Disclosure: a free e-copy of this book was received from the publisher for review purposes. The opinions expressed here are entirely my own; a copy of this review has also been posted at Amazon.
Greg L. Turnquist’s “Python Testing Cookbook” explores automated testing at all levels, with the intention of providing the reader with the knowledge needed to implement testing using Python tools to improve software quality. To this end the book presents over 70 “recipes” in its nine chapters (ranging from the basics of unit testing, through test suites, user acceptance and web application testing, continuous integration, and methods for smoke- and load-testing), covering both tools for testing Python, and Python tools for testing. It also delivers advice about how to get the most from automated testing, which is as much an art as a science.
The first three chapters introduce the fundamentals: writing, organising and running unit tests, comprehensively covering unittest (Python’s built-in unit testing library), nose (a versatile tool for discovering, running and reporting tests) and doctest (which turns Python docstrings into testable code – a sample of this chapter can be downloaded from http://www.packtpub.com/python-testing-cookbook/book). Having established a solid foundation, subsequent chapters look at increasingly broader levels of automated testing using the appropriate relevant Python tools: for example, the “lettuce” and “should_DSL” libraries for “behaviour driven development” (an extension of “test driven development” which aims to produce human-readable test cases and reports), and the “Pyccuracy” and “Robot” frameworks for end-user acceptance testing of web applications. Later chapters cover higher level concepts and tools, such as using nose to hook Python tests into “continuous integration” servers (both Jenkins and TeamCity are covered in detail), and assessing test coverage using the “coverage” tool (both as a metric, and to identify areas that need more tests). A detailed chapter on smoke- and load-testing includes practical advice on developing multiple test suites for different scenarios, and methods for stress-testing (for example, by capturing and replaying real world data) to discover weaknesses in a system before going to production. The final chapter distils the author’s experience into general advice on making testing a successful part of your code development methodology, both for new and legacy projects.
There’s a lot of good stuff in this book: the initial chapters on unittest and nose are particularly strong, and I can imagine returning to these in future as a reference. There is also a lot of excellent and hard-won practical advice from the author’s own experience – not only in these early chapters but throughout the book – which is consistently valuable (in this regard the final chapter is a real highlight and could easily stand alone – I will definitely be re-reading it soon). Elsewhere the various tools and topics are presented clearly with plenty of useful detail, and in some cases have demystified things that I’d always assumed were quite esoteric and difficult to do (nose in particular was a revelation to me, but also setting up continuous integration servers and measuring test coverage).
There are a few disappointments: the section on mock objects left me feeling baffled as to how to actually implement them in practice – a shame as it was something that I’d looked forward to learning. I’d also have liked something about approaches for handling difficult testing scenarios such as software which interacts with the file system or with large files – a few hints here would have been invaluable for me. There are typos in some commands and code in a few recipes (e.g. for nose), which meant I had to look up the correct syntax elsewhere – perhaps not so bad, but annoying (especially in a cookbook) – and since the recipes themselves aren’t numbered, this sometimes made it difficult to navigate between them.
However these are fairly minor quibbles, and in conclusion I was impressed with both the breadth of material covered by the book and the level of detail for many topics. Moreover I enjoyed reading it and was often left feeling excited at the prospect of being able to apply the ideas to my own projects, which is I think was one of the author’s aims (and no mean feat for a technical book). I think that the combination of the detail together with the author’s practical advice make this book both an excellent introduction to testing with Python, and a valuable resource to refer back to subsequently.
(Addendum: Greg Turnquist's blog about the book can be found at http://pythontestingcookbook.posterous.com/ and features some interesting supplementary material.)
Wednesday, July 27, 2011
Sunday, July 10, 2011
Fedora 15 and Gnome 3: user basics
I've been using Fedora 15 for about a month now and thought it was time to write up some of my experiences with the new Gnome 3 desktop, since certain aspects are quite a bit different from the previous version. I know other people have posted details about the Fedora 15 desktop (for example Xavier Claessens' One Week with Gnome 3) but when I first installed it there didn't seem to be much from a "user basics" perspective. So this is my take, hope it's useful.
Getting started
When you first start up Gnome 3 the desktop looks pretty empty - in fact there are no desktop icons in this new version (even when you put them in your "Desktop" subdirectory):
Figure 1: "Empty" Gnome 3 desktop on startup. No desktop icons allowed!
To get started, move the mouse to the word "Activities" at the top right-hand corner of the screen (the so-called "hot corner") - immediately changing the desktop to the "Windows" view:
Figure 2: "exploded view" of the Gnome 3 desktop, accessed either by moving the mouse over the "Activities" hot corner (top-left of the screen), or by hitting the "Gnome" (i.e. Windows) key on the keyboard. The Favourites sidebar sits on the left edge of the screen, and the edge of the Workspaces sidebar peeks out on the right.
