If you want to play or test various apps and settings you can use virtual machine instead of your mac. With VMware Fusion you can install virtual Mac OS X.

Apple’s End User license agreement allows you to install up to two additional copies of Mac OS X 10.9 on a Mac that is already running a retail version of the operating system and not a pre-installed version.

I this quick tutorial I will show you how ti install OS X Mavericks in VMware Fusion:

Download OS X Mavericks from App Store and VMware Fusion from official page

Step 1 Install VMware Fusion

Step 2 Select File > New from the Fusion menu bar.

Step 3 Select Install from disc or image and Click Continue.

Step 4 Drag and drop the Install OS X Mavericks application into Use operating system installation disc or image dialog box.

Step 5 Click Continue.

Step 6 Fusion should automatically discover the Guest Operating System. If not, ensure that the Operating System is set to Apple Mac OS X and that the version is set to Mac OS X 10.9. Click Continue.

Step 7 If you want to modify any of the settings, such as memory (RAM), CPU, or hard disk size, click Customize Settings and specify the non-default values.

Step 8 Click Finish. The installation starts.

Step 9 When prompted, select Reinstall Mac OS X and click Continue.

Step 10 Click Continue.

Step 11 Agree to the license agreement and follow the prompts to begin the installation.

Step 12 Enjoy

Update

If you have problems at step 8 (Unable to create the installation medium) follow this procedure:

Step 1 Quit VMware Fusion

Step 2 Download and unpack Create Mavericks Installer.zip.

Step 3 Open terminal and insert command (replace /users/ihash/download/ with your path). Enter your password if prompted.:

sudo cp /users/ihash/download/Create\ Mavericks\ Installer.tool /Applications/VMware\ Fusion.app/Contents/Library/

Step 4 Launch VMware Fusion, and try again.