ (struct (player).player),
+                  __player_get_nbits__ (hplayer),
 
                   "CurrentSample",
-                  __player_get_sample_number__ (struct (player).player),
+                  __player_get_sample_number__ (hplayer),
 
                   "DeviceID",
-                  __player_get_id__ (struct (player).player),
+                  __player_get_id__ (hplayer),
 
                   "NumberOfChannels",
-                  __player_get_channels__ (struct (player).player),
+                  __player_get_channels__ (hplayer),
 
                   "Running",
-                  running,
+                  ifelse (__player_isplaying__ (hplayer), "on", "off"),
 
                   "SampleRate",
-                  __player_get_fs__ (struct (player).player),
+                  __player_get_fs__ (hplayer),
 
                   "TotalSamples",
-                  __player_get_total_samples__ (struct (player).player),
+                  __player_get_total_samples__ (hplayer),
 
                   "Tag",
-                  __player_get_tag__ (struct (player).player),
+                  __player_get_tag__ (hplayer),
 
                   "Type",
                   "audioplayer",
 
                   "UserData",
-                  __player_get_userdata__ (struct (player).player));
+                  __player_get_userdata__ (hplayer));
 
 endfunction

--- a/scripts/audio/@audioplayer/audioplayer.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/audioplayer.m	Thu Dec 30 16:11:55 2021 -0800
@@ -125,15 +125,22 @@
     elseif (nargin == 2)
       recorder = varargin{1};
       data = getaudiodata (recorder);
-      player = audioplayer (data, get (recorder, "SampleRate"),
-                            get (recorder, "BitsPerSample"), varargin{2});
+      player = audioplayer (data,
+                            get (recorder, "SampleRate"),
+                            get (recorder, "BitsPerSample"),
+                            varargin{2});
     else
       print_usage ();
     endif
   else
-    if (ischar (varargin{1}))
-      varargin{1} = str2func (varargin{1});
+    ## FIXME: Prevent use of callbacks until situation is fixed.
+    if (is_function_handle (varargin{1}) || ischar (varargin{1}))
+      error ("audioplayer: first argument cannot be a callback function");
     endif
+    ## FIXME: Uncomment when callback functions are supported.
+    ## if (ischar (varargin{1}))
+    ##   varargin{1} = str2func (varargin{1});
+    ## endif
     player.player = __player_audioplayer__ (varargin{:});
     player = class (player, "audioplayer");
   endif
@@ -142,6 +149,7 @@
 
 
 %!demo
+%! ## Generate 2 seconds of white noise and play it back with a pause
 %! fs = 44100;
 %! audio = 0.25 * randn (2, 2*fs);
 %! player = audioplayer (audio, fs);
@@ -169,37 +177,34 @@
 %! assert (player2.TotalSamples, 44100);
 
 %!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
-%! audio = 0.25 * randn (2, 44100);
-%! fs = 44100;
-%! player = audioplayer (audio, fs);
-%! set (player, {"SampleRate", "Tag", "UserData"}, {8000, "tag", [1, 2; 3, 4]});
-%! assert (player.SampleRate, 8000);
-%! assert (player.Tag, "tag");
-%! assert (player.UserData, [1, 2; 3, 4]);
-
-%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
-%! audio = 0.25 * randn (2, 44100);
+%! audio = randn (8000, 1);
 %! fs = 44100;
-%! player = audioplayer (audio, fs);
-%! settable = set (player);
-%! settable.SampleRate = 8000;
-%! settable.Tag = "tag";
-%! settable.UserData = [1, 2; 3, 4];
-%! set (player, settable);
-%! assert (player.SampleRate, 8000);
-%! assert (player.Tag, "tag");
-%! assert (player.UserData, [1, 2; 3, 4]);
+%! player = audioplayer (audio, fs, 16);
+%! assert (player.NumberOfChannels, 1);
+%! assert (player.SampleRate, 44100);
+%! assert (player.BitsPerSample, 16);
+
+## FIXME: Callbacks do not work currently (5/31/2020) so BIST tests commented.
+%!#function [sound, status] = callback (samples)
+%!#  sound = rand (samples, 2) - 0.5;
+%!#  status = 0;
+%!#endfunction
 
