diff --git a/+hw/+ptb/Window.m b/+hw/+ptb/Window.m
index 9e3b1de6..24753d7c 100644
--- a/+hw/+ptb/Window.m
+++ b/+hw/+ptb/Window.m
@@ -547,14 +547,17 @@ function fillRect(obj, colour, rect)
       Screen('PreloadTextures', obj.PtbHandle, tex);
     end
 
-    function [nx, ny] = drawText(obj, text, x, y, colour, vSpacing, wrapAt)
+    function [nx, ny] = drawText(obj, text, varargin)
       % DRAWTEXT Draw some text to the screen
+      %  [NX, NY] = DRAWTEXT(OBJ, TEXT, X, Y, COLOUR, TEXTSIZE, VSPACING, WRAPAT)
       %  The outputs may be used as the new start positions to draw further
       %  text to the screen.
       %  
       %  Inputs:
       %    text (char) - The text to be written to screen.  May contain
       %      newline characters '\n'.
+      %
+      %  Inputs (Optional):
       %    x (numerical|char) - The top-left x coordinate of the text in
       %      px.  If empty the left-most area part of the screen is used.
       %      May also be one of the following string options: 'center',
@@ -565,9 +568,12 @@ function fillRect(obj, colour, rect)
       %    color - The CLUT index for the text (scalar, RGB or RGBA vector)
       %      If color is left out, the current text color from previous
       %      text drawing commands is used.
-      %    vSpacing - The spacing between the lines in px. Defaults to 1.
-      %    wrapAt (char) - automatically break text longer than this string 
-      %      into newline separated strings of roughly the same length
+      %    textSize (numerical) - The size of the text in px.  Defaults to
+      %      PTB current setting (usually the system default).
+      %    vSpacing (numerical) - The spacing between the lines in px. 
+      %      Defaults to 1.
+      %    wrapAt (numerical) - Automatically break text longer than this 
+      %      number of chars.
       %
       %  Outputs:
       %    nx - The approximate x-coordinate of the 'cursor position' in px
@@ -580,23 +586,32 @@ function fillRect(obj, colour, rect)
       %    obj.flip()
       %
       % See also DRAWFORMATTEDTEXT, DRAWTEXTURE, WRAPSTRING
-      if nargin < 7
-        wrapAt = [];
-      end
-      if nargin < 6
-        vSpacing = [];
-      end
-      if nargin < 5
-        colour = [];
-      end
-      if nargin < 4
-        y = [];
-      end
-      if nargin < 3
-        x = [];
-      end
-      [nx, ny] = DrawFormattedText(obj.PtbHandle, text, x, y, colour, wrapAt, [], [],...
-        vSpacing);
+      
+      p = inputParser;
+      p.addRequired('text', @ischar)
+      p.addOptional('x', [], @(x) ischar(x) || isnumeric(x))
+      p.addOptional('y', [], @(x) ischar(x) || isnumeric(x))
+      p.addOptional('colour', [], @isnumeric)
+      p.addOptional('textSize', ...
+        Screen('TextSize', obj.PtbHandle), ...
+        @(x) isnumeric(x) || isscalar(x))
+      p.addOptional('vSpacing', [], @(x) isnumeric(x) || isscalar(x))
+      p.addOptional('wrapAt', [], @isnumeric)
+      p.parse(text, varargin{:})
+      p = p.Results;
+      
+      % Set text size or restore to default on exit
+      oldTextSize = Screen('TextSize', obj.PtbHandle, p.textSize);
+      mess = onCleanup(@() Screen('TextSize', obj.PtbHandle, oldTextSize));
+      
+      % Draw the text to screen
+      [nx, ny] = DrawFormattedText(...
+        obj.PtbHandle, ...
+        p.text, ...
+        p.x, p.y, ...
+        p.colour, ...
+        p.wrapAt, [], [],...
+        p.vSpacing);
 %       Screen('DrawText', obj.PtbHandle, text, x, y, colour, [], real(yPosIsBaseline));
     end
 
