Distributed Coding Prefunc: Ubuntu Erlang Dev & EUnit

Erlang LogoAfter installing Erlang on OS-X and then getting QuickCheck installing via Erlang, I wanted to expand the OS options I’m using to Ubuntu (i.e. Linux). So in this entry I’m going to cover the Erlang install, a quick eunit bit, and then a QuickCheck install and sample. The first step in geting Erlang installed is deciding how you want to install it. So far, it isn’t like Rails where it is pretty important which method you pick to how well it will work for you on Ubuntu. For Erlang all methods get you started with a good version that is working. The method I used was simply to install with apt-get.

[sourcecode language=”bash”]
sudo apt-get install erlang erlang-doc
[/sourcecode]

After installing, always a good idea to run things and make sure they’re all content and happy with your machine. Startup the erlang shell.

[sourcecode language=”bash”]
erl
[/sourcecode]

Then run some of the commands. Some I’ve found that will present you with useful and interesting information ist he erlang:system_info function with appropriate parameter passed. The otp_release parameter will get the version of erlang, the cpu_topology shows you the processor outlay for you machine (or in this case my virtual machine, with a single processor core allocated to it), and allocated_areas shows a bit about system memory allocations.

[sourcecode language=”erlang”]
Eshell V5.9.1 (abort with ^G)
1> erlang:system_info(otp_release).
"R15B01"
2> erlang:system_info(cpu_topology).
[{processor,{logical,0}}]
3> erlang:system_info(allocated_areas).
[{sys_misc,80748},
{static,1007616},
{atom_space,98328,73387},
{atom_table,95961},
{module_table,9084},
{export_table,50316},
{export_list,240960},
{register_table,180},
{fun_table,3266},
{module_refs,2048},
{loaded_code,3437028},
{dist_table,403},
{node_table,227},
{bits_bufs_size,0},
{bif_timer,80200},
{link_lh,0},
{process_table,262144},
{ets_misc,52504}]
[{processor,{logical,0}}]
[/sourcecode]

Now that erlang is effectively installed we can write a little sample code. To do this I created a directory called “TestingErlang” and in it placed an Erlang code file called “eunit_tests.erl”. Note: I’m using Sublime 2 on Ubuntu, so exchange that for whatever text editor you’re using for your Erlang coding.

[sourcecode language=”bash”]
adron@ubuntu:~/Codez$ mkdir TestingErlang
adron@ubuntu:~/Codez$ cd TestingErlang
adron@ubuntu:~/Codez/TestingErlang$ sublime eunit_tests.erl
[/sourcecode]

Add the header file include.

[sourcecode language=”erlang”]
-define(NOTEST, true).
-include_lib("eunit/include/eunit.hrl").
[/sourcecode]

Adding the header file include will cause all the function with _test() or _test_() to automatically be exported. An exported function of test() is created that can be used for running all of the unit tests. This also will include the preprocessor macros of EUnit for writing tests. So now throw a super simple test into the file.

You may want to, amid the automatic export of the methods ending in _test() or _test_() not name them this, and you’ll then need to add a line at the top of your code file like this.

[sourcecode language=”erlang”]
-export([reverse_test/0]).
[/sourcecode]

After this, add the function test as shown below.

[sourcecode language=”erlang”]
reverse_test() -> lists:reverse([1,2,3]).
[/sourcecode]

The complete code file should look like this.

[sourcecode language=”erlang”]
-module(eunit_test).
-define(NOTEST, true).
-include_lib("eunit/include/eunit.hrl").
-export([reverse_test/0]).

reverse_test() -> lists:reverse([1,2,3]).
[/sourcecode]

Build it and call the function.

[sourcecode language=”bash”]
Eshell V5.9.1 (abort with ^G)
1> c(eunit_test).
{ok,eunit_test}
2> eunit_test:reverse_test().
[3,2,1]
3>
[/sourcecode]

BOOM! Passing. So now we know we have a good Erlang install and eunit is setup and usable. In the following blog entries I have in the works, we’ll dive deeper into what and how Erlang works from an extremely basic level all the way to diving into some of the more complex features.