-%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
-%! audio = 0.25 * randn (2, 44100);
-%! fs = 44100;
-%! player = audioplayer (audio, fs);
-%! player.SampleRate = 8000;
-%! player.Tag = "tag";
-%! player.UserData = [1, 2; 3, 4];
-%! properties = get (player, {"SampleRate", "Tag", "UserData"});
-%! assert (properties, {8000, "tag", [1, 2; 3, 4]});
+%!#testif HAVE_PORTAUDIO
+%!# player = audioplayer (@callback, 44100);
+%!# play (player);
+%!# pause (2);
+%!# stop (player);
+%!# assert (1);
 
+%!#testif HAVE_PORTAUDIO
+%!# player = audioplayer ("callback", 44100, 16);
+%!# play (player);
+%!# pause (2);
+%!# stop (player);
+%!# assert (1);
+
+## Verify input validation
 %!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
 %! ## Verify nbits option only accepts 8, 16, 24
 %! fail ("audioplayer (1, 8e3, 9)", "NBITS must be 8, 16, or 24");
@@ -208,22 +213,5 @@
 %! player = audioplayer (1, 8e3, 16);
 %! player = audioplayer (1, 8e3, 24);
 
-## FIXME: Callbacks do not work currently (5/31/2020) so BIST tests commented.
-#%!function [sound, status] = callback (samples)
-#%!  sound = rand (samples, 2) - 0.5;
-#%!  status = 0;
-#%!endfunction
-
-#%!testif HAVE_PORTAUDIO
-#%! player = audioplayer (@callback, 44100);
-#%! play (player);
-#%! pause (2);
-#%! stop (player);
-#%! assert (1);
-
-#%!testif HAVE_PORTAUDIO
-#%! player = audioplayer ("callback", 44100, 16);
-#%! play (player);
-#%! pause (2);
-#%! stop (player);
-#%! assert (1);
+%!error <first argument cannot be a callback> audioplayer (@ls, 8000)
+%!error <first argument cannot be a callback> audioplayer ("ls", 8000)

--- a/scripts/audio/@audioplayer/disp.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/disp.m	Thu Dec 30 16:11:55 2021 -0800
@@ -31,13 +31,13 @@
 
 function disp (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
   printf ("audioplayer object with properties:\n\n");
   for [val, prop] = __get_properties__ (player)
     printf ("  %s = ", prop), disp (val);
   endfor
 
 endfunction
+
+
+## No tests possible/needed for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/get.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/get.m	Thu Dec 30 16:11:55 2021 -0800
@@ -37,28 +37,62 @@
 ## @seealso{@audioplayer/set, @audioplayer/audioplayer}
 ## @end deftypefn
 
-function retval = get (varargin)
+function value = get (player, name)
 
-  if (nargin < 1 || nargin > 2)
-    print_usage ();
-  endif
-
-  properties = __get_properties__ (varargin{1});
+  properties = __get_properties__ (player);
 
   if (nargin == 1)
-    retval = properties;
+    value = properties;
   elseif (nargin == 2)
-    pnames = varargin{2};
+    pnames = name;
     if (ischar (pnames))
-      retval = getfield (properties, pnames);
+      value = getproperty (properties, pnames);
     elseif (iscellstr (pnames))
-      retval = cell (size (pnames));
+      value = cell (size (pnames));
       for i = 1:numel (pnames)
-        retval{i} = getfield (properties, pnames{i});
+        value{i} = getproperty (properties, pnames{i});
       endfor
     else
-      error ("@audioplayer/get: invalid NAME argument");
+      error ("@audioplayer/get: NAME must be a string or cell array of strings");
     endif
   endif
 