diff --git a/+hw/debugWindow.m b/+hw/debugWindow.m
index a6908249..e32d7bb1 100644
--- a/+hw/debugWindow.m
+++ b/+hw/debugWindow.m
@@ -3,38 +3,54 @@
 %   Uses Psychtoolbox to open and control an on-screen window that is
 %   useful for debugging. Also returns a dummy viewing model.
 %
+%   Input (Optional):
+%     open (logical): Immediately open the PTB window after instantiating.
+%       Default true.
+%
+%   Outputs:
+%     window (hw.ptb.Window): A Window object configured for a 800x600
+%       stimulus screen, with PTB warning and sync tests supressed.
+%     viewingModel (hw.BasicScreenViewingModel): A ViewingModel object
+%       configured for a subject positioned squarely in front of the
+%       window, 7cm away.
+%
+%   Example:
+%     % Open a window for testing and set to middle grey
+%     win = hw.debugWindow;
+%     win.BackgroundColour = 255/2;
+%     win.flip();
+%
+%   Example:
+%     % Save the debug window and model into a test rig's hardware file
+%     [stimWindow, stimViewingModel] = hw.debugWindow(false);
+%     hwPath = getOr(dat.paths('testRig', 'rigConfig'));
+%     save(fullfile(hwPath, 'hardware.mat'), 'stim*', '-append')
+%
+% See also hw.ptb.Window, PsychDebugWindowConfiguration
+%
 % Part of Rigbox
 
 % 2012-10 CB created
 
-if nargin < 1
-  open = true;
-end
+% Default is to immediately open the window
+if nargin < 1, open = true; end
 
+% Set some reasonable parameters for the window (800x600 resolution)
 pixelWidth = 800;
 pixelHeight= 600;
-viewWidth = 0.2;
+viewWidth = 0.2; % Assume window is 200mm wide on the screen
 viewHeight = viewWidth*pixelHeight/pixelWidth;
 
-% oldSyncTests = Screen('Preference', 'SkipSyncTests', 2);
-% oldVerbosity = Screen('Preference', 'Verbosity', 0);
-% cleanup1 = onCleanup(@() Screen('Preference', 'SkipSyncTests', oldSyncTests));
-% cleanup2 = onCleanup(@() Screen('Preference', 'Verbosity', oldVerbosity));
-
+% Create the window object
 window = hw.ptb.Window;
-window.PtbVerbosity = 0;
-window.PtbSyncTests = 2;
+window.PtbVerbosity = 0; % Supress warnings
+window.PtbSyncTests = 2; % Supress sync tests (always fail when windowed)
 window.OpenBounds = SetRect(50, 50, pixelWidth+50, pixelHeight+50);
+if open, window.open(); end % Open now if open == true
 
-if open
-  window.open();
-end
-
-
+% Create the viewing model
 viewingModel = hw.BasicScreenViewingModel;
 viewingModel.ScreenWidthPixels = pixelWidth;
 viewingModel.ScreenWidthMetres = viewWidth;
 viewingModel.SubjectPos = [.5*viewWidth .5*viewHeight .07];
 
-end
-
diff --git a/+srv/expServer.m b/+srv/expServer.m
index 0af48923..030a203b 100644
--- a/+srv/expServer.m
+++ b/+srv/expServer.m
@@ -26,6 +26,8 @@ function expServer(varargin)
 %       database.  This parameter is only used with the 'expRef' parameter.
 %
 %   Key bindings:
+%     q - Quit expServer.
+%     h - View list of key bindings.
 %     t - Toggle Timeline on and off.  The default state is defined in the
 %       hardware file but may be overridden as the first input argument.
 %     w - Toggle reward on and off.  This switches the output of the first
@@ -34,9 +36,12 @@ function expServer(varargin)
 %       file.
 %     space - Deliver default reward, specified by the DefaultCommand
 %       property in the hardware file.
-%     m - Perform water calibration. 
+%     m - Perform reward calibration for the current reward controller.
+%     v - View the current water calibration for current reward controller.
 %     b - Toggle the background colour between the default and white.
 %     g - Perform gamma correction
+%     1 - Select first reward controller.
+%     2 - Select second reward controller.
 %     
 %   Example 1: Run in listener mode with Timeline disabled
 %     srv.expServer('UseTimelineOverride', false)
@@ -53,13 +58,20 @@ function expServer(varargin)
 
