Music Example



In this example we describe a music player as if we were operating it. We will see two kinds of tables in use, action and row. The action tables list things actions to be performed, step-by-step, one row at a time. Some actions will involve searching for music. We will check to be sure we've found the right music using a second kind of table, a row table. In the row table we will simply list each song, one per row, with columns showing different attributes of each song. We'll use these fixtures.

  • ActionFixture -- Calls up player screens and pushes their buttons.
  • Browser (a plain Fixture) -- The first (only) screen of the player.
  • Display ( a RowFixture) -- Search results to be displayed by the screen.
  • Simulator (an ActionFixture) -- A variation that simulates realtime actions.

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 1974
check time 3.70
check track 2 of 7

ActionFixture interprets the words in the first column. The actions operate on fields and buttons on the Browser screen we started in the first table. The Browser (or what ever other Fixtures we start) interprets the names in the second column. Each name maps to a method of the Browser. The third column provides data that are pass as arguments to Browser methods or compared with Browser method results. See MusicExampleWithErrors to see how errors are reported.


Playing Music

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

eg.music.Simulator
press play  
check status loading
pause 2  
check status loading
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 Simulator is a Fixture that adds actions having to do with realtime operation of the music player. We call it a simulator because the application we are testing isn't a real music player. Our toy application cooperates with the simulator to keep track of time. A real player would do things that take real time and it would use the computer's realtime clock to keep track of time. We could still use a fixture with actions like pause and await but it wouldn't need to be a simulator too.


Searching for Music

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

eg.music.Simulator
press same album  
check status searching
await search complete  
check status ready
check selected songs 2

Our searches take a few seconds to complete. Eventually we will want to try mashing buttons faster than the computer can respond. For now we will be polite and await completion of our searches.

The selected songs are displayed in a table.

eg.music.Display
title artist album year time() track()
Scarlet Woman Weather Report Mysterious Traveller 1974 5.72 6 of 7
American Tango Weather Report Mysterious Traveller 1974 3.70 2 of 7

Here we use Display (a RowFixture) to directly examine the Music object found by our search. Things like artist and track() are fields and methods of the domain objects.

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.Simulator
press show all  
await search complete  
check selected songs 37
enter select 3
check artist James Taylor
press same artist  
await search complete  
check selected songs 5

Yielding the display:

eg.music.Display
title artist album year time() track()
Handy Man James Taylor JT 1977 3.30 7 of 12
Sailing To Philadelphia James Taylor October Rose 2001 5.47 3 of 3
Ananas James Taylor Hourglass 1997 5.73 5 of 13
Another Grey Morning James Taylor JT 1977 2.73 4 of 12
Copperline James Taylor New Moon Shine 1991 4.37 1 of 12

Domain objects typically have lots more fields and methods than we can conveniently look at in a single table. We compose a table specific to our needs by choosing column headings of interest. Here is another look at the results of the previous search.

eg.music.Display
title album genre size date
Another Grey Morning JT Pop 3284199 9/7/02 11:32 PM
Ananas Hourglass Pop 6897450 9/7/02 11:47 PM
Copperline New Moon Shine Pop 5248087 9/7/02 9:52 PM
Handy Man JT Pop 3976956 9/7/02 11:36 PM
Sailing To Philadelphia October Rose Pop 6581911 9/7/02 10:45 PM

Notice that the songs in the two tables are not in the same order. That is because we didn't type the tables in the same order, and the order we type is preserved. RowFixture(s) use the left hand columns to line up the search results with the table values. Check out MusicExampleWithErrors to see how this works when the rows don't match up.

This completes the MusicExample.


See the fixtures.

See the application.


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 6, 2002
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