 endfunction
+
+function value = getproperty (properties, pname)
+
+  persistent valid_props;
+  if (isempty (valid_props))
+    valid_props = { "BitsPerSample", "CurrentSample", "DeviceID", ...
+                    "NumberOfChannels", "Running", "SampleRate", ...
+                    "TotalSamples", "Tag", "Type", "UserData" };
+  endif
+
+  idx = find (strcmpi (pname, valid_props), 1);
+  if (isempty (idx))
+    error ('@audioplayer/get: "%s" is not a valid property name', pname);
+  endif
+
+  value = properties.(valid_props{idx});
+
+endfunction
+
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! props = get (player);
+%! assert (fieldnames (props), {"BitsPerSample"; "CurrentSample"; "DeviceID";
+%!         "NumberOfChannels"; "Running"; "SampleRate"; "TotalSamples"; "Tag";
+%!         "Type"; "UserData"});
+%! value = get (player, "Running");
+%! assert (value, "off");
+%! value = get (player, "ruNNIng");  # test case insensitivity
+%! assert (value, "off");
+%! values = get (player, {"SampleRate", "BitsPerSample", "TotalSamples"});
+%! assert (values, {44100, 8, 2});
+
+## Test input validation
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! fail ("get (player, 1)", "NAME must be a string");
+%! fail ('get (player, "foobar")', '"foobar" is not a valid property');

--- a/scripts/audio/@audioplayer/isplaying.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/isplaying.m	Thu Dec 30 16:11:55 2021 -0800
@@ -32,10 +32,11 @@
 
 function tf = isplaying (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
   tf = __player_isplaying__ (struct (player).player);
 
 endfunction
+
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (1) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! assert (isplaying (player), false);

--- a/scripts/audio/@audioplayer/pause.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/pause.m	Thu Dec 30 16:11:55 2021 -0800
@@ -31,10 +31,10 @@
 
 function pause (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
   __player_pause__ (struct (player).player);
 
 endfunction
+
+
+## No tests possible for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/play.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/play.m	Thu Dec 30 16:11:55 2021 -0800
@@ -38,12 +38,18 @@
 ## @audioplayer/audioplayer}
 ## @end deftypefn
 
-function play (varargin)
+function play (player, length)
+
+  hplayer = struct (player).player;
 
-  if (nargin < 1 || nargin > 2)
-    print_usage ();
+  if (nargin == 1)
+    __player_play__ (hplayer);
+  else
+    __player_play__ (hplayer, length);
   endif
 
-  __player_play__ (struct (varargin{1}).player, varargin{2:end});
+endfunction
+
 
-endfunction
+## No tests possible for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/playblocking.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/playblocking.m	Thu Dec 30 16:11:55 2021 -0800
@@ -31,7 +31,7 @@
 ## (synchronous I/O).
 ##
 ## If the optional argument @var{start} is provided, begin playing
-## @var{start} samples in to the recording.
+## @var{start} samples into the recording.
 ##
 ## If the optional argument @var{end} is provided, stop playing at
 ## @var{end} samples into the recording.
@@ -39,12 +39,16 @@
 ## @audioplayer/audioplayer}
 ## @end deftypefn
 
-function playblocking (varargin)
+function playblocking (player, length)
 
-  if (nargin < 1 || nargin > 2)
+  if (nargin != 2)
     print_usage ();
   endif
 
-  __player_playblocking__ (struct (varargin{1}).player, varargin{2:end});
+  __player_playblocking__ (struct (player).player, length);
 
 endfunction
+
+
+## No tests possible for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/resume.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/resume.m	Thu Dec 30 16:11:55 2021 -0800
@@ -31,10 +31,10 @@
 
 function resume (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
   __player_resume__ (struct (player).player);
 
 endfunction
+
+
+## No tests possible for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/set.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/set.m	Thu Dec 30 16:11:55 2021 -0800
@@ -38,49 +38,81 @@
 ## @seealso{@audioplayer/get, @audioplayer/audioplayer}
 ## @end deftypefn
 
-function properties = set (varargin)
+function properties = set (player, varargin)
 
-  if (nargin < 1 || nargin > 3)
+  if (nargin > 3)
     print_usage ();
   endif
 