 %% Fixed Parameters
 global AGL GL GLU %#ok<NUSED>
-quitKey = KbName('q');
-rewardToggleKey = KbName('w');
-rewardPulseKey = KbName('space');
-rewardCalibrationKey = KbName('m');
-gammaCalibrationKey = KbName('g');
-timelineToggleKey = KbName('t');
-toggleBackground = KbName('b');
+key = struct(...
+  'quit', KbName('q'), ...
+  'help', KbName('h'), ...
+  'rewardToggle', KbName('w'), ...
+  'rewardPulse', KbName('space'), ...
+  'rewardCalibration', KbName('m'), ...
+  'viewCalibration', KbName('v'), ...
+  'gammaCalibration', KbName('g'), ...
+  'timelineToggle', KbName('t'), ...
+  'toggleBackground', KbName('b'), ...
+  'selectFirst', KbName('1'), ...
+  'selectSecond', KbName('2'));
+
+rewardId = 1;
 % Function for constructing a full ID for warnings and errors
 fullID = @(id) strjoin([{'Rigbox:srv:expServer'}, ensureCell(id)],':');
 
@@ -151,11 +163,8 @@ function expServer(varargin)
 rig.stimWindow.BackgroundColour = bgColour;
 rig.stimWindow.open();
 
-fprintf('\n<q> quit, <w> toggle reward, <t> toggle timeline\n');
-fprintf(['<%s> reward pulse, <%s> perform reward calibration\n' ...
-  '<%s> perform gamma calibration\n'], KbName(rewardPulseKey), ...
-  KbName(rewardCalibrationKey), KbName(gammaCalibrationKey));
-log('Started presentation server on port %i', communicator.DefaultListenPort);
+fprintf('\n<%s> quit, <%s> help\n', key.quit, key.help);
+log('Started presentation server on port %i', communicator.DefaultListenPort)
 
 if nargin < 1 || isempty(p.useTimelineOverride)
   % toggle use of timeline according to rig default setting
@@ -170,6 +179,7 @@ function expServer(varargin)
     'Experiment ref ''%s'' does not exist', p.expRef)
   runExp(p.expRef, p.preDelay, p.postDelay, p.alyx);
 end
+calibrationDisplayed = false;
 
 %% Main loop for service
 running = ~singleShot;
@@ -183,19 +193,24 @@ function expServer(varargin)
   [~, firstPress] = KbQueueCheck;
   
   % check if the quit key was pressed
-  if firstPress(quitKey) > 0
-    log('Quitting (quit key pressed)');
+  if firstPress(key.quit) > 0
+    log('Quitting (quit key pressed)')
     running = false;
   end
   
+  % check if help key was pressed
+  if firstPress(key.help) > 0
+    showHelp();
+  end
+  
   % check if the quit key was pressed
-  if firstPress(timelineToggleKey) > 0
+  if firstPress(key.timelineToggle) > 0
     toggleTimeline();
   end
   
   % check for reward toggle
-  if firstPress(rewardToggleKey) > 0
-    log('Toggling reward valve');
+  if firstPress(key.rewardToggle) > 0
+    log('Toggling reward valve')
     curr = rig.daqController.Value(rewardId);
     sig = rig.daqController.SignalGenerators(rewardId);
     if curr == sig.OpenValue
@@ -206,36 +221,42 @@ function expServer(varargin)
   end
   
   % check for reward pulse
-  if firstPress(rewardPulseKey) > 0
+  if firstPress(key.rewardPulse) > 0
     log('Delivering default reward');
     def = [rig.daqController.SignalGenerators(rewardId).DefaultCommand];
     rig.daqController.command(def);
   end
   
   % check for reward calibration
-  if firstPress(rewardCalibrationKey) > 0
-    log('Performing a reward delivery calibration');
+  if firstPress(key.rewardCalibration) > 0
+    log('Performing a reward delivery calibration')
     calibrateWaterDelivery();
   end
   
-  % check for gamma calibration
-  if firstPress(gammaCalibrationKey) > 0
-      log('Performing a gamma calibration');
-      calibrateGamma();
+  % check for view calibration
+  if firstPress(key.viewCalibration) > 0
+    calibrationDisplayed = ~calibrationDisplayed;
+    iff(calibrationDisplayed, @() viewWaterCalibration, @() rig.stimWindow.flip)
   end
   