In this view (figure 2) you can see the Favourites sidebar on the left side, and just the very edge of the Workspaces sidebar on the right (more about those below). I call this the exploded view of the current workspace, since (as in this example) features minatures of any windows in the workspace. The exploded view can also be toggled by pressing the"Gnome key" "Super key" (i.e. the Windows key).
From this view you can toggle to the "Applications" view, by clicking on "Applications" near the top left (figure 3):
Figure 3: "Applications" view of the Gnome 3 desktop
This shows all the applications installed on the system, with a search box and category groupings on the right to help you find the one you want.
The Favourites sidebar: launching and navigating applications
The Favourites sidebar is the strip down the left-hand side which holds various application icons. These icons do "double-duty": if you've dragged an icon there from elsewhere (essentially "favouriting" it), then it initially acts as a launcher for that application; also the icons for any running applications (favourited or otherwise) will appear here.
If an application already has one or more instances running then clicking on its icon takes you to the "nearest" running instance; clicking-and-holding (or right clicking) gives you more options (e.g. to start a new instance, or move to any of the currently open instances) - behaviour that is probably already familiar to users of Windows 7 and Mac OS X (figure 4):
Figure 4: The "Favourites" sidebar with dialogue (i.e. the black bubble) opened for Firefox after right-clicking on its icon. This gives options to move to a running Firefox window, or to start a new Firefox instance.
Another way to navigate between running applications is to use Alt+Tab to cycle between them (figure 5):
Figure 5: Alt+Tab moves between running applications...
Repeated Alt+Tabb'ing moves between the applications; if there's more than one instance running then these are also shown when you Alt+Tab to it, and you can use the arrow keys to navigate to the specific one you want (figure 6):
Figure 6: ... and arrow keys allow you to select a specific instance if there are multiple instances of a particular application.
The Workspaces sidebar: navigating multiple desktops
Workspaces provide a way to manage applications, by giving the user multiple virtual desktops. These should already be familiar to seasoned Gnome users, but they operate somewhat differently in Gnome 3: there are no longer a fixed number of workspaces, instead they are created and destroyed automatically by the system as required.
You can move between workspaces in at least two different ways. Firstly, you can access the workspaces sidebar on the right-hand side of the screen, by moving the mouse over it in the "exploded view" of the desktop and causing it to "pop out" (figure 7):
Figure 7: the Workspaces sidebar "popped out" on the right of the screen in the exploded view of the Gnome 3 desktop.
The sidebar shows miniatures of each workspace, with the current workspace highlighted with a white outline. Clicking on one of the images takes you to that workspace; you can also drag application windows between the different workspaces.
Note the sidebar also shows an extra "empty" workspace at the bottom: if an application is opened or moved into this workspace then a new empty workspace is automatically created underneath. Furthermore, there's only ever one empty workspace - so if a workspace "empties" (e.g. because you've closed all the applications it contains) then Gnome automatically removes it. This can be quite disconcerting, and is probably the feature that causes me the most confusion in practice as it often upsets my sense of where I am in the workspace order.
The other way to navigate between workspaces is Alt+Ctrl+Up/Down Arrows, which I find myself using quite a lot (although I frequently overshoot into the empty workspace by accident) (figure 8):
Figure 8: moving between multiple desktops using Alt+Ctrl+Up/Down keys
Other observations
Conclusion
Having been using Fedora 15 and Gnome 3 day-to-day for a few weeks now, I'm now largely used to its quirks and finding it overall a perfectly serviceable working environment - for me the new workspaces model and the rather random system notification mechanism have proved to be the most challenging differences from previous versions. So while it may not suit everyone's tastes it's definitely worth trying (and hopefully the more egregious foibles will be ironed out in future versions).
Getting started
When you first start up Gnome 3 the desktop looks pretty empty - in fact there are no desktop icons in this new version (even when you put them in your "Desktop" subdirectory):
Figure 1: "Empty" Gnome 3 desktop on startup. No desktop icons allowed!
To get started, move the mouse to the word "Activities" at the top right-hand corner of the screen (the so-called "hot corner") - immediately changing the desktop to the "Windows" view:
Figure 2: "exploded view" of the Gnome 3 desktop, accessed either by moving the mouse over the "Activities" hot corner (top-left of the screen), or by hitting the "Gnome" (i.e. Windows) key on the keyboard. The Favourites sidebar sits on the left edge of the screen, and the edge of the Workspaces sidebar peeks out on the right.
In this view (figure 2) you can see the Favourites sidebar on the left side, and just the very edge of the Workspaces sidebar on the right (more about those below). I call this the exploded view of the current workspace, since (as in this example) features minatures of any windows in the workspace. The exploded view can also be toggled by pressing the
From this view you can toggle to the "Applications" view, by clicking on "Applications" near the top left (figure 3):
Figure 3: "Applications" view of the Gnome 3 desktop
This shows all the applications installed on the system, with a search box and category groupings on the right to help you find the one you want.
