#define private public - Pasting my own dogfood, part 2 (09 Apr 2006)

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---+++ [[BlogOnSoftware20060409][Pasting my own dogfood, part 2]] (09 Apr 2006)

[[BlogOnSoftware20060409][Yesterday]], I introduced the problem of
how to automatically test Windows clipboard code in applications.
The idea is to move from manual and error-prone clickety-click style
testing to an automatic process which produces reliable results.

<img src="%ATTACHURL%/clipbrdviewer.png" alt="Clipboard viewer" align="right" />
Unbeknownst to many, Windows ships with a fairly interesting tool
called the <nop>ClipBook Viewer (=clipbrd.exe=), which monitors
what the clipboard contains, and will even display the formats
it knows about.

This is quite helpful while developing and debugging clipboard code.
However, <nop>ClipBook Viewer can even help with test automation since it
can save the current clipboard contents to =*.CLP= files and load them
back into the clipboard later.

Which, in fact, is almost all we need to thoroughly and reliably
test clipboard code: We run some apps which produce
a good variety of clipboard formats which our own application needs
to deal with. We select some data, copy them to the clipboard, then 
save the clipboard contents as a =*.CLP= file from <nop>ClipBook Viewer.

Once we have created a reasonably-sized clipboard file library,
we run <nop>ClipBook viewer and load each one of those clipboard
files in turn. After loading, we switch to our own app,
paste the data and check whether the incoming data makes sense to us.
Not bad at all!

But alas, I could not find a way to automate
the <nop>ClipBook Viewer via the command-line or COM interfaces. If someone
knows about such interfaces, I'm certainly most interested to hear about
them.

<img src="%ATTACHURL%/clearclipboard.png" align="right" />
Luck would have it that only recently, I [[BlogOnSoftware20060303][blogged about poor man's automation via <tt>SendKeys</tt>]]. The idea is to write a small shell script
which runs the  target application (here: =clipbrd.exe=), and then simulate how a user
presses keys to use the application.

=clipbrd.exe= can be started with the name of a =*.CLP= file in its
command line, and will then automatically load this file. However,
before it pushes the contents of the file to clipboard, it will
ask the user for confirmation in a message box. Well, in fact, first
it will try to establish <nop>NetDDE connections, and will usually waste
quite a bit of time for this. The following script tries to take this
into account:

<pre>
Set WshShell = WScript.CreateObject("WScript.Shell")
WshShell.Run("clipbrd.exe c:\temp\clip.CLP")
WScript.Sleep 5000 ' Wait for "Clear clipboard (yes/no)?" message box
WshShell.SendKeys "{ENTER}"
</pre>

Now we could add some more scripting glue code to control our own
application, have it execute its "Paste" functionality and verify
that the data arrives in all its expected glory.

The above code is not quite that useful if we need to run
a set of tests in a loop; the following modified version is
better suited for that purpose. It assumes that all =*.CLP=
files are stored in =c:\temp\clipfiles=.

<pre>
<font color="#a020f0">Set</font> WshShell <font color="#804040"><b>=</b></font> WScript<font color="#804040"><b>.</b></font><font color="#008080">CreateObject</font><font color="#804040"><b>(</b></font><font color="#ff00ff">&quot;WScript.Shell&quot;</font><font color="#804040"><b>)</b></font>
WshShell<font color="#804040"><b>.</b></font>Run<font color="#804040"><b>(</b></font><font color="#ff00ff">&quot;clipbrd.exe&quot;</font><font color="#804040"><b>)</b></font>
WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">20000</font>

startFolder<font color="#804040"><b>=</b></font><font color="#ff00ff">&quot;c:\temp\clipfiles&quot;</font>
<font color="#a020f0">set</font> folder<font color="#804040"><b>=</b></font><font color="#008080">CreateObject</font><font color="#804040"><b>(</b></font><font color="#ff00ff">&quot;Scripting.FileSystemObject&quot;</font><font color="#804040"><b>).</b></font>GetFolder<font color="#804040"><b>(</b></font>startFolder<font color="#804040"><b>)</b></font>
<font color="#804040"><b>for</b></font> <font color="#804040"><b>each</b></font> file <font color="#804040"><b>in</b></font> folder<font color="#804040"><b>.</b></font><font color="#a020f0">files</font>
  WScript<font color="#804040"><b>.</b></font>Echo <font color="#ff00ff">&quot;Now testing &quot;</font> <font color="#804040"><b>&amp;</b></font> file<font color="#804040"><b>.</b></font>Path
  OpenClipFile<font color="#804040"><b>(</b></font>file<font color="#804040"><b>.</b></font>Path<font color="#804040"><b>)</b></font>
  <font color="#0000ff">' Add here:</font>
  <font color="#0000ff">' - Activate application under test</font>
  <font color="#0000ff">' - Have it paste data from the clipboard</font>
  <font color="#0000ff">' - Verify that the data comes in as expected</font>
<font color="#804040"><b>next</b></font>

<font color="#0000ff">' Close clipbrd.exe</font>
WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>AppActivate</b></font><font color="#804040"><b>(</b></font><font color="#ff00ff">&quot;ClipBook Viewer&quot;</font><font color="#804040"><b>)</b></font>
WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;%F&quot;</font>
WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">1000</font>
WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;x&quot;</font>

<font color="#804040"><b>Sub</b></font> OpenClipFile<font color="#804040"><b>(</b></font>filename<font color="#804040"><b>)</b></font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>AppActivate</b></font><font color="#804040"><b>(</b></font><font color="#ff00ff">&quot;ClipBook Viewer&quot;</font><font color="#804040"><b>)</b></font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;%W&quot;</font>  <font color="#0000ff">' ALT-W for Windows menu</font>
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">500</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;1&quot;</font>   <font color="#0000ff">' Activate Clipboard window</font>
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">500</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;%F&quot;</font>  <font color="#0000ff">' ALT-F for File menu</font>
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">1000</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;O&quot;</font>
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">1000</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> filenam9e
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">1000</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;{ENTER}&quot;</font>
  WScript<font color="#804040"><b>.</b></font>Sleep <font color="#ff00ff">1000</font>  <font color="#0000ff">' Wait for &quot;Clear clipboard (yes/no)?&quot;</font>
  WshShell<font color="#804040"><b>.</b></font><font color="#804040"><b>SendKeys</b></font> <font color="#ff00ff">&quot;{ENTER}&quot;</font>
<font color="#804040"><b>End</b></font> <font color="#804040"><b>Sub</b></font>

</pre>

I'm sure a <nop>VBscript hacker could tidy this up considerably and use it
to form a complete test suite. However, while this approach finally gives
us some degree of automation, it is still lacking in several ways:
   * The format for the =*.CLP= file is undocumented, so
     we cannot add clipboard data of our own, unless we first
     copy it to the clipboard, then save it from there using
     <nop>ClipBook Viewer.
   * Automation via sending keys is a very brittle approach.
     For instance, the above code was written for the English version
     of =clipbrd.exe=. The German or French or Lithuanian versions
     of =clipbrd.exe= might have completely different keyboard
     shortcuts.
   * I shudder when looking at those magic delay
     time values which the code is ridden with - what if we
     run on a really slow system? On a system which has even
     more networking problems than the one which I tested the
     code with?
   * Any process (or user) stealing the window focus while the test is running will break the test.

Hence, next time: Look Ma, no <tt>SendKeys</tt>!

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