Distributed Coding Prefunc: Installing QuickCheck for Great Testing

Erlang LogoA few weeks ago I kicked off this series of “Distributed Coding Prefunc: Up and Running with Erlang” and had wanted to keep up the momentum, but as life goes I had to tackle a few other things first. But now, it’s time to get back on track with some distributed computing. I intend to write tests with my samples, as I often do, I decided to take a stab at .

Before going forward, note that there is QuickCheck for Haskell and there is a QuickCheck for Erlang. Since the point of this “Distributed Coding Prefunc” is to get started coding with Erlang from zero, I’ll be talking about the Erlang version here. This version is created by John Hughes and Koen Claessen, starting the Quviq Company in 2006.

To download QuickCheck choose the version you intend to use, I’ve chosen the commercial license version from the download page.

At the command prompt, install QuickCheck by running Erlang and then run the install with these commands.

Launch Erlang:

[sourcecode language=”bash”]
$ erl
Erlang R15B01 (erts-5.9.1) [source] [smp:4:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.9.1 (abort with ^G)
1>
[/sourcecode]

Then execute the install:

[sourcecode language=”Erlang”]
1> eqc_install:install().
[/sourcecode]

If the execution of the install displays this error, you’ll need to use sudo.

[sourcecode language=”bash”]
Installing ["pulse-1.27.7","eqc-1.27.7","eqc_mcerlang-1.27.7"].
Failed to copy pulse-1.27.7–copy returned {error,eacces}??
** exception exit: {{error,eacces},"pulse-1.27.7"}
in function eqc_install:’-copy_quickcheck/3-lc$^0/1-0-‘/3 (../src/eqc_install.erl, line 63)
in call from eqc_install:install2/4 (../src/eqc_install.erl, line 44)
[/sourcecode]

Kill Erlang with a ctrl+c and restart Erlang with the sudo command.

[sourcecode language=”bash”]
$ sudo erl
[/sourcecode]

Now when you install you should see the following result or something similar. You’ll be asked to continue, select lowercase ‘y’ to continue. It may be different for some, but when I hit uppercase ‘Y’ (I suppose I got overzealous to install QuickCheck) it finished as if I’d hit no or something else.

[sourcecode language=”bash”]
1> eqc_install:install().
Installation program for "Quviq QuickCheck" version 1.27.7.
Installing in directory /usr/local/lib/erlang/lib.
This will delete conflicting versions of QuickCheck, namely
[]
Proceed? y
Installing ["pulse-1.27.7","eqc-1.27.7","eqc_mcerlang-1.27.7"].
Quviq QuickCheck is installed successfully.
Looking in "/Users/adronhall"… .emacs not found
Could not find your .emacs file!
Try install("path-to-emacs-file") or install(new_emacs).
Bookmark the documentation at /usr/local/lib/erlang/lib/eqc-1.27.7/doc/index.html.
ok
[/sourcecode]

You’ll note above, I don’t currently have emacs installed. The reason it looks for emacs is because QuickCheck has templates/ops mode for emacs. So if you use emacs you’re in luck. I on the other hand, don’t, so I’ll just be using this from wherever I’m using it.

In addition to the lack of emacs, another important thing to note from the message is the link to documentation. Once you get this link open it up and check out the docs. They’re broken out into easily readily topic spaces and are a good place to do initial reference checking while you’re writing up your specs.

If you have a license, it is important to note, that if you’ve used sudo with your installation you’ll need to kill your running Erlang session and start it anew without sudo. Otherwise you’ll run into issue down the road trying to use the libs (unless of course you want to go hack on your permissions manually). Once you’re ready to register the software it’s simply one command, where xxxxx is your license key.

[sourcecode language=”bash”]
eqc:registration("xxxxxxxxxxxx").
[/sourcecode]

Alright, next time we’re on to next steps…