-  player = struct (varargin{1}).player;
+  hplayer = struct (player).player;
 
   if (nargin == 1)
-    properties.SampleRate = {};
-    properties.Tag = {};
-    properties.UserData = {};
+    properties = struct ("SampleRate", {{}}, "Tag", {{}}, "UserData", {{}});
   elseif (nargin == 2)
-    for [value, property] = varargin{2}
-      setproperty (player, property, value);
+    for [value, property] = varargin{1}
+      setproperty (hplayer, property, value);
     endfor
   elseif (nargin == 3)
-    if (iscell (varargin{2}))
+    if (iscell (varargin{1}))
       index = 1;
-      for property = varargin{2}
-        setproperty (player, char (property), varargin{3}{index});
+      for property = varargin{1}
+        setproperty (hplayer, char (property), varargin{2}{index});
         index += 1;
       endfor
     else
-      setproperty (player, varargin{2}, varargin{3});
+      setproperty (hplayer, varargin{1}, varargin{2});
     endif
-  else
-    error ("@audioplayer/set: wrong number of arguments to the set method");
   endif
 
 endfunction
 
 function setproperty (player, property, value)
 
-  switch (property)
-    case "SampleRate"
+  switch (lower (property))
+    case "samplerate"
       __player_set_fs__ (player, value);
-    case "Tag"
+    case "tag"
       __player_set_tag__ (player, value);
-    case "UserData"
+    case "userdata"
       __player_set_userdata__ (player, value);
     otherwise
-      error ("audioplayer: no such property or the property specified is read-only");
+      error ('@audioplayer/set: "%s" is not a valid property name or is read-only', property);
   endswitch
 
 endfunction
+
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! set (player, "SampleRate", 8800);
+%! set (player, "Tag", "mytag");
+%! ## Also test case insensitivity
+%! set (player, "USERdata", [1, 2; 3, 4]);
+%! assert (player.SampleRate, 8800);
+%! assert (player.Tag, "mytag");
+%! assert (player.UserData, [1, 2; 3, 4]);
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! set (player, {"SampleRate", "Tag", "UserData"},
+%!              {8800, "mytag", [1, 2; 3, 4]});
+%! assert (player.SampleRate, 8800);
+%! assert (player.Tag, "mytag");
+%! assert (player.UserData, [1, 2; 3, 4]);
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! props = set (player);
+%! props.SampleRate = 8800;
+%! props.Tag = "mytag";
+%! props.UserData = [1, 2; 3, 4];
+%! set (player, props);
+%! assert (player.SampleRate, 8800);
+%! assert (player.Tag, "mytag");
+%! assert (player.UserData, [1, 2; 3, 4]);
+
+## Test input validation
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! fail ('set (player, "foobar", 1)', "not a valid property name"); 
+%! fail ('set (player, "Running", 1)', "is read-only"); 

--- a/scripts/audio/@audioplayer/stop.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/stop.m	Thu Dec 30 16:11:55 2021 -0800
@@ -32,10 +32,10 @@
 
 function stop (player)
 
-  if (nargin < 1)
-    print_usage ();
-  endif
-
   __player_stop__ (struct (player).player);
 
 endfunction
+
+
+## No tests possible for this function
+%!assert (1)

--- a/scripts/audio/@audioplayer/subsasgn.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/subsasgn.m	Thu Dec 30 16:11:55 2021 -0800
@@ -33,6 +33,10 @@
 
 function value = subsasgn (player, idx, rhs)
 
+  if (nargin != 3)
+    print_usage ();
+  endif
+
   if (isempty (idx))
     error ("audioplayer: missing index");
   endif
@@ -46,3 +50,15 @@
   endif
 
 endfunction
+
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! player.Tag = "mytag";
+%! assert (get (player, "Tag"), "mytag");
+
+## Test input validation
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! fail ("player(1).Tag = 5", "invalid subscript type");
+%! fail ("player{1}.Tag = 5", "invalid subscript type");

--- a/scripts/audio/@audioplayer/subsref.m	Thu Dec 30 11:42:19 2021 -0800
+++ b/scripts/audio/@audioplayer/subsref.m	Thu Dec 30 16:11:55 2021 -0800
@@ -49,3 +49,15 @@
   endif
 
 endfunction
+
+
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! set (player, "Tag", "mytag");
+%! assert (player.Tag, "mytag");
+
+## Test input validation
+%!testif HAVE_PORTAUDIO; audiodevinfo (0) > 0
+%! player = audioplayer ([-1, 1], 44100, 8);
+%! fail ("player(1).Tag", "invalid subscript type");
+%! fail ("player{1}.Tag", "invalid subscript type");