Music Example With Errors



In this example we describe a music player as if we were operating it. This is an intentionally corrupted version of the MusicExample that shows how various errors are reported.

We'll write the remainder of this page as if it were describing stories for the music player. We'll use italics when we want to point out features of the framework. You might as well run the example now before you continue reading.


Browsing Music

The music browser starts up looking at the whole library of songs. We specify the library (an advanced feature) so that we know what we are talking about in this document.

fit.ActionFixture
start eg.music.Browser  
enter library Source/eg/music/Music.txt
check total songs 37

This is a the file that library reads. It is tab separated text. Try downloading it and looking at it with a spreadsheet. http:Release/Source/eg/music/Music.txt

We can pick songs and see details of our selection as we go.

fit.ActionFixture
enter select 1
check title Akila
check artist Toure Kunda
enter select 2
check title American Tango
check artist Weather Report
check album Mysterious Traveller
check year 1975
check time 3.70
check track 2 of 7

ActionFixture interprets the words in the first column. The check action leads to a comparison of expected values from the table with actual values from the music program.


Playing Music

Once we've picked a song, we can play it. We can continue operating the Brower while music is playing.

eg.music.Realtime
press play  
check status loading
pause 2  
check status playing
pause 2  
check status playing
check time 3.70
press pause  
check status pause
check remaining 3.66
pause 60  
check remaining 3.66
press play  
check status playing
pause 60  
check remaining 2.66
await play complete  
check status ready

The RealtimeActionFixture is a Fixture that adds actions having to do with realtime operation of the music player. We start by pressing play and then waiting for the status to show that it is playing. This music takes 2.5 seconds to start playing so it still says loading after our 2 second pause.

Warning: Don't confuse the pause action with the pause button. The pause action appears in column one where it is interpreted by the Simulator as if the user hesitates for a specified number of seconds. The pause button is a button on the music player part of the Browser screen. The press action activates the pause button which causes the currently playing song to stop temporarily.


Searching for Music

There are buttons on the browser to find more songs like the one we have picked.

We can find songs related in different ways. Each new way produces a (possibly) different list of songs. Show all restores the display to the initial conditions.

eg.music.Realtime
press show all  
check selected songs 37
enter select 3
check artist James Taylor
press same artist  
check selected songs 5

We left out the await actions so we are mashing buttons every second or so, faster than the searches complete. We're still getting the music we wanted because the search routines don't yet do a very good job of simulating being slow.

Yielding the display:

eg.music.Display
title artist album year time() track()
Handy Man James Taylor JT 1977 3.30 7 of 12
Scarlet Woman Weather Report Mysterious Traveller 1974 5.72 6 of 7
Sailing To Philadelphia James Taylor October Rose 2000 5.47 3 of 3
Ananas James Taylor Hourglass 1997 5.73 5 of 13
Another Gray Morning James Taylor JT 1977 2.73 4 of 12

The song Scarlet Woman is marked as missing because our search did not return this row. It really is missing, and rightfully so, because it isn't a James Taylor song.

The song Another Gray Morning is marked as missing because there is no song spelt that way in the result set. When left hand columns (the keys) disagree then we don't get a chance to compare the remaining columns.

The song Copperline wasn't expected in the result set so it is marked as surplus. The framework adds all the surplus songs to the table so that they can be seen. The show up with printing in light gray as a reminder that they are not a part of the original document.

This completes the MusicExample.


Now we consider some degenerate cases just to be sure that they work. Suppose we did not uniquely identify rows. We have two songs from JT. What happens when there are surplus (only one expected) ? When there are missing (three expelcted)?

eg.music.Display
album genre
October Rose Pop
Hourglass Pop
New Moon Shine Pop
JT Pop

eg.music.Display
album genre
JT Pop
October Rose Pop
JT Pop
Hourglass Pop
JT Pop
New Moon Shine Pop


We've run quite a few test. We'll call up one more Fixture that will add a summary to the end of our document.

fit.Summary

 

Last edited October 10, 2002
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