-  if firstPress(toggleBackground) > 0
-      log('Changing background to white');
-      whiteScreen();
+  % check for gamma calibration
+  if firstPress(key.gammaCalibration) > 0
+    log('Performing a gamma calibration')
+    calibrateGamma();
   end
   
-  if firstPress(KbName('1')) > 0
-    rewardId = 1;
-  end
-  if firstPress(KbName('2')) > 0
-    rewardId = 2;
+  if firstPress(key.toggleBackground) > 0
+    log('Changing background to white')
+    % WHITESCREEN Changes screen background to white
+    rig.stimWindow.BackgroundColour = rig.stimWindow.White;
+    rig.stimWindow.flip();
+    rig.stimWindow.BackgroundColour = bgColour;
   end
   
+  % Toggle reward ID
+  if firstPress(key.selectFirst) > 0, rewardId = 1; end
+  if firstPress(key.selectSecond) > 0, rewardId = 2; end
+  
   % pause a little while to allow other OS processing
   pause(5e-3);
 end
@@ -362,7 +383,7 @@ function handleMessage(id, data, host)
     fid = fopen(hwInfo, 'w');
     fprintf(fid, '%s', obj2json(rig));
     fclose(fid);
-    if ~strcmp(dat.parseExpRef(expRef), 'default') && ~isempty(getOr(dat.paths, 'databaseURL'))
+    if ~strcmp(dat.parseExpRef(expRef), 'default') && ~isempty(getOr(rig.paths, 'databaseURL'))
       try
         alyx.registerFile(hwInfo);
       catch ex
@@ -381,27 +402,107 @@ function handleMessage(id, data, host)
   end
 
   function calibrateWaterDelivery()
+    % CALIBRATEWATERDELIVERY Performs measured reward deliveries for calibration
+    %   Runs a water calibration for the currently selected reward ID,
+    %   saves to the hardware file and displays a plot of the calibration.
+    %
+    % See also viewWaterCalibration, hw.calibrate
+    assert(isfield(rig, 'scale'), fullID('noScaleObject'), ...
+      'reward calibrations require a scale object in the hardware file')
     daqController = rig.daqController;
     chan = daqController.ChannelNames(rewardId);
-    %perform measured deliveries
+    
+    % Perform measured deliveries
     rig.scale.init();
     calibration = hw.calibrate(chan, daqController, rig.scale, 20e-3, 150e-3);
     rig.scale.cleanup();
-    %different delivery durations appear in each column, repeats in each row
-    %from the data, make a measuredDelivery structure
-    ul = [calibration.volumeMicroLitres];
-    log('Delivered volumes ranged from %.1ful to %.1ful', min(ul), max(ul));
     
-    rigHwFile = fullfile(pick(dat.paths, 'rigConfig'), 'hardware.mat');
+    % Different delivery durations appear in each column, repeats in each
+    % row from the data, make a measuredDelivery structure
+    ul = [calibration.volumeMicroLitres];
+    log('Delivered volumes ranged from %.1ful to %.1ful', min(ul), max(ul))
     
+    % Save the calibration into the rig hardware file
+    rigHwFile = fullfile(rig.paths.rigConfig, 'hardware.mat');
     save(rigHwFile, 'daqController', '-append');
+    
+    % Show a plot of the new calibration
+    viewWaterCalibration()
+    calibrationDisplayed = true;
   end
 
