On the 2cnd of July the PostgreSQL Global Development Group released an alpha version of the upcoming PostgreSQL 9.5. The same day, Josh Berkus, another of those PostgreSQL core team members released a docker image for testing this alpha release. It’s never been that easy to get started with PostgreSQL or testing new features.
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If you are on Linux the docker packages should be available for your distribution. For Oracle Linux 7.1 make sure that the addons yum repository is enabled

cat /etc/yum.repos.d/public-yum-ol7.repo | grep -A 3 addon
 name=Oracle Linux $releasever Add ons ($basearch)

Installing docker is just:

yum install -y docker
systemctl start docker.service

Once docker is running we can search the docker registry:

docker search postgres
NAME                    DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
postgres                The PostgreSQL object-relational database ...   809       [OK]       
abevoelker/postgres     Postgres 9.3 + WAL-E + PL/V8 and PL/Python...   7                    [OK]
linuxkonsult/postgres   A Postgres trusted build installed with Chef.   5                    [OK]
macadmins/postgres      Postgres that accepts remote connections b...   5                    [OK]
jamesbrink/postgres     Highly configurable PostgreSQL container.       2                    [OK]
kampka/postgres         A postgresql image build on top of an arch...   2                    [OK]
azukiapp/postgres       Docker image to run PostgreSQL by Azuki - ...   2                    [OK]
clkao/postgres-plv8     Docker image for running PLV8 1.4 on Postg...   1                    [OK]
eeacms/postgres         Docker image for PostgreSQL (RelStorage re...   0                    [OK]
bantl23/postgres        postgres development                            0                    [OK]

Get the PostgreSQL 9.5 alpha container and run it:

mkdir -p /var/tmp/docker/postgres
docker run -it --volume "/var/tmp/docker/postgres:/tests" jberkus/postgres95-test:alpha
Unable to find image 'jberkus/postgres95-test:alpha' locally
alpha: Pulling from jberkus/postgres95-test
39bb80489af7: Pull complete 
df2a0347c9d0: Pull complete 
65c152b01d5d: Pull complete 
22e16a33eefa: Pull complete 
b7003ab928a5: Pull complete 
b9ad663e6550: Pull complete 
712b208afbdf: Pull complete 
6db70337094f: Pull complete 
94dc52568254: Pull complete 
af3497b0915c: Pull complete 
203e588497fa: Pull complete 
35133c09fcd4: Already exists 
Digest: sha256:cd722ecdcfb68467d077f1edddf9cfcf1faabb954f544098a854bd8d83b61871
Status: Downloaded newer image for jberkus/postgres95-test:alpha

Looks good so we should be able to use it:

root@5e74f2e32422:/# su - postgres
postgres@5e74f2e32422:~$ pg_ctl start
server starting
postgres@5e74f2e32422:~$ [ @  @ 2015-07-03 06:57:09.840 GMT]:LOG:  redirecting log output to logging collector process
[ @  @ 2015-07-03 06:57:09.840 GMT]:HINT:  Future log output will appear in directory "pg_log".
postgres@5e74f2e32422:~$ psql
psql (9.5alpha1)
Type "help" for help.

postgres=# \l
                             List of databases
   Name    |  Owner   | Encoding | Collate | Ctype |   Access privileges   
 libdata   | libdata  | UTF8     | C       | C     | 
 postgres  | postgres | UTF8     | C       | C     | 
 template0 | postgres | UTF8     | C       | C     | =c/postgres          +
           |          |          |         |       | postgres=CTc/postgres
 template1 | postgres | UTF8     | C       | C     | =c/postgres          +
           |          |          |         |       | postgres=CTc/postgres
(4 rows)

Cool. Minimal effort to get a test infrastructure with docker. (Please notice that I did everything as root. It is always better to setup proper sudo permissions)