- Drag icons from this view to the "Favourites" bar to make them more easily accessible in future.
- The "Add/remove software" application is a graphical front end to yum for installing and managing additional packages that are weren't included by default.
The Favourites sidebar: launching and navigating applications
The Favourites sidebar is the strip down the left-hand side which holds various application icons. These icons do "double-duty": if you've dragged an icon there from elsewhere (essentially "favouriting" it), then it initially acts as a launcher for that application; also the icons for any running applications (favourited or otherwise) will appear here.
If an application already has one or more instances running then clicking on its icon takes you to the "nearest" running instance; clicking-and-holding (or right clicking) gives you more options (e.g. to start a new instance, or move to any of the currently open instances) - behaviour that is probably already familiar to users of Windows 7 and Mac OS X (figure 4):
Figure 4: The "Favourites" sidebar with dialogue (i.e. the black bubble) opened for Firefox after right-clicking on its icon. This gives options to move to a running Firefox window, or to start a new Firefox instance.
Another way to navigate between running applications is to use Alt+Tab to cycle between them (figure 5):
Figure 5: Alt+Tab moves between running applications...
Repeated Alt+Tabb'ing moves between the applications; if there's more than one instance running then these are also shown when you Alt+Tab to it, and you can use the arrow keys to navigate to the specific one you want (figure 6):
Figure 6: ... and arrow keys allow you to select a specific instance if there are multiple instances of a particular application.
The Workspaces sidebar: navigating multiple desktops
Workspaces provide a way to manage applications, by giving the user multiple virtual desktops. These should already be familiar to seasoned Gnome users, but they operate somewhat differently in Gnome 3: there are no longer a fixed number of workspaces, instead they are created and destroyed automatically by the system as required.
You can move between workspaces in at least two different ways. Firstly, you can access the workspaces sidebar on the right-hand side of the screen, by moving the mouse over it in the "exploded view" of the desktop and causing it to "pop out" (figure 7):
Figure 7: the Workspaces sidebar "popped out" on the right of the screen in the exploded view of the Gnome 3 desktop.
The sidebar shows miniatures of each workspace, with the current workspace highlighted with a white outline. Clicking on one of the images takes you to that workspace; you can also drag application windows between the different workspaces.
Note the sidebar also shows an extra "empty" workspace at the bottom: if an application is opened or moved into this workspace then a new empty workspace is automatically created underneath. Furthermore, there's only ever one empty workspace - so if a workspace "empties" (e.g. because you've closed all the applications it contains) then Gnome automatically removes it. This can be quite disconcerting, and is probably the feature that causes me the most confusion in practice as it often upsets my sense of where I am in the workspace order.
The other way to navigate between workspaces is Alt+Ctrl+Up/Down Arrows, which I find myself using quite a lot (although I frequently overshoot into the empty workspace by accident) (figure 8):
Figure 8: moving between multiple desktops using Alt+Ctrl+Up/Down keys
Other observations
- Resizing windows: windows can be maximised by double-clicking on their title bar (double-click again to restore to the original size). There's no "minimise" button on the window frame, so you now have to right-click and then select the "Minimise" menu option. Also, note that dragging a window to the top of the screen automatically causes it to maximise (again similar to Windows 7, and not always what you intend). Manual resizing is also possible as always, by dragging the window edges - but this can be fiddly, as the area where an edge can be "caught" for dragging seems to be quite small.
- System notifications: these now pop up rather discreetly at the bottom of the screen, but interacting with then can be frustrating at times - often they disappear before you have a chance to read them, and sometimes (counterintuitvely) disappear when clicked.
- Customisation: while some preference-type options are available via the "username" menu (top right-hand corner of the screen) under "System Settings", overall the customisation options feel quite limited (for example, no screen-savers). However as a number of interfaces to system tools currently only seem to be accessible by launching from a command line, it's not clear if this a conscious design decision or whether more customisation options will be exposed in future versions.
- Fallback mode: this is a half-way house between Gnome 2 and Gnome 3, and is started by default on systems which can't support the full Gnome 3 experience (which appears to include virtual machines). However as it's much more like the old Gnome, if you really don't like the new version then you could try using fallback mode instead.
Conclusion
Having been using Fedora 15 and Gnome 3 day-to-day for a few weeks now, I'm now largely used to its quirks and finding it overall a perfectly serviceable working environment - for me the new workspaces model and the rather random system notification mechanism have proved to be the most challenging differences from previous versions. So while it may not suit everyone's tastes it's definitely worth trying (and hopefully the more egregious foibles will be ironed out in future versions).
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