-  function whiteScreen()
-    % WHITESCREEN Changes screen background to white
-    rig.stimWindow.BackgroundColour = rig.stimWindow.White;
+  function viewWaterCalibration()
+    % VIEWWATERCALIBRATION Displays a plot of the most recent reward calibration
+    %  Prints a plot of valve open time vs reward volume from the last
+    %  saved calibration of the currently selected reward controller.
+    %
+    % See also calibrateWaterDelivery
+    
+    % Check if calibration is available for current reward Signal Generator
+    sigGens = rig.daqController.SignalGenerators;
+    noCalibration = ...
+      rewardId > length(sigGens) || ...
+      ~isprop(sigGens(rewardId), 'Calibrations') || ...
+      isempty(sigGens(rewardId).Calibrations);
+    
+    if noCalibration
+      % If empty, log missing calibration and return.
+      log('No reward calibration found for reward controller')
+      return
+    end
+    
+    % Fetch the most recent calibration
+    log('Displaying calibration')
+    [newestDate, I] = max([sigGens(rewardId).Calibrations.dateTime]);
+    c = sigGens(rewardId).Calibrations(I);
+    
+    % Create a figure and plot the data
+    fig = figure('Color', 'w', 'Visible', 'off');
+    plot([c.measuredDeliveries.durationSecs], ...
+         [c.measuredDeliveries.volumeMicroLitres], 'x-');
+    
+    % Set some labels, etc.
+    xlabel('Duration (sec)');
+    ylabel('Volume (\muL)');
+    set(gca, 'FontSize', 16, 'YLim', [0 5])
+    title(datestr(newestDate))
+    
+    % Draw the plot to the screen
+    cdata = getOr(getframe(fig), 'cdata'); % Get the cdata from the plot
+    imageDisplay = rig.stimWindow.makeTexture(cdata); % Load texture
+    rig.stimWindow.BackgroundColour = rig.stimWindow.White; % Match background
+    rig.stimWindow.drawTexture(imageDisplay); % Draw plot texture
+    rig.stimWindow.flip; % Show on screen
+    rig.stimWindow.BackgroundColour = bgColour; % Restore background colour
+    close(fig) % Close our invisible figure
+  end
+
+  function showHelp()
+    % VIEWHELP Print the hotkeys for expServer
+    %   Displays the list of keys and their functions to the log and to the
+    %   Stimulus Window.
+    
+    % Convert key codes to key names
+    keyNames = mapToCell(@KbName, struct2cell(key));
+    msg = sprintf(['Displaying help\n\r',...
+      '<%s> quit \n', ...
+      '<%s> help \n', ...
+      '<%s> toggle reward \n', ...
+      '<%s> reward pulse \n', ...
+      '<%s> perform reward calibration \n', ...
+      '<%s> view reward calibration \n', ...
+      '<%s> perform gamma calibration \n', ...
+      '<%s> toggle timeline \n', ...
+      '<%s> toggle white screen \n', ...
+      '<%s> select 1st reward controller \n', ...
+      '<%s> select 2nd reward controller'], keyNames{:});
+    
+    % Draw white text to centre of screen at 40 chars per line, 1px
+    % spacing, 20px text size
+    w = rig.stimWindow.White; % Set a white background
+    rig.stimWindow.drawText(msg, 'centerblock', 'center', w, 20, 1, 40);
     rig.stimWindow.flip();
-    rig.stimWindow.BackgroundColour = bgColour;
+    log(msg) % Display in command window too
   end
 
   function calibrateGamma()
@@ -445,7 +546,7 @@ function saveGamma(cal)
     % SAVEGAMMA Save calibration struct to saved stimWindow object
     %  Loads saved stimWindow object from this rig's hardware file, updates
     %  the Calibration property with input, then saves.
-    rigHwFile = fullfile(pick(dat.paths, 'rigConfig'), 'hardware.mat');
+    rigHwFile = fullfile(rig.paths.rigConfig, 'hardware.mat');
     stimWindow = load(rigHwFile,'stimWindow');
     stimWindow = stimWindow.stimWindow;
     stimWindow.Calibration = cal;
diff --git a/tests/checkCoverage.m b/tests/checkCoverage.m
index a14eeab9..73dc5650 100644
--- a/tests/checkCoverage.m
+++ b/tests/checkCoverage.m
@@ -21,6 +21,8 @@
   % Try to divine test function location
   funLoc = fileparts(which(erase(testFile,'_test')));
 end
+assert(~isempty(funLoc), ...
+  'Failed to find file/package under test, please provide the location')
 import matlab.unittest.TestRunner
 import matlab.unittest.plugins.CodeCoveragePlugin
 runner = TestRunner.withTextOutput;
diff --git a/tests/expServer_test.m b/tests/expServer_test.m
index 506b3223..ed56171b 100644
--- a/tests/expServer_test.m
+++ b/tests/expServer_test.m
@@ -37,11 +37,6 @@ function setupFolder(testCase)
       assert(mkdir(fullfile(mainRepo, 'test')), ...
         'Failed to create subject folder')
             
-      % Save a custom path disabling Alyx
-      paths.databaseURL = [];
-      configDir = getOr(dat.paths, 'rigConfig');
-      save(fullfile(configDir, 'paths.mat'), 'paths')
-      
       % Alyx queue location
       qDir = getOr(dat.paths, 'localAlyxQueue');
       assert(mkdir(qDir), 'Failed to create alyx queue')
@@ -75,6 +70,7 @@ function setMockRig(testCase)
         'AddedMethods', methods(exp.Experiment)');
 
       % Inject our mocks via calls to hw.devices
+      testCase.Rig.paths = rmfield(dat.paths, 'databaseURL'); % Add paths to object
       hw.devices('testRig', false, testCase.Rig);
       
       % Set some default behaviours for some of the objects
@@ -95,7 +91,8 @@ function setMockRig(testCase)
 
       % Clear mock histories just to be safe
       clearHistory = @(mock) testCase.clearMockHistory(mock);
-      structfun(@(mock) testCase.addTeardown(clearHistory, mock), testCase.Rig);
+      structfun(@(mock) testCase.addTeardown(clearHistory, mock), ...
+        rmfield(testCase.Rig, 'paths')); % All Rig fields mocks except 'paths'
       testCase.addTeardown(@clear, ...
         'KbQueueCheck', 'configureDummyExperiment', 'devices')
     end
@@ -308,7 +305,7 @@ function test_reward_switch(testCase)
         'ClosedValue', rand);
       generators = [s() s()];
       
-      % Assign output for 'ClosedValue' property
+      % Assign output for 'SignalGenerators' property
       testCase.assignOutputsWhen(...
         get(testCase.RigBehaviours.daqController.SignalGenerators), generators)
       
@@ -456,7 +453,7 @@ function test_alyx(testCase)
       import matlab.mock.actions.Invoke
       
       %%% Test warning free %%%
-      testCase.assertEmpty(getOr(dat.paths, 'databaseURL'), ...
+      testCase.assertEmpty(getOr(testCase.Rig.paths, 'databaseURL'), ...
         'Expected databaseURL field to be unset for this test')
       testCase.verifyWarningFree(@srv.expServer)
       
@@ -471,15 +468,11 @@ function test_alyx(testCase)
       %     - 'Alyx:registerFile:UnableToValidate'
       %     - 'Alyx:flushQueue:NotConnected'
       
-      % Set custom paths.  First add teardown to restore behaviour, then
-      % delete paths file
-      customPath = fullfile(getOr(dat.paths, 'rigConfig'), 'paths.mat');
-      paths.databaseURL = [];
-      testCase.addTeardown(@superSave, customPath, struct('paths', paths))
-      % Remove custom paths
-      delete(customPath)
+      % Add dataseURL back to paths
       testCase.assertNotEmpty(getOr(dat.paths, 'databaseURL'), ...
         'Expected databaseURL field to be unset for this test')
+      testCase.Rig.paths = dat.paths; % Add paths to object
+      hw.devices('testRig', false, testCase.Rig);
       
       % Inject our our mock experiment via function call in srv.prepareExp
       exp.configureDummyExperiment([], [], testCase.Experiment);
@@ -946,6 +939,95 @@ function test_single_shot(testCase)
         experiment.run(inputs.expRef)], ...
         Occurred('RespectingOrder', true))
     end
+      
+    function test_viewHelp(testCase)
+      % Test behaviour when help key pressed.  Help text should be printed
+      % to the command window and to the screen.
+      import matlab.mock.constraints.Occurred
+      % Simulate pressing help key then quit
+      KbQueueCheck(-1, sequence({'h', 'q'}));
+
+      T = evalc('srv.expServer');
+      testCase.verifyMatches(T, 'Displaying help', ...
+        'Failed to print help to the command window')
+      % Retrieve mock history for the Window
+      behaviour = testCase.RigBehaviours.stimWindow;
+      testCase.verifyThat([...
+        get(behaviour.White), ...
+        withAnyInputs(behaviour.drawText),...
+        withAnyInputs(behaviour.flip)], ...
+        Occurred('RespectingOrder', true))
+    end
+    
+    function test_viewCalibration(testCase)
+      % Test behaviour when view calibration key pressed.  The plot should
+      % be printed to the screen if a calibration is available for the
+      % currently selected controller.  NB: Doesn't check whether the most
+      % recent calibration is used.
+      import matlab.mock.constraints.Occurred
+      
+      % Set some calibration data
+      n = 5; % Number of simulated deliveries
+      durationSecs = linspace(20e-3, 150e-3, n);
+      volumeMicroLitres = linspace(0.5, 3.5, n);
+      % Create some generators to test function with.  Unlike those returned by
+      % mockRig, these will be subclasses of the hw.RewardValveControl class and
+      % therefore we can keep them in a heterogeneous array. We must use objects
+      % here as expServer tests for particular properties.
+      generators = hw.RewardValveControl.empty(0,2);
+      calibrations = struct('dateTime', [], 'measuredDeliveries', []);
+      for i = 1:2
+        generators(i) = createMock(testCase, ?hw.RewardValveControl);
+        for j = 1:2
+          % Two calibrations each; one yesterday, one the day before
+          calibrations(i).dateTime = now-i;
+          % Create a 1xn struct of measured deliveries
+          mkStruct = @(a,b)struct('durationSecs',a,'volumeMicroLitres',b);
+          calibrations(i).measuredDeliveries = arrayfun(mkStruct, ...
+            durationSecs, volumeMicroLitres + rand); % Change volumes a bit
+        end
+        generators(i).Calibrations = calibrations; % Assign our calibrations
+      end
+      % Assign generators to daqController mock
+      testCase.assignOutputsWhen(...
+        get(testCase.RigBehaviours.daqController.SignalGenerators), generators)
+            
+      % Simulate pressing view toggle, then switching controller, then quit
+      KbQueueCheck(-1, sequence({'v', 'v', '2', 'v', 'q'}));
+      srv.expServer;
+
+      % Retrieve mock history for the Window
+      behaviour = testCase.RigBehaviours.stimWindow;
+      testCase.verifyThat([...
+        withAnyInputs(behaviour.makeTexture),...
+        withAnyInputs(behaviour.drawTexture),...
+        withAnyInputs(behaviour.flip)], ...
+        Occurred('RespectingOrder', false), 'Failed to print to Window')
+      
+      % Check that both signal generators were check exactly once.  Assumes
+      % that if it check the Calibrations property, it probably used it.
+      for i = 1:2
+        history = testCase.getMockHistory(generators(1));
+        expected = ...
+          numel(history) == 1 && ...
+          isa(history, 'matlab.mock.history.SuccessfulMethodCall') && ...
+          strcmp(history.Name,"findprop") && ...
+          strcmp(history.Inputs{2}, 'Calibrations');
+        testCase.verifyTrue(expected, 'Failed to query reward controller')
+      end
+      
+      % Finally check how it deals with missing reward controllers
+      testCase.clearMockHistory(testCase.Rig.stimWindow)
+      generators(1).Calibrations = []; % No calibrations for controller
+      % Assign only one generator to daqController mock
+      testCase.assignOutputsWhen(...
+        get(testCase.RigBehaviours.daqController.SignalGenerators), generators(1))
+      % Simulate selection of 2nd reward controller
+      KbQueueCheck(-1, sequence({'v', '2', 'v', 'q'}));
+      T = evalc('srv.expServer');
+      testCase.verifyMatches(T, 'No reward calibration')
+      testCase.verifyNotCalled(withAnyInputs(behaviour.drawTexture))
+    end
   end
   
 end
diff --git a/tests/fixtures/+hw/devices.m b/tests/fixtures/+hw/devices.m
index d5107a99..0b8b4b02 100644
--- a/tests/fixtures/+hw/devices.m
+++ b/tests/fixtures/+hw/devices.m
@@ -22,6 +22,7 @@
 if isempty(mockRig)
   mockRig = struct(...
     'name', name, ...
+    'paths', dat.paths, ...
     'clock', hw.ptb.Clock, ...
     'audioDevices', struct(...
         'DeviceName', 'default',...